Sleep and Daily Rhythms

Activities Guide for Teachers

National Space Biomedical Research Institute Houston, Texas The National Space Biomedical Research Institute (NSBRI) is combining the basic research capabilities of some of the nation’s leading biomedical research centers with operational and applied research conducted by the National Aeronautics and Space Administration (NASA) to understand and achieve safe and effective long-term human exploration and development of space. The NSBRI’s discoveries and research products will help to counter the effects of weightlessness and space radiation and will contribute to the health and well-being of all mankind.

National Space Biomedical Research Institute One Baylor Plaza, NA-425 Houston, Texas 77030-3498 http://www.nsbri.org

The activities described in this book are intended for school-age children under direct supervision of adults. The authors, Baylor College of Medicine and the National Space Biomedical Research Institute cannot be responsible for any accidents or injuries that may result from conduct of the activities, from not specifically following directions, or from ignoring cautions contained in the text. The opinions, findings and conclusions expressed in this publication are solely those of the authors and do not necessarily reflect the views of Baylor College of Medicine or the National Space Biomedical Research Institute.

Authors: Nancy P. Moreno, Ph.D. and Barbara Z. Tharp, M.S. Cover Illustration: T Lewis Design and Production: Martha S. Young Acknowledgments The authors gratefully acknowledge the support of Bobby R. Alford, M.D.; Laurence R. Young, Sc.D.; and Ronald J. White, Ph.D.; as well as the contributions of the following science reviewers: Mary A. Carskadon, Ph.D.; Kimberly Chang, Ph.D.; Charles A. Czeisler, Ph.D., M.D.; David F. Dinges, Ph.D.; Hans P.A. Van Dongen, Ph.D.; and Kenneth P. Wright, Jr., Ph.D. Preparation of this guide would not have been possible without the invaluable assistance of the following field test teachers: Yolanda Adams, Jeri Alloway, Vivian Ashley, Susan Babac, Henrietta Barrera, Paula Clark, Carol Daniels, Barbara Foreman, Carolyn Hopper, Susan King-Martin, Mary Helen Kirby, Sue Klein, Jacqueline McMahon, Sandra Prill, Carol Reams, Mary Ellen Reid, Saundra Saunders, Angi Signorelli, and Marcia Wutke.

The National Aeronautics and Space Administration (NASA) supported this work through the NASA Cooperative Agreement NCC9-58 with the National Space Biomedical Research Institute.

All rights reserved. No part of this book may be reproduced by any mechanical, photographic or electronic process, or in the form of an audio recording; nor may it be stored in a retrieval system, transmitted, or otherwise copied for public or private use without prior written permission of the publisher. Black-line masters reproduced for classroom use are excepted.

What Can We Learn in Space About Our bodies Here on Earth? iv

Using Cooperative Groups in the Classroom vi

1. What Goes Around ... 1 2. Living Clocks 6 3. Sleepy Time 11 4. I’ve Got Rhythm 14 5. Shifting Shadows 17 6. Sleeping in Space 20 7. Twenty-Four Hours a Day 24

From Outerspace to Innerspace / Sleep and Daily Rhythms © 2000 Baylor College of Medicine iii here are many reasons to study life sciences in microgravity, from obvious ones such as ensuring T astronaut health to less obvious ones such as improving health care on Earth. The human body is designed to operate in Earth’s gravity field. When humans are removed from this environment, as when they travel in space, many complex changes take place: their bones become weaker, fluids shift toward the upper body, body rhythms are disrupted and motion sickness may occur. Life science research allows us to begin planning for long-term stays in space and provides important new medical information that may affect the health care of people here on Earth, such as the ways we care for persons undergoing prolonged bedrest, or those with osteoporosis.

BALANCE. During their first days in space, astronauts can become dizzy and nauseated. Eventually they get over it, but once they return to Earth, they have a hard time walking and standing upright. Finding ways to counteract these changes could benefit millions of Americans with balance disorders.

BONES. Astronauts’ bones become weak and porous, because the bones are not working against the Earth’s gravity. Many people on Earth, particularly older women, also develop weak bones. Space research on bone will help millions of people with osteoporosis.

CANCER/RADIATION. Outside the Earth’s protective atmosphere, astronauts are exposed to many kinds of damaging radiation that can lead to cell damage and increase astronauts’ chances of developing tumors. Learning how to keep astronauts safe from space radiation may improve cancer treatments for people on Earth.

From Outerspace to Innerspace / Sleep and Daily Rhythms iv © 2000 Baylor College of Medicine HEART & CIRCULATION. Without gravity, the amount of blood in the body is reduced. The heart becomes smaller and weaker. This becomes a problem when astronauts return to Earth. It makes them feel dizzy and weak. Heart failure and diabetes, experienced by many people on Earth, lead to similar problems.

IMMUNE SYSTEM. It may be easier for astronauts to become sick or develop diseases by living and working in space. Learning about changes in the astronauts’ blood and immune systems will help us understand many diseases already here on Earth.

MUSCLES. When muscles do not have to work against gravity, they weaken and begin to waste away. Special exercises and other strategies to help astronauts’ muscles stay strong in space also may help older and bedridden people, who experience similar problems on Earth.

SLEEP & WORK. It is hard for astronauts to get enough sleep because the day/night cycle of Earth is lost and there are many distractions. Strategies to help astronauts perform without errors also will benefit people such as airline pilots, or those who must work at night.

TECHNOLOGY. Special systems and equipment, new diagnostic tools and intelligent computer software that support life science research—as well as the health of astronauts in space—also will improve diagnosis and care for patients on Earth.

Cooperative learning is a systematic way for The Teaming Up! model* provides an efficient system students to work together in groups of two to four. It for cooperative learning. Four “jobs” are delineated: provides an organized setting for group interaction Principal Investigator, Materials Manager, Reporter and enables students to share ideas and to learn and Maintenance Director. Each job entails specific from one another. Students in such an environment responsibilities. Students wear job badges that are more likely to take responsibility for their own describe their duties. Tasks are rotated within each learning. Cooperative groups provide support for group for different activities so that each student has reluctant learners, an opportunity to model community experience all roles. settings where Teachers even may want cooperation is to make class charts to necessary, and enable coordinate the teacher to conduct job assignments within hands-on investigations groups. For groups with fewer materials. with fewer than four students, job Organization is essential assignments can be for cooperative learning combined. to occur in a hands-on science classroom. Once a cooperative model Materials must be managed, investigations for learning is established in the classroom, students conducted, results recorded, and clean-up directed are able to conduct science activities in an organized and carried out. When a class is “doing” science, and effective manner. All students are aware of their each student must have a specific role, or chaos responsibilities and are able to contribute to may result. successful group efforts.

Principal Investigator Maintenance Director Reporter Materials Manager

● Reads the directions ● Follows the safety rules ● Writes down observa- ● Picks up the materials tions and results ● Asks the questions ● Directs the clean up ● Uses the equipment ● Explains the results ● Checks the work ● Asks others to help ● Returns the materials ● Tells the teacher when the group is finished

* Jones, R.M. 1990. Teaming Up! LaPorte, Texas: ITGROUP. Extension Activities

There are many opportunities for exciting extension provide a wealth of educational resources that may be activities focusing on space travel and its effects on the useful in developing such activities. For more infor- human body. The NASA and NSBRI internet sites mation, go to and .

From Outerspace to Innerspace / Sleep and Daily Rhythms vi © 2000 Baylor College of Medicine CONCEPTS ● The Earth rotates completely on its axis about every 24 hours. ● Cycles of day and night are caused by this rotation and the Earth’s position relative to the sun. OVERVIEW Students will make a “mini-globe” to discover what makes day and night happen on Earth. SCIENCE,, HEHEALTH & MATH SKILLS ● Observing ● Measuring ● Modeling ● Mapping ● Drawing conclusions 1. What Goes Around . . . Background Time Our lives and those of other organisms on 20 minutes for set-up; 30 minutes to Earth are shaped in countless ways by conduct activity the cycles of day and night. This repeating pattern of light and darkness is caused Materials by the spinning of our planet and the Each group will need: position of the sun. ● large paper clip The Earth rotates ● table tennis (ping-pong) or round foam at a speed of about Earth, like other planets in our solar ball (diameter of 1–2 in.) 1,600 kilometers per ● system, revolves around the sun in a flashlight hour. Each day on slightly elliptical orbit. As it does so, the ● sheet of cardstock (8 1/2 x 11 in.) Earth lasts about 24 Earth also rotates, or spins, on its axis. ● pencils or permanent colored markers It takes about 24 hours for Earth to ● copy of “Spinning Worlds” student sheet hours, when measured complete one rotation. As students will ● copy of “Day & Night” student sheet according to the discover through the activities in this position of the sun in unit, functions of living organisms are Setup and Management the sky. Day lengths are linked to this cycle. Before the activity, follow the student different on other instructions on page 4 and make a planets. One rotation During one 24-hour period, a given demonstration “mini-globe,” using a location on Earth will experience several ball, paper clip, sheet of card stock of Mars takes 24.6 hours of sunlight (day time) followed by a and markers. Earth hours; one period of darkness (night time). One rotation of Jupiter is complete rotation equals one day. If using table tennis balls, make a small 9.9 Earth hours; and hole in the bottom of each ball using a one rotation of Venus As viewed from the North Pole, the Earth push pin before distributing the balls to takes 243 Earth days! spins counterclockwise. This makes the students. For younger students, you also sun appear to come up in the east and to may want to straighten the paper clip set in the west. In reality, of course, the as directed. position of the sun remains relatively constant—while the Earth rotates. The Place the materials for each session in following activity helps students visualize a central area for Materials Managers to this process through the creation of a collect for their groups. Have students simple model. The model will help work in groups. students understand the Earth’s rotation about its axis and the occurrence of day Procedure and night. It also will demonstrate the 1. Challenge students to think about slight tilt in the axis of the Earth. what causes night and day to happen

From Outerspace to Innerspace / Sleep and Daily Rhythms 1 © 2000 Baylor College of Medicine The length of day and night changes throughout the year as a result of the Earth’s tilted axis. The axis is Students will create models of the Earth to understand its rotation. the imaginary line that runs from the on Earth. Conduct a discussion and the grade level. Tell students that North Pole through list students’ ideas on the board. they will be using similar materials Challenge their thinking by posing to make their models. Distribute the the center of the Earth questions such as, Are days and Spinning Worlds directions sheets to to the South Pole. If nights always the same length? Is day students and instruct the Materials the axis were straight always followed by night? Does the Managers to pick up supplies for their up and down relative sun shine at night? Why does the sun groups from a central area. to the sun, all days appear in the east in the morning and and nights would be disappear in the west in the evening? 4. Have students build their models 12 hours long If you add the number of hours in a following the instructions given on day to the number of hours in the the “Spinning Worlds” sheet. throughout the year. following night, will the sum always However, since the equal 24 hours? List any additional 5. Once they have completed their axis is slightly tilted, questions that are posed by students. models, have students identify which the hemisphere that end of the model Earth represents leans toward the sun 2. Tell students that they will be the North Pole. Next, have them at any given time conducting an investigation to help determine in which direction the answer many of their questions about model Earth must spin if it is to experiences longer day and night on Earth. Explain that rotate in a counterclockwise direction days and shorter each group will construct a small when viewed from above the North nights. That model of the Earth and investigate Pole. You may need to review hemisphere also what happens when light shines on clockwise and counterclockwise for receives more direct the model. students. Have students stand and rays of light. face the same direction. Have them The combined effect 3. Show the students a mini-globe you turn in place, first clockwise, have made using a small ball, large then counterclockwise. of longer days and paper clip, more direct light

Activity 1 sheet of card 6. Distribute Activity 1 causes the season stock and copies of You will need: Name: known as summer. Table tennis (ping-pong) or foam ball Large paper clip You will need: Sheet of heavy paper or cardstock Colored markers markers (see the “Day & Earth model that you constructed Flashlight Make a model of the Earth by following these steps. You will use a flashlight to demonstrate how the sun shines toward Earth. 1. Fold the heavy paper in half twice. This will make four equal sections. 1. Hold the flashlight so that it points toward your Earth model Smooth the sheet and label the folds as shown to the right.. along the marking for 12:00 noon. 2. Draw a line around the widest part of the ball using a pencil or marker. This 2. Color a small dot on the Earth model that represents where directions on Night” page to you live. You will be observing what happens to this dot as the represents the equator on your Earth model. Earth model rotates. 3. Draw the continents on the ball using the diagrams below as guides. Be sure to notice which pole is north and which is south. 3. Rotate the Earth model counterclockwise until the dot is at 6:00 a.m. This represents early morning in your locality. Notice where the sun (flashlight) is. page 4). The each group Is the dot in the light or in the dark? Does the light shine directly toward the dot or to one side? 4. Rotate the Earth model 90 degrees (1/4 of a circle) in a counterclockwise direction. Notice where the sun (flashlight) is. equator model can be and have Is the dot in the light or in the dark? Does the light shine directly toward the dot or to one side? 5. Rotate the Earth model another 90 degrees (1/4 of a circle). Notice where the sun (flashlight) is. Is the dot in the light or in the dark? View of North and South America View of Eurasia and Africa as simple or as them work Does the light shine directly toward the dot or to one side? 4. Straighten one of the loops of the paper clip. Tape the unbent half onto the center point of 6. Rotate the Earth model another 90 degrees (1/4 of a circle). Notice where the sun (flashlight) is. the folds of the paper. Is the dot in the light or in the dark? 5. Push the globe over the straight Does the light shine directly toward the dot or to one side? part of the paper clip, with elaborate as through the 7. Based on your observations, write a short paragraph below describing why the sun appears overhead the North Pole almost facing upward. Your model should at noon, is visible in the western part of the sky in the evening and cannot be seen at midnight. look like the drawing to the right. you choose, questions

4 National Space Biomedical Research Institute From Outerspace to Innerspace / Sleep and Daily Rhythms From Outerspace to Innerspace / Sleep and Daily Rhythms National Space Biomedical Research Institute 5 http://www.nsbri.org © 2000 Baylor College of Medicine depending on provided. © 2000 Baylor College of Medicine http://www.nsbri.org

2 From Outerspace to Innerspace / Sleep and Daily Rhythms © 2000 Baylor College of Medicine 7. Depending on the ages of your Extensions students, you also may want to ● Using information available in the discuss the effect of the Earth’s tilted newspaper, from weather broadcasts Rotation (turning axis on day length throughout the or on the Internet, have students keep a year, and on the seasons, as record of the times of sunrise and sunset around a center described on page two. for several weeks for their locality. If pos- point or axis) is sible, compare the information to times measured in degrees. 8. Ask students to reconsider each of for a location in A complete rotation is the questions that were asked at the Southern Hemisphere. 360°. As seen from the the beginning of the activity. Have ● Astronauts in orbit circle the Earth North Pole, the Earth students use their models to provide every 90 minutes. Have students calcu- the answers. Are days and nights late the number of day/night cycles that rotates in a always the same length? No, for each a crew of astronauts might experience counterclockwise location, day and night lengths vary during a 24-hour period aboard the direction—or from according to the time of year and space shuttle. west to east. distance from the equator. Is day ● Challenge students to think about always followed by night? Yes, in why portions of the Arctic are referred to most locations. However, the sun is as the “Land of the Midnight Sun.” Help The common visible all the time at the poles during them understand that, during summer in the summer season. Does the sun the Northern Hemisphere, the North Pole abbreviation for shine at night? Yes, the sun always is and Arctic regions face toward the sun. morning, a.m., comes shining, even though part of the This leads to continuous light throughout from the Latin ante planet is in darkness. Similarly, part the day and night periods. Have students meridiem, which of Earth always is facing away and think about what happens when the means “before noon.” shaded from the sun. Why does the South Pole and Antarctic regions are tilt- The abbreviation, sun appear in the east in the morning ed toward the sun, and what happens to and disappear in the west in the these regions during winter months. p.m., comes from the evening? The direction of rotation of ● Discuss with students the effect of Latin post meridiem, the planet makes the sun appear to the Earth’s tilt on the seasons. For exam- meaning “after noon.” rise in the east and ple, when it is winter in the Northern to set in the west. If you add the Hemisphere, it is summer in the number of hours in a day to the Southern Hemisphere. Give students a number of hours in the following night, list of various cities around the world. will the sum always equal 24 hours? Have them predict whether residents of For all locations, except the each city would be experiencing winter geographic north and south poles, or summer in July. Next, have students each day/night cycle equals about use a globe to locate each city and verify 24 hours. their predictions.

You will need: Table tennis (ping-pong) or foam ball Large paper clip Sheet of heavy paper or cardstock Colored markers

Make a model of the Earth by following these steps. 1. Fold the heavy paper in half twice. This will make four equal sections. Smooth the sheet and label the folds as shown to the right.. 2. Draw a line around the widest part of the ball using a pencil or marker. This represents the equator on your Earth model. 3. Draw the continents on the ball using the diagrams below as guides. Be sure to notice which pole is north and which is south.

equator

View of North and South America View of Eurasia and Africa

4. Straighten one of the loops of the paper clip. Tape the unbent half onto the center point of the folds of the paper. 5. Push the globe over the straight part of the paper clip, with the North Pole almost facing upward. Your model should look like the drawing to the right.

Name: You will need: Earth model that you constructed Flashlight You will use a flashlight to demonstrate how the sun shines toward Earth. 1. Hold the flashlight so that it points toward your Earth model along the marking for 12:00 noon. 2. Color a small dot on the Earth model that represents where you live. You will be observing what happens to this dot as the Earth model rotates. 3. Rotate the Earth model counterclockwise until the dot is at 6:00 a.m. This represents early morning in your locality. Notice where the sun (flashlight) is. Is the dot in the light or in the dark? Does the light shine directly toward the dot or to one side? 4. Rotate the Earth model 90 degrees (1/4 of a circle) in a counterclockwise direction. Notice where the sun (flashlight) is. Is the dot in the light or in the dark? Does the light shine directly toward the dot or to one side? 5. Rotate the Earth model another 90 degrees (1/4 of a circle). Notice where the sun (flashlight) is. Is the dot in the light or in the dark? Does the light shine directly toward the dot or to one side? 6. Rotate the Earth model another 90 degrees (1/4 of a circle). Notice where the sun (flashlight) is. Is the dot in the light or in the dark? Does the light shine directly toward the dot or to one side? 7. Based on your observations, write a short paragraph below describing why the sun appears overhead at noon, is visible in the western part of the sky in the evening and cannot be seen at midnight.

From Outerspace to Innerspace / Sleep and Daily Rhythms National Space Biomedical Research Institute 5 © 2000 Baylor College of Medicine http://www.nsbri.org CONCEPTS ● Many activities of living things occur in cycles of about 24 hours. ● Daily cycles are governed by internal “clocks.” ● Internal clocks are cued by the environment, but run independently. OVERVIEW Students will observe that some behaviors and functions of living organisms vary predictably every 24 hours. SCIENCE,, HEHEALTH & MATH SKILLS ● Measuring ● Observing ● Drawing conclusions

2. Living Clocks Background Time Most living things behave predictably in Several 30-minute sessions, depending cycles of about 24 hours, similar to the on the options selected period of the Earth’s rotation. These cycles In 1729, the French are referred to as circadian, from the Latin Materials scientist Jean-Jacques words for “about” (circa) and “day” (dies). Materials will vary, depending on options selected. de Mairan was the There are many easily recognized ● source of natural sunlight first to notice that behavioral rhythms in nature. Well-known ● four bean plants per group (purchase the daily movements examples include the flowering of morning or grow in small pots from seed) of the leaves of certain glories at dawn and the hunting routines of ● fluorescent light (portable shop light plants continued owls at night. These behaviors are governed or plant “grow light”) even when the plants by internal mechanisms, often referred to ● one digital thermometer with several as “biological clocks,” within the cells of the sterile covers per group were kept in constant living organisms. When a biological clock ● study animals (gerbil, bird, crickets, etc.) dim light. Plants also runs on a 24-hour cycle, it also can be have many other called a circadian clock. Setup and Management activities that vary Students should work in cooperative according to the time Virtually all human body functions are groups (2–4 students). Conduct discus- of day. These activities governed by circadian clocks, such as sions with the entire class. include the opening waking and sleeping, body temperature (lower in the morning just after waking, Procedure of flowers, the release higher in the afternoon), secretion of some 1. Have students work in collaborative of fragrances, the hormones, and urine production. These groups to examine one or more of the opening and closing changes occur regularly over intervals of 24 following examples of daily cycles. of pores in the leaves hours—without cues from the environment. and the regulation of Researchers once thought that, without Body flowering at certain cues from the environment, the human temperature. Activity 2

Record the body temperature (temp.) in °F of each member of your group three times each day. times of the year circadian clock eventually would drift into Have students For best results, take the first reading just after waking in the morning and the third reading just before going to sleep at night. Wait at least 15 minutes after eating or drinking before you make a measurement. Morning—just after waking Time during the day: Evening—just before bed Name a slightly longer cycle of about 25 hours. measure the Time Temp. Time Temp. Time Temp. (determined by Dates

More recent research has shown, however, body tempera- Morning—just after waking Time during the day: Evening—just before bed monitoring the Name Time Temp. Time Temp. Time Temp. that the free-running period of the human ture of each of Dates length of darkness

Morning—just after waking Time during the day: Evening—just before bed Name clock is just slightly over 24 hours in both the members of Time Temp. Time Temp. Time Temp. Dates at night). young and older adults. their group at Morning—just after waking Time during the day: Evening—just before bed Name Time Temp. Time Temp. Time Temp. three different Dates

On a separate sheet of paper, calculate the average temperature for each person at each time of day. Graph In this activity, students will explore daily times during your results.

From Outerspace to Innerspace / Sleep and Daily Rhythms National Space Biomedical Research Institute 9 © 2000 Baylor College of Medicine cycles in themselves, animals and plants. the day over http://www.nsbri.org

6 From Outerspace to Innerspace / Sleep and Daily Rhythms © 2000 Baylor College of Medicine several days. The times should be selected in advance and temperatures taken at the same time each day. For example, just after waking in the morning, eight hours later, and just before going to bed in the evening. 6:00 am Other plants show Students can use a digital thermome- Bean leaves in the vertical position. ter under the tongue (being sure patterns of leaf to use a clean covering for each movements similar to measurement) or a thermometer that those that students they have at home. Measurements observe in beans. The should be recorded as degrees F in a sensitive mimosa, table like the one given on page 9. kelanchoe, and wood Have students calculate and graph the average temperature of the group sorrel are examples of plants that students can investigate. 100 9:00 am F) ° 99 Bean leaves in the horizontal position.

ure ( ure x Elise 98 x Jim 97 x Maria The famous botanist,

Average Body least two leaves in addition to the Temperat 96 cotyledons (fleshy seed leaves). Place Carolus Linneaus, the plants in a sunny window or in a noticed that flowers Time 1 Time 2 Time 3 Times of Day growth chamber with a light timer, of some plant species and have students note the orienta- opened at predictable for each time of day. Ideally, students tion of the larger leaves as early as times of the day. should make their first measurement possible in the morning and again Floral clocks, based just after waking and before eating later in the afternoon. In particular, or brushing their teeth. Similarly, students should notice whether the on his idea, still are for other measurements, students leaves are extended outward or planted in parks and should wait at least 15 minutes whether they are folded downward gardens. Traditionally, after eating, drinking or brushing toward the the “one o’clock” spot Activity 2 their teeth. stem. Have was planted with 1. Place bean plants in a sunny window, or under a grow light with a timer. Observe the leaves as early as possible in the morning and again later in the afternoon. Notice whether the them repeat leaves are facing to the side or facing upward, and draw your Leaves facing Leaves facing observations in the spaces below. to the side. upward. roses, “four o’clock” Day 1 Day 2 Day 3 What students will observe: body Early After- Early After- Early After- these observa- morning noon morning noon morning noon with hyacinths and temperature can be as much as tions over sev- 1–2 degrees lower in the very early eral days. “midnight,” with Time Time Time Time Time Time

2. Move the bean plants to inside a cupboard or to a dim corner of the room. Make your observations as before. pansies. morning than in the mid to late Day 1 Day 2 Day 3 Next, place the Early After- Early After- Early After- afternoon. This pattern is relatively morning noon morning noon morning noon plants in a consistent across individuals. darkened

Time Time Time Time Time Time Student results may not show this 3. Describe your observations on a separate sheet of paper. corner of the 10 National Space Biomedical Research Institute From Outerspace to Innerspace / Sleep and Daily Rhythms http://www.nsbri.org © 2000 Baylor College of Medicine much change due to variations in room or body temperature caused by activity. cupboard, and have students observe Results also will be affected by the and record the position of the leaves actual times at which temperature is at the same times as before. measured. What students will observe: Leaves Plant leaf movement. Grow young will be dropped toward the stem bean plants from seed or purchase very early in the day and fully them from a greenhouse. Plants extended (horizontal) later in the day, grown from seed should have at regardless of whether the plants

From Outerspace to Innerspace / Sleep and Daily Rhythms 7 © 2000 Baylor College of Medicine actually are exposed to the sun or length of time spent on the exercise artificial light. wheel, etc.) and the pattern or patterns that they discerned. Other cycles in living Note. Students may observe that 3. Discuss the results of the different organisms are longer plants’ stems curve toward the investigations with the class. Ask or shorter than 24 source of light. This movement is questions to prompt students’ hours. Examples of governed by chemicals inside the thinking. What did all of the cycles plant that cause cells on the side that you observed have in common? longer cycles include away from the light to lengthen more Did any of the patterns of behavior or fluctuation in levels than cells on the side facing the light. function occur without the presence of some human This phenomenon is different from of normal sunlight? Do you think hormones (which daily leaf movements, because it that something other than light is vary predictably results in permanent changes in the controlling the patterns that were over several weeks), shapes of the stems. observed? Help students reach the once-yearly flowering conclusion that something inside Animal behavior. If you have a each organism controls the observed by many plants, and hamster, or gerbil, with an exercise patterns. Point out that most annual migration wheel in your classroom, have organisms have internal timers that in a number of students observe and record the regulate many aspects of their lives. animal species. times of day when the rodent is Shorter cycles include active. Or have students observe and Extensions the cardiac cycle record the daily behaviors of other ● The University of California-San Diego animals, such as fish, crickets (will maintains a web site where students can (heart beat) and the chirp at approximately the same time monitor the daily behavior of a hamster, as internal sleep cycle each day) or birds, in the classroom. (stages of sleep). Students should record eating, resting and active times over several days to establish whether there is a Because many predictable pattern to the animals’ activities. Best results will be body processes are obtained if students make efforts to rhythmic, the observe without disturbing their effectiveness of subjects and if light exposures are certain drugs or kept on a consistent schedule. medicines will vary depending on the 2. After students have concluded time of day. their investigations, have each group present its observations to the class. Students should be able well as check the hamster's behavior for to describe the behavior or body the last few days. Have students log on at function that they observed, how and participate in the function (by measuring temperature, experiment.

Record the body temperature (temp.) in °F of each member of your group three times each day. For best results, take the first reading just after waking in the morning and the third reading just before going to sleep at night. Wait at least 15 minutes after eating or drinking before you make a measurement. Morning—just after waking Time during the day: Evening—just before bed Name Time Temp. Time Temp. Time Temp.

Dates

Morning—just after waking Time during the day: Evening—just before bed Name Time Temp. Time Temp. Time Temp.

Dates

Morning—just after waking Time during the day: Evening—just before bed Name Time Temp. Time Temp. Time Temp.

Dates

Morning—just after waking Time during the day: Evening—just before bed Name Time Temp. Time Temp. Time Temp.

Dates

On a separate sheet of paper, calculate the average temperature for each person at each time of day. Graph your results.

1. Place bean plants in a sunny window, or under a grow light with a timer. Observe the leaves as early as possible in the morning and again later in the afternoon. Notice whether the leaves are facing to the side or facing upward, and draw your Leaves facing Leaves facing observations in the spaces below. to the side. upward. Day 1 Day 2 Day 3 Early After- Early After- Early After- morning noon morning noon morning noon

Time Time Time Time Time Time

2. Move the bean plants to inside a cupboard or to a dim corner of the room. Make your observations as before. Day 1 Day 2 Day 3 Early After- Early After- Early After- morning noon morning noon morning noon

Time Time Time Time Time Time 3. Describe your observations on a separate sheet of paper.

10 National Space Biomedical Research Institute From Outerspace to Innerspace / Sleep and Daily Rhythms http://www.nsbri.org © 2000 Baylor College of Medicine CONCEPTS ● All mammals, including humans, and many other kinds of animals need sleep. ● Most people have regular patterns of sleeping and waking. OVERVIEW Students will collect data about their own sleep patterns and, if desired, those of members of their families. SCIENCE,, HEHEALTH & MATH SKILLS ● Observation ● Data collection ● Graphing ● Drawing conclusions ● Learning to identify and practice healthy behaviors 3. Sleepy Time Background Time Sleep takes up about one-third of our 30 minutes to conduct initial class lives. All mammals, including humans, discussion; 3–7 days for students to collect and most vertebrates sleep. Many aspects data on sleep times; 30 minutes for of sleep still are not understood. Once discussion of results All animals rest viewed as passive shutting-down between periods of of most body systems, sleep now is Materials activity. Sleep known to consist of several stages, Each student will need: patterns vary among each with differing levels of brain and ● log or journal different animals. muscle activity. ● copies of “Sleeping Patterns Graph” student sheet Rabbits, for example, Most of us sleep about the same number sleep for only a few of hours and wake at about the same Setup and Management minutes at a time. time each day, even without an alarm. Begin the activity with a discussion Dolphins have a Many, however, vary their sleep patterns involving the entire class. Working unique form of using external alarm clocks to meet school individually, students will collect data on sleeping: one half of or work schedules. Daily wake-up times in themselves and family members. They humans are governed by an internal clock, will share their results with other the dolphin brain consisting of about 10,000 nerve cells members of their groups. sleeps, while the located deep inside the brain. Even without other half continues any light or sound cues, most people sleep Procedure to be alert and and wake in cycles of close to 24 hours. 1. Challenge students to think about all wide awake. the different things that they do every Patterns of sleeping and waking vary by day. Let each student suggest one or age. For instance, newborns sleep 16–18 more activities and create a list on hours each day, including several naps. the board. By age one, children sleep 12–14 hours, including about two naps. Nine or ten 2. Now ask, What activities could you hours of sleep, without naps, is normal leave out of this list without affecting for children by age 12. Adults sleep about your health or how you feel? What eight hours per day. The urge to nap activities must stay on the list? Why in the afternoon is normal for teenagers do you think so? and adults, and most override this urge to sleep by remaining active. For some 3. Explain to students that they will be who may be in a sleep-promoting setting, examining one of the essential a nap may occur with possible hazardous activities on the list—sleep. Encourage consequences. students to share what they know

From Outerspace to Innerspace / Sleep and Daily Rhythms 11 © 2000 Baylor College of Medicine about sleep. For instance, when do look for similarities and differences. Scientists only are they usually sleep, how long do they Also help the students identify beginning to under- sleep, what makes them wake? patterns in their graphs. Ask stand why we sleep questions such as, Do most people go 4. Have each student create a journal, to bed and wake up at about the same and what happens or “Sleep Log,” to record the times he time each day? Did you feel when we sleep. Sleep or she goes to sleep and wakes daily. particularly sleepy on any day during consists of two The journal should include: waking this activity? Why or why not? Can different phases. One time; how student felt at waking; how you notice anything different about the phase, called non-REM student felt during the day (tired, well part of the graph corresponding to that sleep, is characterized rested, etc.); bed time; and how day? Who sleeps more—children or by slow brain activity, student felt at bedtime. If possible, grown-ups? What about very young time the activity so that students are children—do they have the same sleep no eye movement and able to compare weeknight and patterns as older children or adults? lack of muscle tone. weekend sleep patterns. Students may Another phase, Rapid want to ask other members of their Extensions Eye-Movement (REM) families to participate and record their ● In addition to recording sleeping and sleep, is characterized family members’ data as well. waking times, also have students record by an active brain, other essential activities, such as eating or 5. After 3–5 days, have students graph exercising, in their journals. bursts of eye their data on the “Sleeping Patterns ● Have students investigate the movements, and Graph.” Also sleeping habits of different kinds of paralyzed muscles Activity 3 have students animals (Where do they sleep and for (which makes it safe Color in the square representing your bed time and the square corresponding to your calculate the how long?, etc.). wake time for each day to dream!). recorded in your journal. Use a different ● color to fill in the average Have students create a sheet of squares between the bed and wake times. Record days of the Dreams are prevalent week and hours slept. number of paper with 24 squares by folding it in

Day of Hours the Week Slept hours of sleep half three times, followed by folding it during REM sleep. received by into thirds. Have them number the Scientists have each person squares with the hours of the day. Next, different ideas about included in ask students to draw the activity that Day Day Day Day Day Day Day why we dream. Some From Outerspace to Innerspace / Sleep and Daily Rhythms National Space Biomedical Research Institute 13 © 2000 Baylor College of Medicine http://www.nsbri.org the study. they did most during each hour of the day in the corresponding square. Have believe that the brain 6. Have students share and compare them count the number of squares consolidates needed their graphs and journals with other dedicated to sleeping, eating, playing, and erases unneeded members of their groups. Help them studying, etc. information during dreaming.

Color in the square representing your bed time and the square corresponding to your wake time for each day recorded in your journal. Use a different color to fill in the squares between the bed and wake times. Record days of the week and hours slept.

Day of Hours the Week Slept

Day Day Day Day Day Day Day

From Outerspace to Innerspace / Sleep and Daily Rhythms National Space Biomedical Research Institute 13 © 2000 Baylor College of Medicine http://www.nsbri.org CONCEPTS ● Sleeping and waking are governed by an internal clock. ● The internal “sleep” clock is influenced by external cues. ● Changes in schedules can conflict with the body’s internal clock. OVERVIEW Students will investigate the effects of changing their bedtimes on their sleep patterns. SCIENCE,, HEHEALTH & MATH SKILLS ● Predicting ● Observing ● Drawing conclusions 4. I’ve Got Rhythm Background Time As students discovered previously, most 30–60 minutes to conduct initial class A group of nerve cells people go to sleep and wake up at about discussion; 30–60 minutes to summarize that act as a biological the same times each day. This sleep cycle findings on the following day clock was first located is regulated inside the brain by a group of in the brains of house nerve cells that govern sleeping and Materials waking. These cells, which act as a timer, Each student will need: sparrows. Biological or “biological clock,” stay atuned to the ● copy of “Sleep Observations” sheet clocks now have been outside environment by receiving time identified in vertebrates, cues. Sunlight, a strong time cue, is Setup and Management such as mammals, detected by the retina (the part of the eye Conduct discussions of the activity with reptiles and some that has receptors for light), which sends the entire class. Students will carry out amphibians—and even messages to the brain. Daily exposure to their own investigations at home and light keeps the body’s sleep cycle report back the following day. invertebrates, such as synchronized to conditions outside. fruit flies, cockroaches, Procedure crickets and mollusks. Abrupt changes in sleeping times, such Day One “Clocks” also have as that due to air travel or a change in 1. Remind students of the results of the been found in single- work schedule, can cause difficulty with previous activities. Did the leaves of celled organisms, like falling asleep or staying awake, because the bean plants move in the same way mold and bacteria. external cues conflict with messages each day? How about the animals that being sent by the body’s internal clock. were observed? Did their behavior The brain may be signaling sleep, while show a daily pattern? Do you also do outside conditions may be saying be things at about the same time each Teenagers often active, it’s morning! It can take several day? Have students refer to the sleep have a sleep cycle days to adjust to a new time zone. Other journals they created. Do you think that is shifted so factors also can affect the sleep cycle. For some of the things you do are example, physical exercise, medicines, controlled by an internal clock? that their internally meal times and stimulants, (such as programmed sleeping caffeine in coffee, tea and soft drinks). 2. Explain to students that they time ends up will be investigating their own beginning around This activity allows students to biological clocks for sleeping and midnight. This may investigate their own internal clocks. waking. For one night, they will make it difficult for Students will try going to bed one hour change their bedtime to one hour them to get enough earlier than usual and observe the effects earlier than usual, and observe that it has on their abilities to fall asleep what happens. sleep if they do not immediately and on their waking times regulate light the next morning. 3. Mention the types of observations exposure carefully.

14 From Outerspace to Innerspace / Sleep and Daily Rhythms © 2000 Baylor College of Medicine Sleep disorders affect up to 70 million people in the US. Insomnia is a that students will make. For example, difficulty falling asleep early because sleep disorder which they should note whether it was easy their bodies were used to sleeping at a causes people to have or hard to fall asleep at the earlier later time. Likewise, students may difficulty staying time and whether they woke at their have woken at their usual times in the usual times the next morning. morning, even after receiving an extra asleep. Apnea is a Students also should notice how they hour of sleep, because of the disorder in which felt the next day—more sleepy, less programming of their internal clocks. people have difficulty sleepy, etc. breathing while asleep. 3. You may find that some students feel 4. Distribute copies of the student better after receiving the extra sleep. sheets on which students should Initiate a discussion of how much record their observations. Explain to sleep is typically obtained by children Astronauts frequently students that (see page 11) and how lack of sleep have difficulty sleeping. individual Activity 4 can impair performance on both This may be because

results will You will need to ask a family member or friend to mental and physical tasks. For help with this experiment. their internal clocks You will be going to bed one hour earlier than usual. Write your observations in vary from the spaces below. example, lack of sleep, like alcohol 1. What time did you go to bed? are not synchronized 2. What time did you fall asleep? (Have someone write this down for you.) person to 3. How did you feel when you went to bed early? intoxication, can make physical 4. What time did you wake the next morning? 5. How did you feel the next morning? to the light conditions person. If 6. In class, write a paragraph about your experiment in the space below. reactions slower. possible, have they experience. In each student Extensions addition, the stresses enlist the help ● Have students continue with the of space flight and

of a parent or Name earlier bedtimes for several days. Do they 16 National Space Biomedical Research Institute From Outerspace to Innerspace / Sleep and Daily Rhythms hectic work schedules http://www.nsbri.org © 2000 Baylor College of Medicine older brother eventually become used to the earlier can affect the quality or sister to record the actual time times? of astronauts’ sleep. that the student falls asleep. ● Invite another teacher or a parent Researchers are who has traveled across several time Day Two zones (across the continental US or to looking for ways to 1. Have students summarize their Europe, for example) to talk to the class address these problems observations by writing a short about how he or she felt physically for in space. Their results paragraph about how they felt as they the first one or two days in the new loca- will help many people tried to go to sleep at an earlier time. tion. Was it easy to sleep? Did he or she on Earth with sleep dis- Stimulate their thinking by asking have to make adjustments again after orders. questions, such as, Was it easier or returning home? more difficult than usual to go to sleep ● Invite a policeman, fireman or some- at a new time? Did you notice noises one else who routinely works a night and other people more or less? How shift to talk to the class about how he or In many places in the did you feel the next morning? Did you she has adapted to the stresses of a noc- US, everyone sets wake at your usual time? turnal work schedule. their clocks ahead ● Some animals are more active at one hour in the Spring 2. Have students share their paragraphs night than during the day. Have students with the rest of the class by reading investigate examples of nocturnal ani- and leaves them that them aloud or by posting them mals (bats, owls, luna moths, etc.) and way until the Fall. somewhere in the classroom. Initiate a report back to the class. What advan- Switching to Daylight class discussion of the results. Point tages might a nocturnal lifestyle have for Savings Time can out that some students may have had different kinds of animals? cause temporary adjustment problems for some people because their sleeping times are changed by one hour.

You will need to ask a family member or friend to help with this experiment. You will be going to bed one hour earlier than usual. Write your observations in the spaces below.

1. What time did you go to bed?

2. What time did you fall asleep? (Have someone write this down for you.) 3. How did you feel when you went to bed early? 4. What time did you wake the next morning? 5. How did you feel the next morning? 6. In class, write a paragraph about your experiment in the space below.

Name

16 National Space Biomedical Research Institute From Outerspace to Innerspace / Sleep and Daily Rhythms http://www.nsbri.org © 2000 Baylor College of Medicine CONCEPTS ● Time can be measured using the relative positions of the Earth and sun. OVERVIEW Students will make a sundial (shadow clock) and use it to tell time. SCIENCE,, HEHEALTH & MATH SKILLS ● Measuring ● Locating cardinal directions ● Making a model ● Observing ● Drawing conclusions

5. Shifting Shadows Background Time For a very long time, people relied on the 10 minutes for set-up; two 30–45 minute Over the course of position of the sun in the sky to estimate periods to conduct activity history, different civili- the time of day. Noon or midday was designated as the time when the sun Materials zations explained the was at its highest point. We now know, Each group will need: cycle of night and day of course, that the sun does not move ● flashlight in different ways. For across the sky as it appears. Rather, ● paper plate example, some ancient the Earth rotates as it revolves around ● coffee stirrer priests of India believed the sun. ● permanent marker the Earth to be sup- ● compass One of the earliest ways of measuring ported on 12 huge time used the predictable changes in Setup and Management pillars. At night time, shadows that occurred as the sun moved Place the materials in a central area for the sun was believed across the sky. Since shadows change Materials Managers to collect for their to pass underneath. predictably over the course of each day, groups. Have students work in groups of they can be used to estimate time. A stick four to conduct the activity. Aristotle, a Greek placed vertically in the ground probably philosopher, was was the first sundial. Simple sundials Procedure certain that the entire were used to tell time in Egypt more than Day One sky revolved around 3,000 years ago. 1. Ask students to observe while you use the Earth. This Earth- a flashlight and your hand to make a centered view of the In early times, an hour was calculated as shadow. Turn the light source off, then 1/12 of the period of daylight. Thus, ask Where is the shadow? Students universe was prevalent depending on the time of year, the length should understand that when an in Europe until the of the hours in the day varied. Now, we object is in front of a light source, it 16th century. divide each day into 24 equal hours, blocks the light, causing an area of Copernicus, a Polish which remain unchanged regardless of darkness—a shadow. Encourage the time of year. Today, time also is students to “play” with light and clergyman and standardized from place to place. Before shadows using the flashlights. scientist, is credited 1884, every locality set its clocks to the with providing the highest position of the sun (=noon). This 2. Challenge students to think about what world with a new led to considerable confusion, because happens to shadows outdoors as the theory of the solar every town ran on a different time. Now, position of the sun changes relative to system, in which the world is sectioned into 24 standard the Earth’s surface. Ask questions such time zones that are uniform. Each time as, Are shadows always the same planets (including zone accounts for 15 degrees longitude size? Why or why not? When are Earth) revolve and 60 minutes of Universal Time. shadows outside smallest? When are around the sun.

From Outerspace to Innerspace / Sleep and Daily Rhythms 17 © 2000 Baylor College of Medicine STANDARD TIME 1 2 3 4 5 6 7 8 9 10 11 12 123456789101112 am noon mid. they largest? Can we always In 1972, Universal see shadows outside? Have Time replaced students think about whether Greenwich Mean there is a pattern to the sizes Time as the standard of shadows made by the sun reference for telling (shadows are longest in the time. Universal Time, morning and evening, and shortest at mid-day). Using also referred to as W to E E to W flashlights and pencils, have subtract 24 hours add 24 hours International Atomic students make shadows of Time, is measured by different lengths. Ask them to Coordinated Universal Time (UTC) International Date Line formerly Greenwich Mean Time (GMT) (approximately) an atomic clock. The identify variables that affect atomic clock uses the the length of the shadows. extremely regular about the accuracy of the Shadow vibrations that occur 3. Challenge students to consider Clocks. Ask, How well did your whether there is a pattern to the way Shadow Clocks measure time, as within atoms to the positions of shadows change over compared to a watch or clock? Why do measure time. the course of a day. Do shadows stay you think the Shadow Clocks did (or in the same place all day? Explain to did not) measure time as accurately as students that they will be the other clocks? Also, ask students to investigating patterns in shadow consider when the Shadow Clocks movement. They will be using the might not be useful. Examples: night- patterns they discover to solve a time (too dark), when skies are cloudy practical problem: telling time. (no shadows), at different times of the year (shadow pattern will be different, 4. Distribute copies of the “Shadow so clocks might not predict time Clock” sheet to students. Following the correctly), in different locations instructions given on the sheet for Day (pattern will change if other location is A sundial based on One, they will work in groups to create at a different latitude). drawings from children Shadow Clocks (sundials). across the US will travel 3. Brainstorm with students on ways to Mars aboard NASA's 5. Note that if the observations are made to improve the Shadow Clocks. Mars Surveyor 2001 during normal school hours, the Have them look on the Internet or lander. Inscribed with clocks will be calibrated only for a in the library to find other sundials. portion of the total day. As an the words “Two alternative, consider having students Variations Worlds, One Sun,” the also calibrate their Shadow Clocks at ● Have students try using shadow sundial will be 3 inches home, so that the clocks will be length to predict the time. (about 8 cm ) square, useful for the full range of daylight. ● Have students think about why time and weigh just over 2 zones that account for a one-hour time ounces (60 grams). Day Two difference are separated by 15° of longi- Image courtesy of NASA. 1. Students will use their Shadow Clocks tude. in a new location and compare times of ● Using a globe or an atlas, have stu- day, as measured by their Shadow dents figure out what time it would be in Clocks, to times shown by a watch or London, Los Angeles, Honolulu and The position that the clock. Each group must use a compass Moscow, if it were 8:00 a.m. in St. Louis, sun appears to have in to orient their Shadow Clocks in the Missouri. the sky depends on same direction as on Day One. ● To learn more about sundials, have where you are on the students check the NASA Web site at 2. After students have completed both .

Your group will need: Disposable paper plate Compass Coffee stirrer Permanent marker Lines that you DAY ONE will draw each hour N 1. Turn the plate upside down and write the letter 12:00 “N” on one edge of the plate to mark the side 11:00 1:00 that should face North. 10:00 2:00

2. With the plate still turned upside-down, 9:00 3:00 make a very small hole in the center using 8:00 the tip of a pencil. Push the coffee stirrer 4:00 through the plate about one-half to one 7:00 5:00 inch. Put the plate back on the table. The 6:00 6:00 stirrer should “stand” straight up. 3. Take the plate outside and place it in a Insert coffee stirrer vertically into the sunny place. center of the paper plate. 4. Using the compass, position the plate so that the “N” is facing North. (If it is windy outside, you may need to tape the plate down). 5. Using the marker, carefully trace the line created by the shadow of the coffee stirrer on the plate and label the time as shown above. Side view with 6. At one-hour intervals, repeat steps 4–5. coffee stirrer inserted 7. After you have made as many one-hour readings as possible, bring your Shadow Clock back inside. DAY TWO 1. Now you will test the accuracy of your Shadow Clock. Take the clock outside to a new location. 2. Use a compass to position the plate so that the “N” is facing North. 3. Observe where the shadow line falls on the plate. Based on the markings you already have made, estimate the current time as accurately as possible. 4. Compare your estimate to the time as measured by a watch or clock. How close were you? 5. On a separate sheet, describe why the Shadow Clock worked or didn’t work. Does the Shadow Clock have any advantages over a mechanical clock? Does it have any disadvantages?

From Outerspace to Innerspace / Sleep and Daily Rhythms National Space Biomedical Research Institute 19 © 2000 Baylor College of Medicine http://www.nsbri.org CONCEPTS ● Many different factors affect the quality of sleep. ● Astronauts traveling in space experience many disruptions of normal sleep patterns. OVERVIEW Language arts activity in which students brainstorm about when they have had difficulty sleeping, read about how astronauts sleep in space, and write about unusual places in which they have slept. SCIENCE,, HEHEALTH & MATH SKILLS ● Identifying common elements ● Making extensions to new situations 6. Sleeping in Space Background Time Many different factors can affect the quality 10 minutes for set-up; 30–60 minutes to of sleep. All of us have had difficulty conduct activity sleeping at one time or another. Excitement, Students can do anxiety or stress, consumption of Materials several things to make stimulants, unusual surroundings, noises, Each student or group of students will sure they will be rested travel across time zones, or changes in daily need: and ready to perform schedules can make sleeping difficult. ● copies of “Catching Zzzzz’s” and “Are well in school. Insomnia is the word used to describe an You Sleeping?” student pages ongoing inability to get enough sleep to feel • Avoid soft drinks or rested during the day. More than 50% of Setup and Management foods with caffeine Americans suffer from occasional bouts of Conduct this activity with the entire class. (for example, insomnia or other sleep disorders. Students may read the story, Catching chocolate, some soft Zzzzz’s, individually, or they make work Astronauts probably experience more in teams. drinks, coffee, tea). disruptions of normal sleep patterns than • Stick to a regular anyone else. The intense work schedule, Procedure schedule for going to unusual surroundings, cramped work 1. Ask students to remember an bed and waking up, quarters, stress and excitement of being in occasion when they had difficulty and get some bright space all can make sleeping difficult. Space sleeping. Have them share their motion sickness also can contribute to experiences with the rest of the class, light in the morning. sleeping problems. In addition, the normal and list the experiences on the board • Get some light 24-hour pattern of light and darkness that or on an overhead. Scenarios exercise in the late provides a time cue to the body’s internal suggested by students might include: afternoon (but not sleeping and waking cycle is absent. the night before an exciting event, such as a birthday party; trying to in the evening Since lack of sleep can seriously affect sleep in the car during a long trip; or before going to bed). performance on physical and mental tasks, being wakened by strange or • Recognize that, helping astronauts overcome sleeping frightening noises at night. on average, most problems is a priority. Several days before launching into space, crew members are 2. Encourage students to think students need at exposed to bright lights at specific times, a carefully about the list and to least nine to ten controlled environment and programmed identify common elements among hours of sleep per meal periods to help reset their bodies’ the events. Such elements could night, and plan internal clocks to match the schedules that include: sleeping in places other schedules will be followed in space. Research to help than home; sleeping before or accordingly. astronauts sleep better also helps people on after unusual events; sleeping when Earth with similar problems. one’s physical state is not normal

20 From Outerspace to Innerspace / Sleep and Daily Rhythms © 2000 Baylor College of Medicine (sick with an itchy rash, etc.). complete the reading and writing Why do we sleep? extensions on their own or by working Scientists still are 3. Mention to together in small groups. investigating this students that Activity 6 question. Some they will Have you ever slept in a sleeping bag? Most people sleep in sleeping bags when they go 5. Provide an opportunity for students to camping or when they sleep over at a friend’s house. Astronauts also sleep in sleeping bags when they are in space. people believe that be reading Each time they sleep on a space craft, astronauts zip themselves into special sleeping bags. share their work by having them read The bags have to be fastened to something, because otherwise the sleeping astronauts would float around inside the space shuttle, due to the lack of gravity. Usually, the astronauts are fastened inside sleep helps the body about how separate sleeping spaces. Each space has a light for the paragraphs that they created as reading and a sliding door that can be closed.

The astronauts can face in any direction when they astronauts are sleeping. Some of the sleeping compartments face part of the writing activity on page 23, recover from activities the top of the space shuttle. One of the compartments faces the floor. Each bed in the compartments is just a sleep in padded board. The astronauts do not need a thick or by displaying the paragraphs mattress, because they float freely inside the space during waking hours craft and are comfortable in any position. space. Ask, Astronauts have many things to think about when somewhere in class. they are living and working in space. This can make it and also helps in the hard to sleep. Astronauts do not experience normal Astronauts in their sleeping spaces on periods of daylight and night time, either. This also can shuttle mission STS-68. (NASA photo) Do you think make it hard to sleep. Sometimes, part of the crew sleeps while the other crew members work. If light and sounds make it hard for them to sleep, formation of astronauts the astronauts can wear blindfolds and ear muffs. 22 National Space Biomedical Research Institute From Outerspace to Innerspace / Sleep and Daily Rhythms http://www.nsbri.org © 2000 Baylor College of Medicine Extensions can sleep as ● Have students create drawings to memories. Some well in space as they can at home? accompany their paragraphs on sleep- animals also might What might be different about ing. sleep to save energy sleeping in space? After students ● Encourage students to access during hours when it have offered their comments, NASA-associated sites on the World is too dark or too distribute copies Wide Web. NASA’s homepage is a good dangerous to hunt of the “Catching Zzzzz’s” and place to start . for food. “Are You Sleeping?” pages. ● Encourage students to find out about other occupations in which the sleeping 4. Students may read the essay and circumstances might be unusual. Sleeplessness diminishes mental and physical performance. In addition, a sleepy body is more susceptible to the effects of drugs and alcohol. Sleepiness can build up day, after day, after day, creating a sleep “debt” that may be hard to “pay back.”

Have you ever slept in a sleeping bag? Most people sleep in sleeping bags when they go camping or when they sleep over at a friend’s house. Astronauts also sleep in sleeping bags when they are in space.

Each time they sleep on a space craft, astronauts zip themselves into special sleeping bags. The bags have to be fastened to something, because otherwise the sleeping astronauts would float around inside the space shuttle, due to the lack of gravity. Usually, the astronauts are fastened inside separate sleeping spaces. Each space has a light for reading and a sliding door that can be closed.

The astronauts can face in any direction when they are sleeping. Some of the sleeping compartments face the top of the space shuttle. One of the compartments faces the floor. Each bed in the compartments is just a padded board. The astronauts do not need a thick mattress, because they float freely inside the space craft and are comfortable in any position.

Astronauts have many things to think about when they are living and working in space. This can make it hard to sleep. Astronauts do not experience normal Astronauts in their sleeping spaces on periods of daylight and night time, either. This also can shuttle mission STS-68. (NASA photo) make it hard to sleep. Sometimes, part of the crew sleeps while the other crew members work. If light and sounds make it hard for them to sleep, the astronauts can wear blindfolds and ear muffs.

1. Make a list of the ways in which sleeping in 2. Make a list of the ways in which sleeping in space is just like sleeping on Earth. space is different from sleeping on Earth.

3. In the space below or on a separate sheet, write a paragraph about the most unusual place in which you ever slept. Include answers to the following questions: Where did you sleep? How well did you sleep? Would you like to sleep there every day?

From Outerspace to Innerspace / Sleep and Daily Rhythms National Space Biomedical Research Institute 23 © 2000 Baylor College of Medicine http://www.nsbri.org CONCEPTS ● Many organisms show daily cycles of activities or functions. ● Daily cycles (also called circadian rhythms) are about 24 hours long—the same as one rotation of the Earth. ● Circadian rhythms in living things are controlled by internal biological clocks that are set to local environmental conditions. ● The timing of when humans sleep and wake is governed by an internal clock. ● People can have difficulty sleeping if external conditions change suddenly and no longer agree with the settings of their internal clocks. OVERVIEW Summative/assessment activity: students will review concepts about sleep and daily cycles using a fun poem, and will create their own illustrated rhymes. SCIENCE,, HEHEALTH & MATH SKILLS ● Integrating information ● Drawing conclusions 7. Twenty-Four Hours a Day Background Time Cycles and rhythms can be found in all 10 minutes for set-up; 45 minutes to organisms on Earth. Many of these cycles conduct activity are synchronized to the 24-hour cycle of the Earth’s rotation about its axis. Materials Each student or group will need: The timing of when people are asleep and ● copy of “Tick-Tock, Tick-Tock” sheet awake is determined to a large extent by ● paper to create a poem an internal clock. Environmental cues, ● markers, crayons, etc., to illustrate particularly light, keep the clock new poem synchronized to external conditions. The clock itself, however, will continue to run Setup and Management on approximate 24-hour cycles, even Conduct a summary discussion of the without changes in the environment. major concepts in the unit by reciting the poem on page 26 with the class. Students The human cycle of sleeping and waking should work independently or in small can become disrupted if external groups for the remainder of the activity. conditions, particularly light, change. This happens when travelers move across Procedure time zones or when astronauts travel 1. Review the major concepts to which in space. students were exposed in this unit, as outlined in the Background section Space life scientists are looking for ways of this activity. Activity 7 to help astronauts achieve the sleep they

need to function well under the stresses 2. Read or have Tick-tock, Tick-tock, Tick-tock, Tick-tock. Did you know that you are a clock?

Just like the sundial’s shadow-line Barn owls hunt when the day is done. of long-term space flight. Their research students read your inside clock can measure time. They rarely ever see the sun. It tells you when it’s time to eat, also will help solve sleep-related problems the poem, and even when to go to sleep! But you are not the only one who know it’s time for work or fun.

for people on Earth. Tick-Tock, The plants can tell it’s time to bloom. They know that springtime’s coming soon! How’d they do it? What can it be? Most birds at dawn begin to sing — The answer’s in their cells, you see. Tick-Tock. without alarms that ring-a-ling. People, plants and animals all — Talk about the have inside clocks that send a call. The clocks tune in to many cues like, when it’s dark, it’s time to snooze.

concepts in Frogs know when to ribbit and croak, So now you know you are a clock, to chase some flies, or take a soak! Shout it out loud: Tick-tock, Tick-tock!

3. Have students create their own

24 From Outerspace to Innerspace / Sleep and Daily Rhythms © 2000 Baylor College of Medicine illustrated poems. Several options own to complete the poem; or are possible. • Share the first few lines of each •Distribute the poem to students. verse and have the students •After reading the poem, let students complete the verses with their own write their own poems on sleep and inspirations; or biological clocks; or • Devise your own way to inspire • Read a few of the verses to get students to express their knowledge students started, and then suggest about biological rhythms and clocks that they write verses of their in verse.

Tick-tock, Tick-tock, Tick-tock, Tick-tock. Did you know that you are a clock?

Just like the sundial’s shadow-line Barn owls hunt when the day is done. your inside clock can measure time. They rarely ever see the sun.

It tells you when it’s time to eat, and even when to go to sleep!

But you are not the only one who know it’s time for work or fun.

The plants can tell it’s time to bloom. They know that springtime’s coming soon! How’d they do it? What can it be? Most birds at dawn begin to sing — The answer’s in their cells, you see. without alarms that ring-a-ling. People, plants and animals all — have inside clocks that send a call.

The clocks tune in to many cues like, when it’s dark, it’s time to snooze.

Frogs know when to ribbit and croak, So now you know you are a clock, to chase some flies, or take a soak! Shout it out loud: Tick-tock, Tick-tock!