Dying to sleep F 28 and couldeven bedeadly Getting toolittle sleepcanimpairbodyandbrain, ofslumberscience suggests that stinting on sleep night after ( plaques Alzheimer’sdisease to mice in loss sleep links study new a now, And animals.laboratory and people in p.85) 2/8/03, (SN: lives shorter and 46) p. 5; p. 1/3/09, (SN: diabetes p. 195), heart disease, high blood pressure, obesity (SN: 11/17/07, p. 318; SN: 4/1/06, Studies have linked chronic sleep loss to deadly. even serious, more far be can help anyone getapromotion. And nodding off at work probably won’t well-rested peers (SN: 09/09/06, p. 174 ). their as well as perform or learn don’t irritable when tired, too. Sleepy students get adults and children Older nap. a ing such as a toddler’s crabbiness after miss- are immediate, obvious and unpleasant, of University intheNetherlands.Groningen the at neuroscientist a Meerlo, Peter says sleep,” without night’sgood sleep. a get regularly who those than health their losing of risk higher a face enough snooze don’t who people that shows also research Recent death’s arrival. up speed might sleep losing that suggest that theycansleepwhenthey’redead. floor are told that only losers snooze and dance the than hay the hit rather would ductive, wasteful downtime. People who many surveys ofAmericans, it’s sleep. period, something has to give. Judging by SN: 10/24/09, p. 11). And some evidence

Other penalties for staying up too late Some of the consequences of lost sleep do can’t we that is certain is “What benefitssleep’s about data new But unpro- as some by regarded is Sleep | science news science cram everything into one 24-hour to order In enough. long seem don’t just days people, many or

|

October 24, 2009 | SN: 1/19/08,SN:

dying tosleep

another becomesaroadmenace. while fine drive might person sleepy one why also but performance, driving affects deprivation sleep how only not Now,scientists tryingareunderstandto estimate. conservative a probably year, each deaths 1,550 and injuries nonfatal 40,000 about in result crashes driving drowsy- that estimates Administration National Highway Transportation Safety The consequences: fatal or injurious ate seen inpeoplewhodevelop diabetes. responded to glucose, mirroring a change study one in people way the changed usual than night per sleep less hours two just getting of week A hormones. hunger-promoting increase and 14) p. 10/11/08, (SN: blood the in chemicals shown to increase levels of inflammatory tal disorderssuchasdepression. of which may predispose people to men- namedHeather sitsbehindwheelthe of much sleepisneededtorepay the debt. how out find to and life, real in rience expe - people deprivation sleep chronic of kind the to responds brain the how about more learn to is experiments the of aim The days. two for hours 10 to up five nights, then let the volunteers sleep teers’ time in bed to four hours a night for Medicine inPhiladelphia. the University of Pennsylvania School of at lab Dinges’ David in occurrence mon com- a is wheel the behind off Nodding Too tired to function permanent night may cause long-term And And lack of sleep can also have - immedi Just one night of short sleep has been In the dimly lit laboratory, lit volunteer dimly a the In Dinges and his colleagues limit volun- By Tina HesmanSaey By Tina — changes changes in the brain, some — maybe even

colliding withtheslow-moving truck. darkness. Heather quickly brakes to avoid the back of a large cargo truck looms in the bend, a by. Suddenly, around flash poles illuminated only by her headlights. White road dark a on hour per miles 60 over just at along buzzes car virtual her that to her head. She pushes the accelerator so a driving simulator with electrodes taped national highw Source: 2002srvey ofdistracted anddro Hour while driving P Drowsy driving Outcome ofnoddingoffwhiledriving awake, some crashed. While most of those surveyed were startled drivers have fallen asleep behind the wheel. ercentage ofpeoplewhoha T 37% otal W s sleptthenightbeforedrivingdrowsy andered outoflane 5 hr Crossed center

16–20 Ran offtheroad 18% s Star W ≤ 4hr Got inacrash 6 hr as honk ay traffic safetyadministration , 16% tled a by s 21–29 s age 40% 26% 24% Other ed at wa More than one-third of U.S. line ke 30–45 17% 41% www.sciencenews.org 17% 2% 6% 9% 10% 19% 7 hr ≥ 8hr ve noddedoff 46–64 33% 42% s wsy driving/ s 30% 65+ 92%

facing Page: tommy leonardi Sleepy volunteers put pedal to the metal in a University of Pennsylvania driving simulator. Lab technician Christopher Jones demon- strates: electrodes on his head register brain waves on an EEG and the simulator measures his driving performance. 30 ofslumberscience people resist makingsleepy mistakes. that affect those genes and help ordinary researchers may be able to develop drugs littleso sleep,despite functioning brain figuring out whichgenes keep Heather’s become mush when deprived of sleep. By don’t brains whose people rare few a of with sleep loss. But Heather may be one mance of daily activities can deteriorate people’sperfor most severely how just from herwell-rested showing. deteriorated hasn’t tests other and tor simula - driving the on performance her she’sto,and when supposed notoff ded nod- dizzy,”hasn’t and Heather headed light- little “a tired, feeling despite But sleep. of bouts brief even detect can researchers that so and movements waves eye brain her monitoring are to sleepdeprivation. ences that may affect people’s responses differ genetic of study a for shut-eye forgoing is She sleep.” my get always “I says. she night,” all up stay never “I schedule. sleep curtailed this to used isn’t She reports. heavy,” she feel limbs “Mysleep. of hours four just gotten has ing factor in more than 20 percent of the perform whendeprived ofsleep. will howthey predicting well at notgood One constant is that people are generally says. Dinges sleep, less on well function they that convinced are short-sleepers contrary,many the to evidence Despite sleepy.while function to ability his ing into thebackofatruck. tor. He woke up to find that he’d smashed simula- the driving while asleep fell he as he does when well-rested. On this day, dim lighting,“I’m functioning,” hesays. tempered,” he says. But despite the lab’s short- and things process to able not zombie, a like be to going was I thought “I days. several for night each sleep of horrible after missing out on four hours feel to expected He semester. a of end tinely pulls all-nighters, especially at the

James, an architecture student, rou student, architecture James,an shown have lab Dinges’ in tests The head Heather’s on electrodes The For each of the past four nights, Heather Driving Driving while drowsy was a - contribut James is certainly not alone in misjudg- well as not but Functioningperhaps, | science news science

|

October 24, 2009 |

dying tosleep - - -

ihs dw fo a aeae f 7.8 of hours in1998. average an from down nights, 7.1sleeping weekend reported on hours either. On average, respondents in 2009 sleep isn’t being recovered on weekends, lost That 1998. in percent 12 with pared weeknights,on hours six than com- less slept they that said participants survey of percent 20 2009, In habits. sleep of dation, which conducts periodic surveys Foun- Sleep National the to according before, ever than less sleeping are cans don’tpeople fact, Ameri- In getenough. and other illnesses. disease heart diabetes,obesity, of risk to eight hours each night carries the least diseases show that sleeping about seven ing on the person. But studies of various depend- night, per sleep of hours 10 as much as and 11) 9/12/09,p. (SN: hours six as little as includes range “normal” The night. each need people sleep of No magic number exists for the amount How much is enough Dinges says.Dinges grossly different brain activity profiles,” restricted of sleep.“People days walkingare witharound five with change doesn’t tests response-time and tion ple’s performance on a variety of atten- to as “type 1s,” like Heather. Those peo- Then there are the people Dinges refers is cut short over the course of five days. vigilant and sharp on tests as their sleep steady decline in their ability to remain of sleep. Others, like James, show a slow, fall apart after missing just a few hours people some that found studies,has he his In says. Dinges deprivation, sleep to responses individual James’ er’s and fold, theresearchersfound. a cell phone increased crash risks three- dialing and makeup on putting reading, contrast, In near-crash. or crash a have driver was four to six times more likely to drivers’ actions for about a year. A drowsy recorded then and sensors and cameras Blacksburg. The team fitted 100 cars with studyTechVirginia byat researchers in a in recorded near-crashes and crashes Humans are the only animals that that animals only the are Humans many is, sleep for need the Whatever No one could have predicted Heath- predicted have could one No a cluster of conditions of cluster a symptoms of “the metabolic syndrome,” have to likely more were long-sleepers risk for health problems. Both short- and at also are average than more far sleep with eachhouroflost sleep. increasing index mass body with obese, of sleep per night) were more likely to be adults (those who got less than five hours in year study,last The hours.published 10 pared with children who slept more than com obese be to likely as twice nearly are night a hours 10 than less sleep who studies worldwide showed that children or high-carbohydrate foods. caffeinated beverages and eat high-sugar drink smoke, to likely more were also ties, exercise or have sex. Short-sleepers eat healthy diets, engage in leisure activi- efficiently,and well work they that say to more or hours eight slept who people six hours a night were also less likely than crucial forhealth,” Van Cautersays. sleep, like exercise and proper feeding, is to bother with sleep. “We are ignoring that have tostay awake,’ ‘you him, tell and remote the him give television, the of front in rat a put not can- “YouChicago. of University the at researcher sleep VanEveCauter,a says sleep, of themselves deprive willingly shows another study led by researchers by led study another shows average, on hours seven sleep who ple also at higher risk for diabetes than peo- reported. researchers the too, did nightly sleep of hours six than less getting those of third a nearly and symptoms, the had night a hours eight than more sleeping But almost a quarter of people regularly collaborators reported last year in and Pittsburgh of University the from researchers symptoms, such had cent per 17 only night, each sleep of hours presage diabetes andheartdisease. and reduced sensitivity to insulin levels cholesterol high pressure, blood Some data suggest that people who who people that suggest data Some population several of analysis An Those respondents who slept less than People think that they are just too busy Both short- and long-sleepers were long-sleepers and short- Both eight to seven get who people Among Sleep, also showed that short-sleeping ” shesays. www.sciencenews.org

—

including high including

— Sleep.

that - -

facing page: Sebastian Kaulitzki/shutterstock (body image), T. dubÉ Brain Effects of sleep deprivation Cognitive impairment, declines in memory and judgment, and brain chemical changes that can lead to depression Losing sleep, even for one night, can trigger a Attention and sleep flood of changes throughout the body. Scientists don’t fully understand how the sleep-starved 15.0 3.0 body goes awry, but many studies find clear 4 hrs* 4 hrs* s 10.0 2.0 relationships between sleep and the health and ror 6 hrs* 6 hrs* Er 5.0

ted sleepiness ted 1.0 function of body systems. 8 hrs* 8 hrs* 0.0 0.0 Thymus *Time in bed *Time in bed Immune system 2 468 10 12 14 Self-repor 2 46810 12 14 impairment Days of sleep restriction Days of sleep restriction People’s performance on an attention test declines Stomach with sleep loss (left), even though they don’t feel much Increased hunger sleepier (right). source: Van Dongen et al./Sleep 2003 Hunger and sleep

More Heart Higher disease risk, irregular heart beat Blood pressure and sleep 12

Self-reported hunger 10 Less 7 4.5 0 8 Hours of sleep 6

source: Schmid et al./ J. Sleep Research 2008 4 2 ive-year systolic increase F 0 Pancreas < 4 4–5 5–6 6–7 > 7 Insulin resistance Average hours of sleep per night

and higher risk of source: Knutson et al./Archives type 2 diabetes of Internal Medicine 2009

Fat layer Joints Increased risk of obesity Increased Body mass index and sleep inflammation, which 30 can lead to athero- sclerosis (artery Men Women 29 hardening) and rheu- matoid arthritis 28 BMI 27

26 Metabolism Higher risk of “the metabolic syndrome,” which includes 25 high blood pressure and cholesterol and < 5 5–7 7–8 ≥ 8 reduced insulin sensitivity, sometimes Average hours of sleep per night leading to diabetes and heart disease source: Patel et al./International Journal of Obesity 2009 The metabolic syndrome 30 Muscle 25 Decreased 20 reaction time 15 and accuracy 10 5 ercent with syndrome

P 0 < 6 6–7 7–8 > 8 Average hours of sleep

source: Hall et al./Sleep 2008

www.sciencenews.org October 24, 2009 | science news | 31 science of slumber | dying to sleep at Columbia University and published in Sleep in 2007. Sleeping about seven to eight hours per night Most people are fooling themselves if carries the least risk of obesity, diabetes, heart they think they need less sleep than aver- disease and other illnesses. Whatever the need for age, Van Cauter says. A study of healthy young adults, published in 2005 in sleep is, many people are not getting enough. Sleep, seems to back her up. Volunteers were given the opportunity to get some vation (SN: 3/24/2007, p. 190). PER3, a many brain functions. The research- extra shut-eye for three days in a study cousin of genes involved in the circadian ers didn’t find any changes in the rats’ conducted by researchers at Harvard clock, which governs daily body rhythms brains after a single night of sleep loss, Medical School in Boston and the Uni- including meal times and bedtimes, but after a week of getting shortchanged, versity of Surrey in Guildford, England. comes in two common forms. The more the rats’ brains became less sensitive to Everybody slept more the first day of the common form contains four repeats of serotonin. Such changes could make study, but by day three, people who nor- a segment of the gene, and a less-com- rats, and people, more prone to devel- mally sleep more than nine hours a day mon variant contains five repeats of oping depression, Meerlo says. had maxed out their sleep. People who that segment. People who have inher- As bad as that news potentially is, normally slept less continued to catch ited two copies of the longer form tend Meerlo has worse news. Even after he let extra z’s. The researchers concluded that to be morning people, while people with the rats sleep in on the weekend, their people with shorter sleep times probably two copies of the shorter form tend to be brains still didn’t respond to serotonin carry a bigger sleep debt than others, one night owls. as effectively as before sleep deprivation, that couldn’t be paid back in three days. When their circadian alertness level Meerlo and his colleagues reported last was at its lowest daily point, sleep- year in Sleep. Sleeping in your genes deprived people with the long form per- Even more disturbing is the finding Researchers would dearly love to know formed worse on some tasks than people from a study of sleep deprivation in rats what makes people like Heather resis- with the short gene, researchers led by conducted by researchers at North- tant to the attention-degrading effects Derk-Jan Dijk at the University of Surrey western University in Evanston, Ill. The of sleep loss. (Though scientists don’t reported in 2008 in Sleep. Many research- researchers found that rats deprived of know whether these people’s bodies ers interpret that result to mean that the about 35 hours of sleep over five days — an hold up against sleep deprivation as well long form of the gene makes people more extreme sleep loss — didn’t make up that as their brains do.) Studies of twins sug- vulnerable to sleep deprivation. lost sleep when given three days to do gest that a large part of the resistance But people with different forms of the nothing but sleep. The result, reported in is genetic: Identical twins’ responses PER3 gene didn’t show any differences the Proceedings of the National Academy to sleep deprivation are as similar to in responses to partial sleep depriva- of Sciences in 2007, suggests that chronic each other as an individual’s results in tion over five nights in a study by Dinges sleep loss may actually prevent the body repeated tests. and colleagues published online June 11 from sleeping more to recover. Previously, researchers reported that a in PLoS ONE. The two results can’t be “That would limit your ability to make gene called PERIOD3, or PER3, might be directly compared, because the volun- up your sleep debt,” Van Cauter says. involved in the response to sleep depri- teers in Dinges’ study were asleep dur- And sleep deficit is a debt you can’t ing the time of day that the Surrey group afford, Meerlo says. “One night of missed Wake up, sleepy gene Despite being found differences in performance. So the sleep isn’t going to kill you,” he says, “but “morning people,” those with a long form of the jury is still out on whether PER3 protects the danger is that if you’re not getting PER3 gene perform worse on memory tasks when sleepy than people with the short form. some people against the effects of sleep enough sleep night after night, small deprivation, and researchers are hunting cumulative effects could add up.” Genes and sleep for other genes that may contribute to So while you may be dying to stay up 25 differences in sensitivity to sleep loss. one more hour to finish reading that 20 chapter or reach one more level on that

15 No snooze, you lose video game, researchers say that in the All the consequences for chronically long run, you could be inching closer to 10 missing out on slumber aren’t yet known, a state of permanent rest. s rect responses 5 Cor but some studies suggest sleeping too Short form Long form 0 little for too long can change the brain. Explore more 10pm 12am 2am 4am 6am 8am 10am In a study in rats, Meerlo examined ss The National Sleep Foundation’s Time of test serotonin — a brain chemical thought to 2009 Sleep in America Poll: http:// source: J.A. Groeger et al./sleep 2008 be important in sleep, depression and bit.ly/18WpId

32 | science news | October 24, 2009 www.sciencenews.org