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Circadian Rhythm Disorders

What are disorders? • results from a conflict between the pattern of Circadian rhythm disorders are disruptions in the sleep and wakefulness between the internal biological circadian rhythm—a name given to the “internal and that of a new zone. Individuals find it body clock” that regulates the (approximately) 24- hard to adjust and function optimally in the new time of biological processes in and . zone. Eastward travel is more difficult than westward The term “circadian” comes from Latin meaning travel because it is easier to delay sleep than to “around the .” advance sleep. The key feature of circadian rhythm disorders is a • affects people who continuous or occasional disruption of sleep patterns. frequently rotate shifts or work at night. Work The disruption results from either a malfunction in schedules conflicts with the body’s natural circadian the “internal body clock” or a mismatch between the rhythm and some individuals have difficulty adjusting “internal body clock” and the external environment to the change. Shift work disorder is identified by a regarding the timing and duration of sleep. As a result constant or recurrent pattern of sleep interruption of the circadian mismatch, individuals with these related to the work schedule that results in disorders usually complain of insomnia at certain or excessive sleepiness. and excessive sleepiness at other times of the day, The diagnosis of circadian rhythm disorders is resulting in work, school, or social impairment. challenging and often requires a consultation with a The following is a brief description of the more sleep specialist. Keeping a detailed sleep and a common circadian rhythm disorders. sleep dairy for one to two is essential. It is also important to exclude other sleep and medical disorders, • Delayed Sleep Phase Disorder is a circadian rhythm including , which often mimics delayed sleep disorder most common in adolescents and young phase disorder. Sleep diaries are often complemented adults whose “night ” tendencies delay sleep by , a method of estimating sleep and wake onset – often until 2 a.m. or later. If allowed to sleep using a wrist motion monitor for a of days to in late (often as late as 3 p.m.), weeks. Overnight and daytime sleep testing may be does not occur. However, earlier wake up times can required. Sleep studies must be tailored to address lead to daytime sleepiness and impaired work and the sleep pattern of the individual. This may require school performance. These individuals are often that testing be performed at unconventional times, for perceived as lazy, unmotivated, or poor performers example, an ‘overnight’ might be performed who are chronically tardy for morning obligations. during the day in a shift worker. People with delayed sleep phase syndrome are often most alert, productive, and creative late at night. Treatment Options • Advanced Sleep Phase Disorder is usually seen Treatment options for circadian rhythm disorders in the elderly. This disorder is identified by regular vary based on the type of disorder and the degree early evening bedtimes (6 p.m. – 9 p.m.) and early to which it affects the individual’s quality of life. morning awakenings (2 a.m. – 5 a.m.). People with Individualizing the treatment of patients with circadian advanced sleep phase syndrome are “morning larks” rhythm disorders improves the chance of success. and typically complain of early morning awakening or Treatment options include: insomnia as well as sleepiness in the late afternoon continued on back page or early evening. Circadian Rhythm Disorders, continued

Behavior Therapy such as maintaining regular sleep- Medications such as , wake-promoting wake times, avoiding naps, engaging in a regular agents, and short-term sleep aids may be used to routine of exercise, and avoiding caffeine, nicotine, and adjust and maintain the sleep-wake cycle to the stimulating activities within several of bedtime desired schedule. is important in the treatment of circadian rhythm Chronotherapy is a progressive advancement or disorders. People with delayed sleep phase syndrome delay (1-2 hours per day) of sleep time depending should minimize exposure to light in the evening and on the type and the severity of the disorder. This type during the night by reducing indoor illumination and of therapy requires a firm commitment on the part avoiding bright TV and computer screens. Those with of the patient and caregiver as it is can take weeks advanced sleep phase syndrome should increase light to successfully shift the sleep-wake cycle. Once the exposure in the evenings by keeping lights on in the desired schedule is achieved, a regular sleep-wake home or spending time outdoors. schedule is maintained. Bright is used to advance or delay sleep.

The timing of this treatment is critical and requires Resources guidance from a sleep specialist. Bright light therapy works by resetting the . A high intensity The Cleveland Clinic Guide to Sleep Disorders by Nancy light (10,000 lux) is required and the duration and Foldvary-Schaefer, DO timing of exposure varies from thirty to sixty minutes.