Sleep-wake disorders occur when the body’s internal clock does not work properly or is out of sync with the surrounding environment.
The body has an internal timing system called the circadian system that regulates daily behavior and bodily functions through cycles called circadian rhythms. Circadian rhythms influence things such as sleeping and eating patterns, body temperature, and the production of certain hormones. These rhythms repeat approximately every 24 hours.
A particular part of the brain called the suprachiasmatic nucleus generates circadian rhythms. Exposure to light also affects the timing of the rhythms. Normally, circadian rhythms are in sync with the surrounding environment, which helps people stay awake during the daytime and fall asleep at night. Circadian rhythm sleep-wake disorders occur when the synchronization between circadian rhythms and the external environment is lost or when the circadian system itself is dysfunctional.
There are several different types of sleep-wake disorders. All involve problems falling asleep or staying awake at desired or socially appropriate times. Jet lag disorder and shift work disorder are the 2 most common sleep-wake disorders, and they are caused by misalignment of circadian rhythms with the surrounding environment. Jet lag disorder involves excessive sleepiness or difficulty falling asleep that is due to quickly crossing multiple time zones. Shift work disorder involves problems with sleepiness or alertness related to an irregular or untraditional work schedule. The other types of sleep-wake disorders are characterized by abnormalities of the circadian system itself, and these disorders are delayed sleep-wake phase disorder, advanced sleep-wake phase disorder, non–24-hour sleep-wake rhythm disorder, and irregular sleep-wake rhythm disorder.
Diagnosis of sleep-wake disorders is based on the type of sleep problems present and the timing and setting in which they occur. To better understand your sleep patterns, a health care practitioner may ask you to fill out a sleep diary and wear a motion sensor for up to 14 days. Keeping a sleep diary means writing down the timing of your sleep and the amount of sleep you obtain each day. Actigraphy involves wearing a motion sensor on your wrist to track your sleep and activity patterns throughout the day. Usually, a sleep study is not needed to diagnose sleep-wake disorders, but it is sometimes used to make sure you do not have additional sleep problems.
The specific treatment of sleep-wake disorders depends on the type of sleep-wake disorder. In general, strategically timed exposure to light and following a sleep schedule are behavioral changes that may be helpful. Melatonin is a hormone produced by the body that regulates sleep-wake cycles, and melatonin supplements may be used in some situations to help align the body’s circadian rhythms with the outside environment. Other medications may also be used, depending on the scenario, to either promote wakefulness or facilitate sleep.
American Academy of Sleep Medicinewww.sleepeducation.org
Sources: American Academy of Sleep Medicine
Zee PC, Attarian H, Videnovic A. Circadian rhythm abnormalities. Continuum (Minneap Minn). 2013;19(1):132-147.
Muth CC. Sleep-Wake Disorders. JAMA. 2016;316(21):2322. doi:10.1001/jama.2016.17785