brain, spinal cord, and nerve disorders
Circadian Rhythm Sleep Disorders
Causes of Circadian Rhythm Sleep Disorders
Causes of circadian rhythm sleep disorders may be internal or external. Internal causesinclude the following: Damage to the brain—for example, due to a brain infection ( Encephalitis ), Insensitivity to the cycle of night and day External causesinclude the following: Jet lag (especially when traveling from west to east) Working irregular shifts on a regular basis Frequently going to bed and getting up at different times Being confined to bed for a long time Blindness or not being exposed to sunlight for long periods of time Taking certain drugs Sleep-wake reversals are common among people who are hospitalized because they are often awakened during the night and because their eyes are not exposed to sunlight long enough during the day. There are several types of circadian rhythm disorders. Jet lag disorderis caused by rapid travel across more than two time zones. Shift work disordervaries in severity depending on How often shifts change How much they change Whether they make sleep and wake times earlier or later How many consecutive nights are worked How long the shift lasts Always working night or evening shifts and keeping the same bed times on days off is preferable. However, even then, daytime noise and light may interfere with sleep. Also, workers often shorten their sleep time and sleep at different times on days off to participate in social or family events. Delayed sleep phase disorderoccurs when people consistently go to sleep and awaken late (for example, go to sleep at 3 AM and wake up at 10 AM or as late as 1 PM). This syndrome is more common among adolescents and young adults. People with delayed sleep phase disorder cannot fall asleep earlier even if they try. Advanced sleep phase disorderoccurs when people consistently fall asleep and awaken early and cannot change this pattern. It is more common among older people. People with advanced sleep phase disorder cannot stay awake until later times even if they try. Non–24-hour sleep-wake syndromeoccurs when the sleep-wake cycle changes every day. The length of the sleep-wake cycle remains the same, but it is more than 24 hours. Thus, sleep and wake times are delayed by 1 to 2 hours each day. This syndrome is much less common and tends to occur in blind people. 