Disorders of the Sleep Wake Cycle

Disorders of the sleep wake cycle occur when a person's internal clock loses sync with natural light and dark cycles. Normal sleep-wake cycles are at least 24 hours long, with sleeping patterns following the dark and light times of day. Sleep-wake cycle disorders can be extrinsic (caused by external factors) or intrinsic (caused by internal abnormalities).

Time Zone Change Syndrome

Time zone change syndrome, also known as jet lag, occurs when a person travels across multiple time zones. Symptoms may include general fatigue, moodiness, headaches, decreased appetite or other gastrointestinal problems, and depending on the direction of travel, either insomnia or excessive sleepiness. According to the American Academy of Sleep Medicine, symptoms can be more severe or prolonged in the elderly and in people traveling eastward. To avoid these symptoms, begin adjusting sleep times to the time zone being traveled to. Travelers should get plenty of sunlight and avoid taking a nap when arriving at the destination.

Shift Work Disorder

People who work during normal sleeping hours often suffer from shift work disorder. Common symptoms of shift work disorder include sleepiness during work hours, difficulty sleeping during off-hours, lethargy, headaches and decreased concentration, according to the Cleveland Clinic. The effects of this disorder can be reduced by minimizing exposure to light during sleeping hours, avoiding consecutive night shifts and rotating shift schedules. Get at least seven to eight hours of sleep every day and stick to a consistent sleep schedule.

Advanced Sleep Phase Syndrome

People with advanced sleep phase syndrome (ASPS) tend to go to sleep and wake up at unusually early hours. It occurs most commonly in the elderly and post-menopausal women. People with ASPS are unable to stay up late at night or stay asleep past early morning hours, but can still have stable sleep schedules. According to the Cleveland Clinic, waking and sleeping cycles can be readjusted gradually to a later hour using bright-light and chronotherapy treatments.

Delayed Sleep Phase Syndrome

Delayed sleep phase syndrome (DSPS) is the opposite of advanced sleep phase syndrome---rather than being unable to stay awake later, people with DSPS suffer from nightly insomnia and an inability to wake up early in the morning. Like most other forms of insomnia, around half of DSPS sufferers also show signs of depression. According to Stanford University's website on circadian rhythm disorders, most people with DSPS stay awake until 2 a.m. or later, getting less sleep during the week due to work or school schedules, and sleeping deeply for longer periods of time on weekends. In most cases, DSPS first appears during adolescence, often after periods of late-night activity. Aside from over-the-counter and prescription sleep aids, treatments are similar to those for ASPS, including bright-light therapy and chronotherapy.

Irregular Sleep-Wake Cycle

Unlike those with ASPS and DSPS, people with an irregular sleep-wake cycle lack any consistent sleeping cycle or rhythm. The American Academy for Sleep Medicine lists chronic insomnia and excessive fatigue as symptoms of irregular sleep-wake cycle. People with little exposure to light cues or regularly scheduled activity may be at higher risk for the disorder. Rather than sleeping for one continuous period, people with irregular cycles tend to take frequent naps throughout the day. Lifestyle and schedule changes, bright-light therapy and nightly melatonin treatments may aid in readjusting an irregular sleep-wake cycle.

References

• Stanford University
• American Academy of Sleep Medicine
• Cleveland Clinic