Sleep-wake rhythm disorders involve abnormal circadian rhythms. When the body’s circadian clock functions normally, sleep occurs at predictable times that align with light exposure, mealtimes and other recurring daily patterns. In people with sleep-wake rhythm disorders, sleep periods don’t seem to follow any set pattern.
Like other circadian rhythm sleep disorders, symptoms of sleep-wake rhythm disorders include disordered sleep rhythms. People with sleep-wake rhythm disorders often cannot fall asleep at bedtime and may not sleep for long stretches at night. They may nap frequently throughout the day but cannot sustain a regular sleep pattern. They generally experience daytime fatigue and have difficulties with job performance and carrying out basic daily tasks.
Irregular sleep-wake rhythm disorder is a rare neurological condition characterized by the lack of a defined circadian rhythm. People with this disorder may get enough sleep over a 24-hour period, but don’t have a predictable sleep pattern.
Non-24 hour sleep-wake disorder is a rare circadian rhythm disorder involving a circadian rhythm that doesn’t align with a 24-hour schedule. People with non-24 hour sleep-wake rhythm disorder have a circadian cycle that gets progressively longer, so sleep periods and wake-up times occur later and later, causing difficulties with work, school and daily activities.
What causes Sleep-Wake Rhythm Disorders?
Sleep-wake rhythm disorders are neurological conditions that involve the brain’s regulation of sleep patterns. They’re seen more often in people with neurological disorders like dementia.
Because light exposure helps dictate the body’s biological rhythms, blind individuals or people with low exposure to light have a higher risk of developing these disorders.
People may display signs of sleep-wake rhythm disorders as they age. Research suggests that melatonin production decreases with age, so people over 70 have a higher risk of dysregulated circadian patterns.
Sleep-wake rhythm disorders are diagnosed through a combination of a detailed health history, sleep tracking, and laboratory tests. A sleep specialist generally evaluates sleep habits and patterns that you record in a sleep diary. In general, a pattern of disturbed sleep rhythms over a period of at least six weeks signals sleep-wake rhythm disorder.
Because self-reported sleep data recorded in a diary may not be comprehensive or accurate, a physician may order additional sleep evaluations. Sleep activity may be tracked using actigraphy, which involves wearing a device that measures movement during sleep to provide a more detailed view of sleep-wake patterns. A polysomnogram may also be used to track brain, heart, and lung activity overnight. Finally, samples of blood or urine may be requested to check for abnormal hormone levels.
Physicians often recommend behavioral changes as the first line of treatment for sleep-wake rhythm disorders. These changes may include:
Going to bed and waking up at the same time each day
Chronotherapy: Gradually moving your bedtime and wake-up time to your desired schedule
Avoiding light exposure for one hour before bed
Maintaining a completely dark bedroom
Additionally, supplemental melatonin and light therapy (intentional exposure to bright light for at least one hour each morning) have been proven to help people with sleep-wake rhythm disorders.