Aetiology
Non-24-hour sleep-wake rhythm disorder is believed to be caused by an internal desynchronization of the body’s circadian rhythm, or “body clock”. It is typically seen in individuals who are completely blind, as they are unable to perceive light, which normally helps to keep the body’s internal clock in sync. It can also occur in individuals with impaired vision.
Diagnosis
A diagnosis of non-24-hour sleep-wake rhythm disorder is typically made based on a detailed medical history and physical exam. The patient’s sleep patterns, as well as any other medical conditions, will also be taken into account. Other tests, such as a sleep study, may be ordered to confirm the diagnosis.
Differential diagnosis
Non-24-hour sleep-wake rhythm disorder must be differentiated from other circadian rhythm disorders, such as delayed sleep phase syndrome, advanced sleep phase syndrome, irregular sleep-wake syndrome, and jet lag disorder.
Treatment
Treatment for non-24-hour sleep-wake rhythm disorder typically includes light therapy and/or melatonin supplementation. Other treatments, such as cognitive-behavioral therapy, may also be recommended.
Prognosis
The prognosis for non-24-hour sleep-wake rhythm disorder is generally good with treatment. It is important to note, however, that the condition is chronic, meaning that it is likely to persist for a long time, even with treatment.