What is it? When a person's biological clock gets out of sync with accepted norms, sleep disorders arise. In delayed sleep phase insomnia, the person falls asleep and awakens later than required for normal activities such as work and school. Once the person falls asleep, however, his or her sleep is restful and uninterrupted. Awakening at an acceptable time, even with an alarm clock, is extremely difficult. Resulting symptoms include daytime sleepiness, particularly in the morning; fatigue; impaired memory and concentration; low productivity, particularly in the morning.
How common is it? Relatively rare (fewer than 2 percent of those seeking help at sleep disorder clinics are diagnosed with it). It frequently begins during childhood and is most common during adolescence. These symptoms are also seen in people suffering from depression.
What's the treatment? Two therapies are used:
- Chronotherapy—This technique re-sets the person's biological clock by having the person stay up and awaken three hours later each day over a several-day period until their sleep and awake times are in sync with others. During that time they cannot nap, and once they've changed their schedule they must maintain it even on weekends (varying it by no more than an hour) to prevent the return of the problem.
- Light therapy—This technique uses bright lights (as bright as sunlight) for two hours in the morning and avoids bright light for several hours before bedtime to shift the sleep-wake cycle. Special light boxes for this purpose are available through medical supply sources and are similar to those used to treat people with seasonal affective disorder.