Circadian Rhythm Sleep Disorders.

Delayed sleep phase syndrome (DSPS) is best treated by first using behaviorally scheduled sleeping and arising times to realign the patient's sleep-wake cycle to local time and then by keeping the cycle in synchrony with local time by adherence to a strict daily schedule. Adjunct treatment with morning light exposure or evening melatonin may be useful, and sometimes necessary, to help establish and maintain the new schedule. Coexisting psychiatric or medical illness should be treated before or simultaneously with DSPS. Advanced sleep phase syndrome is rare, and though no treatment has been well studied, evening light exposure and morning melatonin may be helpful. Non-24-hour sleep-wake cycle is common in the blind but occurs rarely in normally sighted persons. Chronic use of evening melatonin may be necessary for these patients to maintain a useful, conventionally timed sleep-wake cycle. Irregular sleep-wake cycles are probably common in persons with multiple handicaps or dementia. Chronic use of melatonin in the evening and exposure to morning light may be useful. Jet lag varies from a minor annoyance to a source of severe impairment of vigilance in the workplace or while driving. Treatment strategies include avoiding naps in the new time zone, staying on the home schedule during short stays, assuming the schedule of the new time zone during longer stays, taking evening melatonin in the new time zone and on return, and using a short-term bedtime sedative in the new time zone and on return. Shift-work sleep disorder affects most night-shift workers, who never fully adjust to trying to sleep in the daytime after their work shifts, often fall asleep while at work, and are at increased risk of development of heart disease and gastrointestinal disorders. Splitting their sleep between after-work morning naps and before-work late-afternoon naps should enable them to get more sleep. Brighter light in the workplace and sleeping in complete darkness may also be of benefit. Long-term use of sedatives is inadvisable for shift workers.