Jet lag syndrome and circadian disorders of the sleep-wake cycle

Circadian rhythm sleep disorders (CRSDs) are related to alterations in circadian timekeeping system or misalignment between endogenous circadian rhythm and exogenous factors, such as desidered or socially required time schedules, that affect sleep timing or duration. The most commonly observed are jet lag disorder, advanced and delayed sleep phase disorder, free-running disorder, and irregular sleep-wake disorder. The clinical picture may include sleep loss, fatigue, cognitive and vigilance deterioration and hormonal and gastrointestinal distress. Therapeutic management involves interventions aimed at mitigating symptoms affecting sleep and vigilance, and facilitating adaptation to the desired circadian schedule. Appropriately, scheduled bright and dim light exposure and melatonin administration are the main therapeutic tools together with sleep hygiene and chronotherapy. Excessive daytime sleepiness may benefit from short strategic naps and caffeine, whereas bedtime hypnotics may have favorable effect on sleep latency and maintenance. Melatonin and appropriately timed bright light exposure are effective in enhancing new time zone adaption, particularly for stays longer than 3-5 days, whereas short stopover may not benefit.