This disorder consists of symptoms of insomnia or excessive sleepiness that occur as transient phenomena in relation to work schedules. The work is usually scheduled during the habitual hours of sleep. The sleep complaint typically consists of an inability to maintain a normal sleep duration when the major sleep episode is begun in the morning (6 to 8AM) after a night shift. Usually the reduction in sleep length amounts to one to four hours. As a result, the sleep period is perceived as unsatisfactory and unrefreshing. The insomnia appears despite attempts to optimize environmental conditions for sleep.

The condition usually persists for the duration of the work shift period. Patients with this disorder have reported reduced alertness, negative social consequences, marital disharmony, impaired social relationships, and increased irritability. Adaptation rarely occurs despite many years of night shift work, in part, because of the resumption of full daytime activities and nighttime sleep during weekends and vacations. Full sleep episodes during the daytime become more difficult with increasing age.