Biopsychobehavioral correlates of insomnia, III: Polygraphic findings of sleep difficulty and their relationship to psychopathology.

The effects of age and sex on sleep-wakefulness patterns and the relationship between these patterns and psychopathology are described in 150 adults with a primary complaint of insomnia and 100 controls who did not have any complaints of sleep difficulty. Within the insomniac subjects, the degree of difficulty in staying asleep was positively correlated with age. The primary difference between the insomniacs and controls was the insomniacs' greater difficulty in initially falling asleep or returning to sleep once having awakened during the night. Also, in terms of the distribution of wakefulness, insomniacs had significantly greater mean values for wakefulness during each of the first three to four hours of the night. In insomniacs the severity of sleep difficulty and the degree of psychopathology were positively related. Finally, various sleep difficulty and MMPI variables reliably discriminated insomniacs from controls.