Sleep-readiness signals in insomniacs and good sleepers.

Sleep is preceded by physiological and behavioural events that inform the subject that it is time to sleep. Our hypothesis is that insomniacs do not adequately recognize such signals, thus missing the best time to go to bed. Eighty-seven chronic insomniac participants and 76 age-matched good sleeper controls were recruited. Semi-structured interviews focused on three aspects of nocturnal sleep: features, habitual activities and signals that they usually rely on in order to decide their readiness to sleep. The results showed that insomniacs relied more than good sleepers on external signals (time) than on bodily ones to decide to go to sleep.