Pre-sleep behaviour in normal subjects

Behaviour in the 2-h period before sleep onset was evaluated in 90 subjects with normal sleep/wake habits using an anonymous self-report questionnaire. This determined the timing of events from the initial preparation for sleep. The nature of the pre-sleep environment, the level of physical activity, and patterns of feeding behaviour were recorded together with self-ratings of tiredness, mood and security. Estimated sleep duration and sleep quality were determined. Ninety of 120 subjects responded. Sleep 'preparatory latency', from the time of initial sleep preparation to sleep onset, was 77 +/- 48 min; bed time to sleep onset time (sleep latency) was 41 +/- 42 min; lights out to sleep onset latency was 26 +/- 45 min. The estimated total sleep time was 7 +/- 1 h. In the pre-sleep period, mean noise and illumination levels were low and environmental temperature rating was at the median point on a very cold-very hot scale (mean scale scores: 23, 28 and 50, respectively). All subjects went to the bathroom before going to bed. Twenty-five percent of normal subjects had a snack or meal in the 2-h period before sleep onset. Sixty percentage recorded setting an alarm, 27% had a bath or shower, 23% checked door locks or windows and 49% read in bed. Nine percent of subjects slept with a cat on the bed. Humans, like other animal species, show a complex behavioural sequence in the 2-h period before falling asleep. A constant environment with limited metabolic activity may predispose to thermoregulatory changes prior to sleep onset.