Objectives The aim of this study was to examine the relationship between occupation and sleep duration, sleepiness, insufficient sleep, and insomnia in day and shift workers (including night work and watches).

Methods The study was population-based and cross-sectional, and relied on self-administered questionnaires. It was conducted as part of the 1997–1999 Hordaland Health Study in collaboration with the Norwegian National Health Screening Service. Aged 40–45 years, 7782 participants answered a sleep questionnaire, reporting their occupation and whether or not they were employed in shift work.

Results Our study found differences in sleep duration during the working week between occupational groups; in both shift and day workers. Craft workers, plant operators, and drivers slept less than leaders, and non-personal and personal service workers. Within some occupations (leaders, personal service workers, and plant operators), shift workers slept less than day workers. The mean sleep duration of shift workers was 15 minutes shorter than that of day workers. Rise times, but not bedtimes, were earlier in craft-and construction workers, plant operators, and drivers than in leaders and non-personal and personal service workers, particularly day workers. When adjusted for shift work and working hours – compared to leaders – craft workers, plant operators, and drivers had an increased risk of daytime sleepiness (odds ratio 1.5, 1.8, and 1.8 respectively) and of falling asleep at work (odds ratio 1.6, 2.1 and 2.0 respectively). Shift workers had an increased risk of falling asleep at work and insomnia.

Conclusions Occupation has separate effects on sleep duration and sleep-related problems, independent of the effects of shift work.

Key terms bedtime; Hordaland Health Study; insomnia; insufficient sleep; occupation; rise time; shift work; sleep duration; sleep-related problem; sleepiness