Secular changes in sleep duration among Australian adults, 1992-2006

Objective: To determine whether sleep duration of Australian adults has declined over recent years. Design: Analysis of nationally representative data from repeated cross-sectional time-use surveys conducted in 1992, 1997 and 2006. Setting: Private households in Australia. Participants: Respondents aged 15 years and over (N=21 195) who completed time-use diaries over two consecutive days. Main outcome measure: Change in sleep duration by sociodemographic group. Results: Mean sleep duration was 8h 20 min in 1992, 8h 33 min in 1997, and 8h 30 min in 2006 (SEM for all years, 1 min). After adjustment for sampling during weekends and different seasons, there was no significant change in sleep duration from 1992 to 2006 (adjusted difference, 2 min; 95% CI, - 2 to 5 min; P=0.33). The only significant decreases in sleep duration were observed in people aged 65 years and over (adjusted difference, 12 min; 95% CI, 4-19 min; P<0.001), people with no income (adjusted difference, 17 min; 95% CI, 7-27 min; P=0.001) and male carers (adjusted difference, 31 min; 95% CI, 9-53 min; P=0.002), although people in these groups reported over 8h sleep on average. Conclusions: Most Australian adults were not sleeping less in 2006 than they did in 1992. Public health concerns over declining sleep duration do not appear to be warranted. Investigation of possible changes in quality of sleep is required.