Epidemiology of bedtime, arising time, and time in bed: analysis of age, gender, and ethnicity.

This study investigated the epidemiology of bedtime (BT), arising time (AT), and time in bed (TIB) as a function of age, gender, and ethnicity. Sleep diary data were analyzed for 746 randomly selected community participants. This sample was comprised of 364 men (48.8%) and 382 women (51.2%), 532 Caucasians (71.3%) and 214 African Americans (28.7%), and participant ages ranged from 20 to 98 years. Regression analyses showed a main effect of age on subjective BT, AT, and TIB. The addition of gender and ethnicity to the regression model added significant variance for TIB, but not BT or AT. In general, BT declined across the lifespan, but AT showed a quadratic pattern that peaked in young adulthood, was stable in the middle years, and peaked again in the later years. This age-related combination of BT and AT resulted in greater TIB for older adults than other age groups. Women spent significantly greater TIB than men, and African Americans spent significantly more TIB than Caucasians. These results suggest that there are distinct behavioral sleep patterns associated with age and, in the case of TIB, gender and ethnicity. These patterns may have significant clinical implications, particularly with respect to age.