G. Jean-louis et al., Sleep duration, illumination, and activity patterns in a population sample: Effects of gender and ethnicity, BIOL PSYCHI, 47(10), 2000, pp. 921-927
Background: Current knowledge of the population's sleep durations emanates
primarily from questionnaires and laboratory studies. Using Actillumes, we
investigated whether self-reported sleep durations were indicative of a pop
ulation decline in sleep duration. We also explored illumination and activi
ty patterns.
Methods: San Diego adults (n = 273, age ranger 40-64) were recruited throug
h random telephone calls and were monitored at home while engaging in usual
daily routines.
Results: Volunteers slept an average of 6.22 hours and received an average
of 554 lux (environmental illumination). The timing of sleep, illumination,
and activity occurred at 2:44, 12:57, and 13:43, respectively. Irrespectiv
e of ethnicity, age, and time reference, men received greater illumination
than did women, but this gender effect was not independent of work status.
Women and men exhibited a similar circadian activity profile; however, wome
n exhibited better sleep-wake patterns. Interactions between gender and eth
nicity suggested worse sleep-wake patterns among minority men. An age-relat
ed decline in activity was found, but no age trend in sleep duration or ill
umination patterns was observed.
Conclusions: This study showed an objective population decline in sleep dur
ation. Sociodemographic effects should be considered in analyses of sleep-w
ake patterns and illumination exposures. (C) 2000 Society of Biological Psy
chiatry.