Current criteria for circadian rhythm sleep disorders require a mismatch between the endogenous circadian sleep tendency and exogenous environmental requirements for sleep timing. To examine the prevalence of circadian rhythm sleep disorders by DSM-IV criteria, sleep complaints and objectively-measured sleep timing were sampled in a population aged 40-64 years. Randomly selected volunteers were interviewed concerning sleep complaints. Then, objective sleep timing was estimated from wrist activity recordings and environmental illumination data. In this age group, advance-related complaints (trouble staying awake until bedtime and troubled by waking up early in the morning) were found together in 7.4%. Less prevalent were delay-related complaints reported together in 3.1% (trouble falling asleep and trouble waking up in the morning). However, no significant correlations or clusters were found pairing these sleep complaints with recorded sleep timing. The distributions of objectively-recorded lights-out times and arising times were consistently later than the questionnaire-reported times. Thus, complaints suggesting circadian rhythm advance or delay mismatches were common, but evidently such complaints do not usually correspond with objective abnormalities of observed sleep timing.