This was a cross-sectional study to examine the different associations of age and sleep duration with sex steroid hormones and sexual activities in 531 Asian Chinese men aged between 29 and 72 years old. Sleep duration and sexual activities were evaluated through a self-administered questionnaire, and total testosterone (T), sex hormone-binding globulin (SHBG), estradiol (E2), and dehydroepiandrosterone sulfate (DHEAS) were measured by established immunoassay methods in a single blood sample collected between 8:00 and 11:00 am. Bioavailable T (BioT) was calculated using the Vermeulen formula. Age was a major determinant of sleep, sex steroid hormones, and sexual activities in men. BioT, DHEAS, coital frequency, masturbation, and sleep duration declined with age. On the other hand, SHBG and E2 increased with age. Sleep duration, independently of age, aerobic exercise, and body fat, was positively associated with T and BioT, but not with DHEAS, E2, or any of the sexual activities studied. Men who masturbated had higher levels of both T and BioT. DHEAS was significantly associated with coital frequency and desire for sex. The present study showed that besides age, sleep duration was associated with androgen concentrations in men, and thus the evaluation of sleep hygiene may be beneficial in the management of men with low androgen concentrations. DHEAS may be independently associated with some sexual functions in men.