In another study, Duffy et al. (2011) reported that the intrinsic circadian period was significantly shorter in women (24 h 5 min ± 12 min) than in men (24 h 11 min ± 12 min). Davis,
Darrow, and Menaker (1983) showed in hamsters, Mesocricetus auratus, that during entrainment to a 24 h light:dark cycle (LD 14:10), females began their daily activity earlier than males.