Pregnancy induces an earlier chronotype in both mice and women

Wrist actigraphy was obtained for two weeks before conception and then throughout pregnancy. Chronotype was measured by determining the time of sleep onset from the actigraphy profile of each 24-hour period (12 PM to 12 PM the next day) during the first (gestational weeks 4 through 13), second (weeks 14 through 27) and third trimesters (week 28 until delivery).