While prior studies have examined sleep across the lifecourse, few studies have investigated sleep around the birth of a child, one of the most important events to cause sleep deprivation. This study investigates changes in sleep hours and quality, paying attention to differences by gender and partnership status. Using the UK Household Longitudinal Study, we follow approximately 1,000 participants as they transition into parenthood in a three-year window. We use OLS and logistic regression to analyze changes in sleep hours and sleep quality. Results suggest that women's sleep is reduced by an average of 0.7 hours (42 min) on becoming a mother. Whilst before parenthood women sleep more than men, after childbirth women and men sleep similar amounts. Cohabiting men experience a greater reduction in sleep by around 0.5 hours (30 min) than married men, to the level similar to women, suggesting that new cohabiting fathers may experience more sleep disturbances.