A new study investigatds the long-term effect of sleeping time on health and mortality and concludes that sleeping before 10 pm (22:00) or past midnight is associated with increased diseases and mortality. Sleeping at about 11 pm (23:00) appears to be optimal [Wang et al. 2021].
Wang et al. 2021 "Association of bedtime with mortality and major cardiovascular events: an analysis of 112,198 individuals from 21 countries in the PURE study" Sleep Med, 2021 Feb 5;80:265-272. doi: 10.1016/j.sleep.2021.01.057.