Insufficient sleep raises mental‑health risk for teens and late bedtime spikes health hazards

A systematic review and meta‑analysis of 73 studies from 2002‑2018, involving participants aged 10‑19 across Asia, North America, Australia and Europe, found that adolescents who sleep less than the recommended eight to ten hours are significantly more likely to experience poorer mood. The overall odds of feeling mentally worse were 1.55 times higher for short‑sleepers, with the strongest effect on positive mood (odds 2.02) and a weaker but still elevated risk for anxiety (odds 1.41).

A separate U.S. study by Stanford University reported that the clock time at which people go to bed also matters. Researchers identified a critical threshold hour after which the risk of depression, anxiety and other health problems rises sharply, suggesting that aligning sleep with an earlier bedtime can reduce long‑term medical risk even if total sleep duration is adequate.