Research suggests that how often people check social media − and how emotionally engaged they are with it − can influence sleep even more than how much time they spend online.

When a child takes a 1 milligram dose of melatonin, the hormone quickly enters their bloodstream, signaling to the brain that it’s time for sleep. Melatonin reaches levels in the blood that can be ...

Unhealthy habits associated with working late or night shifts can induce cancer, the WHO says, and make other health conditions more likely.