Apple Watch study shows majority of Americans not getting enough sleep

New research suggests that humans may need more sleep during the colder months. An analysis of people who participated in sleep studies found that people had more REM (rapid eye movement) sleep in the winter months. While the total sleep time in winter is about an hour longer than in summer, this result wasn't considered to be statistically significant. Yet researchers found that REM sleep, which is directly linked to the biological clock that's affected by the change of light, was 30 minutes longer in winter than in summer.