REM stages and one REM stage. Ideally, you repeatedly cycle through each stage. Learn how long each stage lasts.

“When we’re sleeping ... with people.” If someone consistently wakes up tired, they first need to start tracking their sleep patterns— when they get into bed every night and when they ...

Sleeping during the day is not as restorative as it is at night. You can only get used to night work to a limited extent. Your body cannot be completely reprogrammed, he says.