Research library
Sleep insights
Peer-reviewed sleep research, translated into plain English.
SleepFree
How do you reset your circadian rhythm? A trial shifted night owls by 2 hours
What resets your circadian rhythm is when light reaches your eyes, not how much you get: morning light pulls the clock earlier, evening light pushes it later.
2019Sep 2026
SleepFree
Does alcohol affect REM or deep sleep? Both, in opposite directions
Alcohol affects REM and deep sleep in opposite directions: REM drops from about two drinks, deep sleep rises early and falls later in the night.
2025Aug 2026