Field notes · Sleep and recovery
Alcohol and sleep: what one drink really does
The nightcap works, in the sense that you fall asleep faster. That is where the good news ends.
Dai Manuel · Coach Moose · Vancouver
What happens
Alcohol is a sedative, so it shortens the time to fall asleep. As your body processes it, sleep in the second half of the night becomes lighter and more broken, and REM sleep is reduced. That is why you wake at 3am after a couple of glasses and why the morning feels flat even after eight hours in bed.
The more you drink, and the closer to bedtime, the bigger the effect. But even moderate amounts show up.
The two-week experiment
Do not take my word for it. Go two weeks without drinking on weeknights and notice how you wake up. Most men I coach are surprised, and a few are annoyed at how obvious the difference is.
Canada's Guidance on Alcohol and Health, updated in 2023, puts low risk at two drinks or fewer a week. I am not going to tell you what to do with that. I am telling you it exists.
Common questions
- Does alcohol ruin sleep quality?
- Alcohol shortens the time to fall asleep but reduces REM sleep and makes the second half of the night lighter and more broken, especially at higher doses and closer to bedtime.
- How long before bed should I stop drinking?
- The less and the earlier the better. Many sleep experts suggest stopping at least three to four hours before bed, but the clearest improvement comes from not drinking on weeknights at all.
Sources
- Alcohol and sleep I: effects on normal sleep. Ebrahim, Shapiro, Williams and Fenwick, Alcoholism: Clinical and Experimental Research, 2013.
- Canada's Guidance on Alcohol and Health. Canadian Centre on Substance Use and Addiction, 2023.