The short answer
Alcohol helps you fall asleep faster and deepens sleep in the first half of the night, but as it wears off, sleep becomes broken and shallow in the second half, with less REM sleep. The net effect, especially with more than a drink or two, is worse sleep. The NHS advises no alcohol for at least 6 hours before bed.
Strong evidence
Several good randomised trials or a solid review of them agree, or very large long-term studies are backed by trials. How we grade
On this page
What does alcohol do to sleep?
A 2013 review pulled together every known lab study of healthy people who drank before bed. At all doses, the pattern was the same:
- Falling asleep: faster.
- First half of the night: more consolidated, with more deep sleep in most studies.
- Second half of the night: more disrupted, with more waking, as the body clears the alcohol.
- REM sleep: the first dream period comes later, and at moderate and high doses there is less REM sleep over the night.
Because the studies are small but numerous and agree with each other, we grade the evidence strong.
Why does it backfire?
Alcohol is a sedative, which is why it makes you drowsy. But your body breaks it down at roughly one unit an hour, so after a few drinks it has worn off by the early hours. The brain then rebounds from the sedation. On top of that:
- alcohol is a diuretic, so you are more likely to wake needing the toilet,
- it relaxes throat muscles, making snoring and sleep apnoea worse,
- it can trigger reflux and night sweats.
Does drinking regularly change things?
The sleep-promoting effect of alcohol fades within a few nights of regular drinking, while the disruption tends to stay. People who drink heavily often have long-term insomnia, and sleep can remain poor for weeks or months after they stop.
How much is too much?
There is no precise safe amount for sleep. Lab studies find effects at doses equivalent to a couple of drinks, and they get bigger with more. Practical guidance:
- The NHS advises avoiding alcohol for at least 6 hours before bed.
- UK guidelines say to drink no more than 14 units a week, spread over three or more days, with some drink-free days. A pint of 4% beer is about 2.3 units; a 175 ml glass of 12% wine is 2.1.
- If you drink, have it with an early evening meal rather than late, and alternate with water.
What if you use alcohol to get to sleep?
It is common, and it is worth stopping. Using a nightcap regularly tends to make sleep worse over time, and the dose needed creeps up. If you can’t sleep without it, see insomnia and CBT for insomnia. If you are drinking heavily every day, don’t stop suddenly without advice: talk to your GP, because withdrawal can be dangerous.
Keep reading
- Screens, blue light and sleep: how much does your phone matter?
What studies show about phones, tablets, TV and blue light before bed, how big the effects are, and whether night mode or blue-blocking glasses help.
Weak - Exercise and sleep: does it help, and how late is too late?
What studies show about exercise and sleep quality, whether evening workouts keep you awake, and the best timing and type of activity for better sleep.
Moderate - The best bedroom temperature for sleep
How heat, cold and humidity affect sleep, what temperature to aim for in a UK bedroom, and how to sleep better in a heatwave.
Moderate
Common questions
Does a glass of wine help you sleep?
It may help you drop off, but it tends to make the second half of the night more broken. One small drink with an early dinner is unlikely to matter much; several drinks late in the evening usually will.
Why do I wake at 3am after drinking?
As your body clears the alcohol, its sedating effect wears off and there is a rebound: lighter sleep, more REM, more waking, plus a full bladder, dehydration and sometimes a racing heart. That usually lands in the early hours.
Does alcohol make snoring and sleep apnoea worse?
Yes. Alcohol relaxes the muscles of the throat, which makes snoring louder and can make breathing pauses in sleep apnoea longer and more frequent. The NHS advises people who snore to cut down on alcohol.
References
First published 4 November 2026. Spotted an error? Tell us and we'll correct it. Read our editorial policy.