Alcohol and sleep: why a nightcap keeps you from resting well

Updated November 14, 2026 Six Habits Editorial Team

A man lying awake in the middle of the night, an empty wine glass on the nightstand

The short answerAlcohol helps you fall asleep faster but worsens the second half of the night: sleep becomes fragmented and REM sleep is suppressed. In a large study, even a small amount of alcohol reduced the body’s physiological recovery in the first hours of sleep, and larger amounts reduced it much more.

Key points

Alcohol shortens the time to fall asleep but disrupts sleep later in the night.
It suppresses REM sleep, which matters for memory and emotions.
Overnight physiological recovery dropped by about 9% with a low dose, 24% with a moderate dose and 39% with a high dose.
Alcohol worsens snoring and sleep apnea.

The “nightcap” myth

Many people use a drink to relax and fall asleep. Alcohol is a sedative, so it does make it easier to drift off, but the rest of the night pays the price.

What the research shows

Sleep architecture. A review of 27 studies found that alcohol at all doses shortened the time to fall asleep and deepened sleep in the first half of the night, but disrupted the second half and suppressed REM sleep, especially at higher doses (Ebrahim et al., 2013).

Overnight recovery. In a Finnish study of more than 4,000 people wearing heart rate monitors, alcohol lowered physiological recovery (heart rate variability) during the first 3 hours of sleep by about 9% at low doses, 24% at moderate doses and 39% at high doses (Pietilä et al., 2018).

Other effects

Alcohol relaxes throat muscles, worsening snoring and sleep apnea.
It increases trips to the bathroom at night.
Regular drinking to fall asleep can lead to tolerance and dependence.

What to do instead

Sleep hygiene research supports avoiding alcohol close to bedtime as part of good sleep habits (Irish et al., 2015). Instead, try:

a nonalcoholic evening ritual: herbal tea, a warm shower, reading;
relaxation or slow breathing;
a consistent bedtime and wake time.

Frequently asked questions

Does a single glass of wine affect sleep?

In the Finnish study, even a low dose reduced recovery measured by heart rate variability, although the effect was smaller than with more drinks.

How long before bed should I stop drinking?

Effects depend on the amount. Many sleep experts suggest finishing alcohol at least 3 to 4 hours before bed, and less is better.

Sources

Ebrahim et al. (2013). Alcohol and Sleep I: Effects on Normal Sleep. Alcoholism: Clinical and Experimental Research 37(4). doi:10.1111/acer.12006
Pietilä et al. (2018). Acute Effect of Alcohol Intake on Cardiovascular Autonomic Regulation During the First Hours of Sleep in a Large Real-World Sample of Finnish Employees: Observational Study. JMIR Mental Health 5(1):e23. doi:10.2196/mental.9519
Irish et al. (2015). The role of sleep hygiene in promoting public health: A review of empirical evidence. Sleep Medicine Reviews 22:23-36. doi:10.1016/j.smrv.2014.10.001

Prepared according to our evidence methodology and the principles of lifestyle medicine. For education only; it does not replace advice from your doctor.

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Alcohol and sleep: why a nightcap keeps you from resting well

Key points

The “nightcap” myth

What the research shows

Other effects

What to do instead

Frequently asked questions

Sources

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