What one glass of wine does to your night

Start with the part everyone notices, the drowsiness, and then the part most people miss: what happens in the early hours, and how little it takes.

Alcohol helps you drop off, then turns on you#

At every dose studied, alcohol shortens the time it takes to fall asleep and steadies the first half of the night, then disrupts the second half.¹ Tolerance to its drowsy effect also builds quickly.⁶

A review of the laboratory studies in healthy volunteers found the same pattern across doses: falling asleep faster, a more consolidated first half of the night with more deep sleep, then more disrupted sleep in the second half.¹

That early drowsiness is why many people use a glass to wind down. Yet people rapidly develop tolerance to alcohol's sedative effect,⁶ so a nightcap that helped at first tends to help less over time.

• One glass helps me unwind
• I always wake at 3 after wine
• I sleep like a log, then I'm wide awake
• My tracker shows a high heart rate after drinks
• I wake up hot and thirsty
• Groggy even after eight hours

The second half of the night pays for the first#

Alcohol's effect flips during the night: the first half of sleep is consolidated, then sleep becomes more disrupted in the second half, and the first period of dream (REM) sleep is pushed back at every dose.¹

The delayed first REM period is the most recognisable effect of alcohol on dream sleep, followed by a reduction in total REM sleep at moderate and high doses.¹ In everyday life, this second half is often the part you notice: waking in the early hours, then lighter sleep until the alarm.

How much does it take? Less than many people assume.

Two drinks are enough to disturb dream sleep#

A meta-analysis of 27 studies found dream (REM) sleep disrupted after a low dose of up to about two standard drinks, and the disruption grew as the dose rose.²

For a 70 kg person, 0.5 g per kilogram is 35 g of pure alcohol. Standard drink sizes differ between countries, so treat the drink counts as rough guides. The meta-analysis could not pin down the effect on total sleep time, sleep efficiency or time awake in the night, because the results were too uncertain.²

Sleep stages are only half the story. While you sleep, alcohol also changes what your heart and your breathing do, and a nightly habit changes things again.

Your heart works harder through the night#

During sleep after alcohol, the nervous system shifts towards its alert side: heart rate rises and heart rate variability falls.⁴ In more than 4,000 Finnish employees, even low amounts reduced overnight recovery.³

In a laboratory study, 26 healthy adults aged 30 to 60 had a placebo, a low dose or a high dose before bed: one standard drink for women and two for men, or three and four. Alcohol raised their heart rate through the night and suppressed heart rate variability, with larger effects at the higher dose.⁴

A real-world study followed 4,098 Finnish employees wearing heart monitors on days with and without alcohol. Recovery in the first three hours of sleep fell by about 9, 24 and 39 percentage points after low, moderate and high intake, and being physically active did not protect against it. Some of the authors worked for companies developing heart rate monitoring.³

Drinking is linked to more sleep apnoea#

In a meta-analysis of 21 studies, higher alcohol consumption went with a 25% higher risk of sleep apnoea.⁷ Loud snoring, or pauses in breathing that someone has noticed, are a reason to see your doctor.

The studies were observational and varied a lot, and the authors found signs of publication bias, so the exact size of the link is uncertain. They still conclude that reducing alcohol is of potential value in preventing and treating sleep apnoea.⁷

And if a drink has become your way of getting to sleep every night, a different problem builds.

A nightly nightcap stops working#

Tolerance to alcohol's sedative effect develops rapidly, so a nightcap tends to do less over time.⁶ For insomnia that has lasted months, the recommended first treatment is cognitive behavioural therapy for insomnia (CBT-I).⁹

Alcohol also combines badly with tiredness: together with short or lost sleep, it made daytime sleepiness worse and deepened its own effect on performance.⁶ For chronic insomnia, the American Academy of Sleep Medicine strongly recommends CBT-I, a structured programme that retrains sleep habits and thoughts about sleep.⁹

Alcohol and sleeping tablets or other sedating medicines are a risky mix. The Swiss federal commission on addiction says it is safest not to drink at all when you take medicines that interact with alcohol.⁵ Ask your doctor or pharmacist about yours.

With the effects in view, the practical questions: what Swiss experts now advise, whether timing helps, and how to see the effect on your own sleep.

Swiss experts now say less is better#

In March 2026 the Swiss federal commission on addiction withdrew the low-risk limits it had published in 2018, noting that even one standard glass a day raises the risk of certain cancers. Its position is now simply that less is better.⁵

The 2018 guidance allowed up to five standard glasses a week for women and ten for men. The commission now says those values are no longer valid, that one standard glass a day increases the risk of cancers of the mouth and throat, larynx, oesophagus, breast, liver and bowel, and that the idea of a glass of wine being good for the heart rested on methodologically questionable studies.⁵

The commission also notes that people who cut down or stop usually report benefits quickly, including better sleep and more energy.⁵ Those are people's own reports rather than trial results, but they fit what the sleep research shows about the second half of the night.¹²

The amount matters more than the clock#

A 2025 meta-analysis set out to study both the dose and the timing of alcohol, and its summary reports clear findings on dose but no recommended gap before bed.² The amount you drink is what the evidence speaks to most clearly.

That does not make timing irrelevant; it means the research has not settled it. A glass with an early dinner, a smaller glass, or alcohol-free weeknights are all reasonable things to try, and your own nights will tell you which of them makes a difference.

An alcohol-free fortnight shows you the difference#

Compare a usual week with an alcohol-free one, keeping bedtimes and everything else steady. Note how rested you feel and, if you wear a tracker, your night-time heart rate, which researchers suggest can show alcohol's effect on an individual.³

Change only the alcohol during the test, so the comparison means something. A single good or bad night tells you little; two weeks side by side tell you far more.

For most people this is a habit worth testing. For some, alcohol and sleep need a doctor first, and this last part explains where our work sits alongside theirs.

Some signs need a doctor before any test#

Needing a drink to sleep most nights, morning shakes, sweats or anxiety that settle with a drink, loud snoring with pauses in breathing, or months of poor sleep call for a doctor. If you drink heavily every day, do not stop suddenly on your own.⁸

In people who are dependent on alcohol, a sudden reduction can bring on severe withdrawal, and UK guidelines recommend medically assisted withdrawal, in hospital for those at high risk.⁸ Milder withdrawal signs include anxiety after waking, sweating, mild tremors and nausea or retching in the morning.¹⁰ Speaking to your doctor first is the safe way to start.

If you would rather talk to someone anonymously first, SafeZone.ch offers free, anonymous online counselling on alcohol and other addiction questions in Switzerland.¹¹

We look at what the glass is doing for you#

Our part sits alongside medical care, never instead of it. We help you look at your evenings, sleep, stress, meals and movement over two weeks, and find what the glass is doing for you and what could do it instead.

In our coaching, the evening glass usually has a job: marking the end of the working day, easing stress, making dinner feel like an occasion. Taking it away without replacing that job rarely lasts, so we look for another way to switch off that suits you.

Our programmes and app set your own sleep data against what you did, ate and drank, so you can see the pattern for yourself. If you would like to look at yours, talk it through with our care team on a free call. It is a coaching conversation, not a medical consultation, and when something points to a doctor, we will tell you so.