How Does Alcohol Affect sleep?

Many people believe that having a couple of drinks improves sleep. The result may be just the opposite – read on and find out more.

Many people drink alcohol after a long tiresome day. It can help to fall asleep and release tension, but does it help in the long term?

True, a couple of drinks may help you drift off, but the quality of sleep may be bad. When you have more than 14 drinks a week, you are risking to wake up exhausted.

How Alcohol Acts Once It’s In The Body?

alcohol activity while sleeping

The reason alcohol is bad for your sleep lies in its formula and general effect. It is a central nervous system depressant, which means that it slows down brain activity. That's why it has a sedative effect which causes sleepiness and relaxation. Sounds good for sleep, but is it? After a person drinks alcohol, it absorbs into the bloodstream from the stomach. Liver enzymes metabolize the substance, but this process is slow. Alcohol continues to circulate in the body, so the liver continues to metabolize alcohol at night time. This situation causes disruptions in sleep and makes it's quality lower.

Alcohol Disrupts Sleep Patterns

alcohol is bad for sleep patterns

Why exactly is alcohol bad for sleep patterns? To understand this, we need to understand sleep cycles. Usually, a sleep cycle consists of four stages:

Stage 1: Non-Rapid Eye Movement (NREM)

sleep cycle consists of four stages

There are three stages of NREM. In the first one, a person transits from wake to sleep. The body begins to relax and shut down. Breathing, heartbeat, and eye movements slow down. Muscles relax, and activity of the brain is decreasing. It is called “the light sleep.” Alcohol encourages this stage of sleep as it helps to relax.

Stage 2 of NREM

Brain activity, heartbeat, and breathing become slower. Body temperature and eye movement decrease. The organism is preparing for deeper sleep, so it's the longest stage.

Stage 3 of NREM

All body activity continues to slow down. Breathing, heartbeat, and brain activity reach their lowest levels. That’s why this stage is called “slow-wave sleep.” Alcohol decreases this stage, so the sleep may become shallow.

Stage 4: Rapid Eye Movement (REM)

REM starts 90 minutes after the person falls asleep. The eye movement begins again, and dreaming takes place. The breathing rate and heartbeat also become quicker. This stage is vital, as it helps memory consolidation.


Throughout the night, these stages repeat like cycles which last 90-120 minutes. Every night, there are four or five cycles.

Alcohol Changes Sleep Stages Duration

During the first cycles, REM is pretty short, about 10 minutes. However, in the second part of the night, REM gets longer, up to 40 minutes; NREM time decreases. Alcohol disrupts this cycle and makes NREM shorter, which makes sleep quality low.

Sleep Stages Changes Duration with alcohol

Alcohol may help to fall asleep quickly and sleep deeply for some time. Then, it reduces rapid eye movement sleep, because it breaks the length of cycles. REM is restorative to the whole body, so the lack of this stage leads to problems during the daytime. The more drinks a person has, the worse is rapid eye movement sleep. The next day, people may feel drowsy, tired, and lacking concentration.

Apnea and Dehydration Prevent Deep Sleep

Sleep cycles aren’t the only things that suffer from alcohol intake. It is also known to cause snoring, apnea, dehydration, and tiredness.

Apnea is Common After Drinking

Sleep Apnea After Drinking

Alcohol may suppress breathing and cause sleep apnea along with pauses in breathing. Drinking can relax the muscles, so tissues in the throat, nose, and mouth prevent the air from flowing smoothly. This area vibrates, which causes apnea that may be strong enough to wake you up. Loud snoring is also common after alcohol intake.

Drinking Causes Dehydration

Dehydration with alcohol

Drinking is known to cause dehydration, so after drinking it you may wake up in the middle of the night to visit the toilet. Alcohol is a diuretic. That means it can draw water from the organism and cause cell dehydration, which leads to general tiredness.

Alcohol Causes Insomnia

Insomnia while drinking

Often, alcohol is used as a sleep aid when the person has insomnia. It may help fall asleep quickly, so a person may end up having alcohol dependence. Binge-drinking can further lead to even worse problems with sleep. Taking large amounts of alcohol in a short time raises the alcohol level in the blood to 0,08% or higher. This is bad for sleep quality and may lead to trouble falling asleep. Both men and women who binge-drink have difficulties staying asleep. All age groups, from adolescents to older adults, experience these effects.

As a result, alcohol abuse may lead to chronic problems. Michael Breus, Ph.D. and a sleep specialist, states that people who use alcohol to fall asleep are more likely to sleep talk, sleepwalk, and have memory problems.

So, When to Drink Alcohol, and How Much?

Drink Alcohol timings

Sure, the evening is nearly the best time to have a couple of drinks. Still, if you want to have a good night’s sleep, try to avoid drinking close to bedtime. The body needs to process the alcohol before you start to nod off. Usually, one hour is enough to process one unit, but knowing your body is also important. For different people, it may vary greatly.

Low, Moderate, and High Alcohol Consumption

Alcohol Consumption limit

Of course, light alcohol consumption is less harmful. Still, this depends on the person. Here are the general statistics:

Amount of Alcohol How Many Drinks Per Day Effect on Sleep
Low Less than 2 servings for men, less than 1 serving for women 9.3% worsening in sleep quality
Moderate 2 servings for men

1 serving for women

24% decrease in sleep quality
High More than 2 servings for men, more than 1 serving for women 39.2% worse sleep

Take into account that servings differ for various types of alcohol. One serving is:

  • 12 ounces of beer which has 5% alcohol
  • 5 ounces of wine which has 12% of alcohol
  • 1 ounce of spirits or liquor with 40% of alcohol

When drinking, try to keep in mind the amount if you want to sleep better and minimize harmful effects.

7 Tips for Better Sleep

There are better ways to fall asleep than drinking alcohol. Try to develop positive sleep habits, such as ones below:

  1. Exercise regularly, but not close to bedtime. Otherwise, hormones in your body won’t let you fall asleep easily.
  2. Do not take caffeine or alcohol in the evening. Avoiding nicotine is also a good idea.
  3. Try drinking a cup of hot milk or herbal tea close to bedtime.
  4. Before sleep, make a to-do list for tomorrow to reduce anxiety.
  5. Keep the bedroom cool.
  6. Use the bed only for sleeping. This way, you build a strong association between bed and sleep.
  7. Go to bed at the same time. Waking up at a certain hour is also good for the body.

FAQ About Alcohol & Sleep

When to stop drinking if I want to sleep properly?

Stop drinking alcohol four or more hours before going to bed. This is guaranteed to help you sleep.

What is moderate and heavy drinking?

Moderate drinking is generally 2 drinks per day for men or 1 drink a day for women. Heavy drinking is 15 drinks during a week for men and more than 8 drinks for women.

Does alcohol have a different effect on men and women’s sleep?

Women show signs of intoxication earlier because they usually weigh less and have lower amounts of water in the body. That’s why the same amount of alcohol affects men and women differently.


Alcohol is a sedative, so it relaxes us and helps us fall asleep quicker. But its later effect on sleep is not positive. It disrupts the sleep stages and changes their balance. Rapid eye movement sleep stage becomes overall shorter, which means that the body rests less. That is why people are often tired, drowsy, and sleepy the next day after drinking.

Also, alcohol leads to apnea, dehydration, and severe insomnia in heavy drinkers. The same amounts of alcohol affect men and women differently, so the quantity of servings varies for them. People have different body mass and metabolism, so knowing your norm is important.

Generally, experts advise not to overuse alcohol and take only low amounts of alcohol. Do not drink 4 hours before sleep. If you want to improve sleep, exercise daily, reserve bed only for sleeping, keep the bedroom cool, and follow a daily sleep regime.

What can you drink instead of alcohol before bed to help you fall asleep faster? The answer is milk, click here to learn more.

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