Alcohol and Sleep: Could Drinking be Keeping You Awake at Night?

Posted by Dr Sophie Bostock - Sleep Expert on 12th Jun 2024

Alcohol and Sleep: Could Drinking be Keeping You Awake at Night?

Does alcohol actually help you sleep?

Many people drink alcohol before bed, believing that it will help them to wind down and fall asleep faster. While it’s true that alcohol has some relaxing properties, overall it interferes with good quality sleep. This means you’re more likely to wake up feeling groggy, tired and irritable.

Lack of good quality sleep can raise anxiety levels, and reduce self-control, which can make you more vulnerable to drinking excessively the following day.

In this article we explore the latest research into alcohol’s effects on sleep, and how – if you do decide to drink - you can minimise some of the negative effects.

How exactly does alcohol affect sleep quality?

Glasses of various coloured wines including red and white wines being poured.

Alcohol has multiple effects on our sleep architecture – our pattern of sleep. It can act as a sedative, helping us to fall asleep, and get into a deep sleep more quickly. However, in the second part of the night it makes sleep more fragmented and less restorative.

What is a ‘normal’ pattern of sleep, or sleep architecture?

On a typical night of sleep we cycle through 4 stages of sleep, perhaps 4 to 6 times. Many of us experience an occasional brief awakening between cycles.

Stages 1 to 3 are progressively deeper stages, and it becomes harder to wake someone up. Stage 3, or deep slow wave sleep, is the most physically restorative stage of sleep. This is when most of our growth hormone is produced, the immune system goes to work and we consolidate new memories.

After Stage 3, sleep gets lighter again, and we enter REM, or Rapid Eye Movement sleep, often associated with dreaming. REM sleep is very important for emotional regulation, creativity and problem-solving. We usually have more deep sleep in the first part of the night, and more REM sleep in the second part of the night.

How does alcohol affect our sleep cycles?

Under the influence of alcohol, we enter deep slow wave sleep more rapidly. However alcohol-induced deep sleep is not as restorative for the body; one study found that levels of growth hormone were 70-75% lower than during an alcohol-free sleep ( Prinz 1980 ).

In the second part of the night, alcohol suppresses REM sleep. We spend more time in the lighter, less restorative stages of sleep, and sleep is more fragmented with more brief wakings. Alcohol can also act as a diuretic, so we’re more likely to wake up to go to the toilet. There can be a REM ‘rebound’ effect before we wake up, where the brain tries to catch up on REM and we experience more intense, vivid dreams.

Why does alcohol affect sleep?

A group of friends raising their glasses of beer in a celebratory cheers.

Alcohol can impact on sleep on several ways. It has both stimulating and sedating effects, but overall it is a depressant; a substance which slows the nervous system ( Hendler 2013).

1. Alcohol as a stimulant

When we start drinking, alcohol stimulates the release of dopamine in the brain. This makes us feel more alert. Dopamine is sometimes called the ‘reward’ chemical, which makes us feel temporarily happier, and want to repeat a behaviour. Small amounts of alcohol also excite the nervous system; increasing heart rate and making us feel more energized. In some people this can lead to increased aggression, and impulsiveness.

Some people are more prone to the stimulating effects of alcohol, whereas others feel more sedating effects.

2. Alcohol as a sedative

The percentage of alcohol that reaches the bloodstream is known as the Blood Alcohol Concentration (BAC). When the levels of alcohol reach 80 mg/100 ml (~0.08% BAC) in the blood, which is the legal limit for driving in the UK, the effects of alcohol are mainly sedating – we feel less alert, our reaction times slow, we may feel depressed, our balance is off and our co-ordination is impaired ( Abrahao 2017).

The sedating impacts of alcohol can help us fall asleep, but they can also affect our breathing during sleep. Alcohol can promote relaxation of the muscles in the tongue and throat, making them more likely to collapse and narrow during sleep. It also causes changes to blood vessels in the nose, leading to greater airway resistance in the nasal passages. These changes increase the risks of snoring, and the temporary pauses in breathing which characterise the condition of  sleep apnoea.

3. Alcohol disrupts circadian rhythms

Alcohol can also have a disruptive effect on our body clocks, or circadian rhythms. This usually means a delay in our internal rhythms so that we stay awake for longer, and are more likely to struggle to wake up early in the morning. A recent UK study reported that even low levels of alcohol consumption can increase the risk of snoring and having a night owl chronotype ( Zheng 2024).

4. Longer term impacts of alcohol misuse

Heavy drinking and alcohol use disorders are associated with high rates of severe insomnia, excessive daytime sleepiness and frequent night-time wakings. Chronic alcohol consumption can lead to tolerance to the effects of alcohol, so that drinkers may need to drink more to help them get to sleep; perpetuating a harmful cycle that makes them tired during the day and reduces self-control.

Withdrawal from alcohol can also lead to sleep disruption. Poor sleep is a risk factor for relapse in those recovering from alcohol misuse ( Thakkar 2015), so it’s important to focus on sleep improvement, alongside treatment for addiction.

How much alcohol do you need to drink for it to interfere with sleep?

Infographic chart displaying how long it takes for our body to process alcohol be it 3 pints of beer or 6 single measurements of spirits.

The rate at which alcohol is absorbed into the bloodstream and then metabolised by the liver varies a lot between individuals. On an empty stomach, blood alcohol concentration peaks about one hour after your drink, depending on the amount drunk; it then declines in a more or less linear way for the next four hours.

On average it takes one hour for the liver to process one unit of alcohol (equivalent to half a pint of 3% beer; a single shot of 40% spirit or half a medium glass of wine). However, blood alcohol concentration varies according to sex, genetics, size and body build, phase of the menstrual cycle (it is higher premenstrually and at ovulation), previous exposure to alcohol, type of drink, and whether alcohol is taken with food or drugs.

Some studies have detected no impacts on sleep after a single drink (BAC 0.03%), but negative impacts of alcohol seem to be reported consistently with a BAC of 0.08% or above – which is the legal limit for driving ( Feige 2006, McCullar 2024).

Alcohol is removed from the blood at a rate of about 3.3 mmol/hour (15 mg/100 ml/hour), but this varies in different people, on different drinking occasions, and with the amount of alcohol drunk.

Can you reduce the effects of alcohol on sleep?

A person refusing another drink as they can already tell they've had enough alcohol.

To minimise the effects of alcohol on sleep, you could abstain entirely, or limit yourself to one drink and stop drinking at least two hours before getting into bed. In general, the more alcohol your drink and the closer you drink it to bedtime, the stronger its effects will be.

If you’re anticipating drinking a little more, you might also consider:

  • Be well rested to help compensate for any sleep disruption
  • Drink slowly to reduce the rate of increase in BAC
  • Eat a meal before drinking, and snack regularly - having food in the stomach can dilute the alcohol and slow the emptying of the stomach into the small intestine, where alcohol is rapidly absorbed. Peak BAC could be as much as 3 times higher in someone with an empty stomach than in someone who has consumed food before drinking.
  • Stay well hydrated – try alternating sips of alcohol with water.
  • Avoid medication which can intensify the effects of alcohol. This can include some anti-anxiety drugs, ADHD medication, cough and cold medicines and some diabetes medications – always read the label.

How do you know whether alcohol is interfering with your sleep?

One of the best ways to become more aware of the factors influencing your sleep is to keep a sleep journal for a few weeks. If you also track your drinks, you will hopefully be able to spot patterns based on what you’re drinking, and when. If you drink frequently, you might find that you sleep worse when you stop drinking. This could be a withdrawal effect, which suggests your body may have become dependent on alcohol.

How do you know if you’re drinking too much?

If you’re concerned about your drinking, or you’d like help to cut down, speak to your GP for advice. They may ask you the following questions:

  1. Have you ever felt you needed to Cut down on your drinking?
  2. Have people Annoyed you by criticizing your drinking?
  3. Have you ever felt Guilty about drinking?
  4. Have you ever felt you needed a drink first thing in the morning ( Eye-opener) to steady your nerves or to get rid of a hangover?

These 4 questions are called the CAGE questionnaire ( Ewing 1994). If you answer ‘Yes’ to two or more questions, this suggests that you are at high risk of having an alcohol disorder, and you may benefit from some professional help to cut down. Your GP may suggest different types of assessment, counselling and support options, such as from local community alcohol services.

Drinkline is the national alcohol helpline. If you're worried about your own or someone else's drinking, you can call this free helpline in complete confidence. Call 0300 123 1110 (weekdays 9am to 8pm, weekends 11am to 4pm).

authors profile
Dr Sophie Bostock
Sleep Expert
Sophie brings a wealth of expertise to the role having spent the last six years researching and championing the importance of sleep science in NHS and corporate settings. Sophie was responsible for improving access to the award-winning digital sleep improvement programme, Sleepio, as an NHS Innovation Accelerator Fellow. She has delivered hundreds of talks, including for TEDx and Talks@Google, and regularly features as a media sleep expert.
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