Does alcohol affect sleep quality?
A depressant known to induce sleepiness and relaxation, alcohol has long been used as a ‘nightcap’ to promote sleep. And yet, despite its sedative effects, evidence has now linked alcohol – especially when consumed in excess – to poor sleep quality and quantity. Research also suggests alcohol use can increase the risk of sleep disorders, like insomnia and sleep apnoea.
Here, we outline how alcohol affects sleep quality and why we should avoid using it as a sleep aid.
What effect does alcohol consumption have on sleep quality and why?
Alcohol affects REM sleep
Sleep is regulated by cycles of activity in the brain, comprising two primary stages: non-rapid eye movement (NREM) and rapid eye movement (REM). The sleep cycle begins with NREM sleep followed by a short burst of REM sleep. You then get more REM sleep in each 90-minute sleep cycle, totalling four to five cycles for every eight hours of sleep.
While all stages of the sleep cycle are important for restoration, REM sleep – the principle stage in which dreaming happens – is particularly critical, serving as a vital form of emotional convalescence. During this stage of rest, processes affecting mood regulation, mental restoration, cognition, and memory occur throughout the body, acting as ‘overnight therapy’.
A review of 27 studies reported that alcohol negatively impacts REM sleep1. According to these findings, even though alcohol helped participants fall asleep faster and rest more deeply for a short period, it reduced overall REM sleep.
Failing to consistently achieve enough quality REM sleep can make you more emotionally reactive and lead to poor mental health outcomes, including increased anxiety, stress, and depression. This, in turn, may contribute to further sleep disruptions since mental ill health and sleep issues often have a bidirectional relationship.
Alcohol leads to frequent night-time arousals
In the first half of the night – as your body is metabolising alcohol – you’ll probably fall asleep quicker and spend more time in deep sleep (also known as stage three of NREM sleep). But this is offset by increased sleep disturbances in the second half of the night.
Once your liver enzymes fully metabolise the alcohol and any of its sedative effects wear off, your body will experience a ‘rebound effect’: you will transition from deeper to lighter sleep, with frequent awakenings and arousals2.
Although you may not remember rousing throughout the night, you will wake in the morning feeling tired, unfocused, and sluggish – characteristic symptoms of a ‘hangover’.
Alcohol suppresses melatonin
Drinking alcohol in the evening also adversely impacts your sleep hormone, melatonin, which governs your sleep-wake cycle. Evidence suggests drinking moderately up to an hour before bed can suppress melatonin production by nearly 20 per cent3.
Alcohol is a diuretic
During sleep, various biological processes – including those involved in your bladder – are put into ‘hibernation’ mode. But since alcohol is a diuretic – a substance that increases the passing of urine – it disrupts this practical system by making you need to use the bathroom more, which further disrupts sleep4.
Alcohol and insomnia
Insomnia is an extremely widespread sleep disorder in the UK. It’s characterised by a persistent difficulty falling asleep, maintaining sleep, or waking too early, despite having adequate opportunity to sleep.
Drinking alcohol and insomnia often co-exist. Because alcohol fragments sleep and reduces REM sleep, it can lead to insomnia symptoms and excessive sleepiness the next day. This, in turn, can trigger a negative feedback loop of self-medicating with caffeine and other stimulants to stay awake during the day, then consuming alcohol to offset any stimulating effects to fall asleep at night5.
Drinking excessively in one sitting – otherwise known as ‘binge drinking’ – can be especially adverse for sleep quality. People who binge drink – particularly adolescents and young adults – commonly experience increased trouble falling asleep and maintaining sleep6.
Moreover, individuals who drink regularly can also build up a dependency on alcohol, needing more to feel relaxed to initiate sleep. However, this exacerbates sleep problems and can lead to other long-term health issues.
Alcohol and sleep apnoea
Obstructive sleep apnoea is a sleep disorder in which breathing starts and stops during sleep. These pauses in breathing can cause sleep disruptions, resulting in excessive daytime tiredness and mood swings. Without treatment, it can lead to poor long-term health outcomes.
Alcohol and sleep apnoea have an interesting relationship, with studies suggesting alcohol consumption may increase the risk of developing this sleep disorder by 25 per cent7.
Not only does alcohol make your breathing slower and shallower, but it also relaxes the muscles in your throat, providing the ripe conditions for the upper airway to collapse. This often leads to snoring – due to the vibration of the soft tissues – or the complete obstruction that happens in sleep apnoea.
For those already with a sleep apnoea diagnosis, drinking alcohol can aggravate symptoms and worsen sleep quality.
How much alcohol does it take to affect sleep?
While heavy drinking can exacerbate the effects of alcohol on sleep, even regular, moderate drinking is enough to create sleep problems. Just one glass of alcohol in the evening can affect your sleep quality. Generally, if you’re going to bed feeling slightly inebriated, you’ve probably had too much to drink, and your sleep will be impaired.
To support sleep, try to drink moderately – no more than two drinks – a maximum of two to three times per week. And always make an effort to drink two glasses of water for every alcoholic beverage consumed. This will flush out the alcohol and promote better sleep quality.
When’s the best time to drink alcohol?
If you want to reduce the risk of sleep disruptions, the best time to metabolise alcohol is early to mid-evening, or traditional ‘happy hours’5. This is because it takes around an hour for the body to process each serving of alcohol.
Does alcohol help you sleep?
People have been using alcohol as a sleep aid for many years. And due to its sedative properties, it’s true that drinking alcohol often speeds up sleep onset and reduces the time it takes to fall asleep.
However, as soon as your body metabolises alcohol, its sedative effects fade, and you will likely experience disruptions later in the sleep cycle, even if you don’t recall waking up in the night.
How can I reduce my alcohol consumption?
Reducing your alcohol consumption is a sensible place to start if you want to prioritise your sleep quality.
Here are some of our tips to help moderate your intake:
Mix a glass of wine with mineral water
Mix beer with lemonade
Avoid situations where there’s pressure to drink in rounds
Let your family and friend know that you’re cutting down
Alternate an alcohol-free beverage with an alcoholic one
Use smaller glasses for your drinks
Have at least three drink-free days of the week
Drink plenty of water on the days you do drink
Most of us like to unwind with a drink now and again. But if you notice that alcohol – especially when consumed in excessive amounts – regularly affects your sleep quality and daytime functioning, you may need to rethink your consumption.
Want to learn more about how sleep affects our body and mind? Feel free to explore the rest of our sleep hub.
- Ebrahim. I., Shapiro. C., Williams. A. & Fenwick. P. (2013). Alcohol and Sleep I: Effects on Normal Sleep. Alcoholism: Clinical and Experimental Research. 37(4), 539`-549.
- Colrain. I.M., Nicholas. C.L. & Baker. F.C. (2014). Alcohol and the sleeping brain. Handbook of clinical neurology. 125, 415–431.
- Rupp. T., Acebo. C. & Carskadon. M. (2007). Evening Alcohol Suppresses Salivary Melatonin in Young Adults. Chronobiology International. 24(3), 463-470.
- Thakkar. M., Sharma. R. & Sahota. P. (2015). Alcohol disrupts sleep homeostasis. Alcohol. 49(4), 299-310.
- Colrain, I. M., Nicholas, C. L., & Baker, F. C. (2014). Alcohol and the sleeping brain. Handbook of clinical neurology, 125, 415–431.
- Popovici, I., & French, M. T. (2013). Binge drinking and sleep problems among young adults. Drug and alcohol dependence, 132(1-2), 207–215.
- Simou, E., Britton, J., & Leonardi-Bee, J. (2018). Alcohol and the risk of sleep apnoea: a systematic review and meta-analysis. Sleep medicine, 42, 38–46.
- Stein, M. D., & Friedmann, P. D. (2005). Disturbed sleep and its relationship to alcohol use. Substance abuse, 26(1), 1–13.
Olivia Salter has always been an avid health nut. After graduating from the University of Bristol, she began working for a nutritional consultancy where she discovered her passion for all things wellness-related. There, she executed much of the company’s content marketing strategy and found her niche in health writing, publishing articles in Women’s Health, Mind Body Green, Thrive and Psychologies.