Why alcohol and sleep don’t mix: Everything you need to know
Think a nightcap can help you get a better night’s sleep? Think again. Alcohol may be known as a sedative which can help induce feelings of relaxation and sleepiness, but this doesn’t mean it will give you a good night’s sleep. Here, we explain why alcohol and sleep don’t mix.
Does alcohol help you sleep?
This isn’t a simple answer and can be presented as a double-edged sword. On one side, alcohol does have sedative properties that help you fall asleep faster1. Despite this, alcohol can also affect the quality of sleep you get often leading to daytime sleepiness.1
To understand how alcohol impacts sleep quality, it’s important to understand what a normal sleep pattern looks like and why each stage has important functions in sleep health, physical health, and mental health.1
What does a normal sleep pattern look like?
A normal sleep pattern consists of two different ‘sleep states’ each with their own important functions: 2, 3
- NREM – Non-Rapid Eye Movement – important for memory consolidation, brain plasticity, cardioprotective functions, and overall health. 3
- REM – Rapid Eye Movement – important for sensory processing, memory, and cognition.3
Normal, healthy sleep follows a cyclical pattern through four different stages of sleep:
- Stage 1: NREM1 – When in this stage you are moving from consciousness to a light sleep. Your eyes and muscles will relax, and your heart rate, breathing and brain activity start to slow down.3
- Stage 2: NREM2 – Your heart rate and breathing continue to slow down, your body temperature decreases, and your muscles relax more. 3
- Stage 3: NREM3 – You are now in what is also known as deep sleep (or slow wave sleep -SWS). Your heart rate and breathing drop to their lowest levels which is important for protecting your heart health. In fact, a lack of deep sleep has been associated with an increased risk of high blood pressure, heart attack, and stroke. 2,3
- Stage 4: REM – As the name suggests, during this stage of sleep your eyes move rapidly, and you may experience dreams. To stop you from acting out your dreams your arm and leg muscles become temporarily paralysed. This is also the stage of sleep when your brain starts important functions associated with memory. 2,3
Each sleep cycle last roughly 90-120 minutes, which amounts to four to five cycle for every eight hours of sleep. 2,3
So, if this is what a normal sleep pattern looks like, how is the pattern affected by alcohol and why does it matter?
How does alcohol affect sleep?
Drinking alcohol may help you get to sleep a little faster but it affects the amount of REM sleep you could be getting.1 Alcohol has been shown to impact the normal sleep pattern by creating an imbalance between deep sleep and REM sleep, resulting in more deep sleep and less REM. 1
You may be thinking that more deep sleep is good for you, and there is no doubt deep sleep is good for your physical and mental health; however, sleep is all about balance and this imbalance can decrease your overall sleep quality, which results in shorter sleep duration and more sleep disruptions. 1
Why does it matter if your sleep is out of sync?
Your sleep is governed by a master biological clock (body clock), but this clock also has an important role in regulating nearly all your body’s systems, from metabolism and immunity to energy, sleep, sexual drive, cognitive functions and mood.4
So, when you drink alcohol it disrupts your body’s natural rhythms, directly interfering with your body clock’s ability to synchronize itself which can wreak havoc on your sleep and other body systems.4 Research has shown that alcohol creates a disruption that not only affects your normal sleep pattern, but it is also linked to conditions such as poor liver function, leaky gut syndrome, and depression.4
Alcohol and insomnia
As alcohol is known for its sedating (sleep inducing) properties, you may assume it can be used as a sleep aid for insomnia. However, insomnia is not just a condition defined by the inability to get to sleep; insomnia can also be defined by the inability to stay asleep and/or waking up still feeling exhausted due to poor quality to sleep.1
Here we are met with our double-edged sword again. Alcohol may help those with insomnia get to sleep a little faster, but the reduction in REM from alcohol consumption affects the quality of sleep which ultimately results in excessive daytime sleepiness and other negative consequences such as poor concentration, low mood, low energy, impaired memory, and even an increased risk of car accidents.1,5
Alcohol and Obstructive Sleep Apnoea
Did you know that alcohol’s sedative effects extends to your entire body, including your muscles?6 The idea of relaxed muscles may sound like it will help you sleep better, but not if those relaxed muscles are in your airway. 6 Drinking moderate to high amounts of alcohol causes the muscles in your throat to relax, which narrows your airway resulting in episodes of sleep apnoea.7,8
Sleep apnoea is when your breathing stops and starts while you sleep. The most common type is called Obstructive Sleep Apnoea (OSA).8 Even consuming just one serving of alcohol before bed can lead to Obstructive Sleep Apnoea and heavy snoring, even for people who have not previously been diagnosed with sleep apnoea.1
Research has linked the combination of sleep apnoea, snoring, and alcohol consumption with an increased risk of heart attack, arrhythmia (irregular heartbeat), stroke, and sudden death.7
Other sleep problems caused by alcohol
Nocturia – A condition in which you wake up during the night because you have to urinate – Alcohol is a diuretic so you will likely wake in the night needing the loo which affects the quantity and quality of your sleep.
Nightmares and vivid dreams – With alcohol in your system, you are more likely to have intense, colourful dreams or nightmares6. Did you know that nightmares have been shown to contribute to a negative mood, non-restorative sleep, and tiredness during the day?9
Sleepwalking and other parasomnias – parasomnias are sleep disorders that causes abnormal behaviour while sleeping, such as sleepwalking, sleep talking, sleep eating, sleep paralysis and bedwetting. Alcohol has been shown to increase the risk for parasomnias.4
How much alcohol does it take to affect sleep quality?
Even low amounts of alcohol have been shown to reduce sleep quality.1
One 2018 study10 compared sleep quality among subjects who consumed different amounts of alcohol and concluded the following:
- Low amounts of alcohol (fewer than two servings per day for men or one serving per day for women) decreased sleep quality by 9.3%.
- Moderate amounts of alcohol (two servings per day for men or one serving per day for women) decreased sleep quality by 24%.
- High amounts of alcohol (more than two servings per day for men or one serving per day for women) decreased sleep quality by 39.2%.
The findings of the study above demonstrate that the more alcohol you consume the more likely it will impact your quality of sleep.10
When should you stop drinking to help minimise sleep disruption?
Drinking alcohol up to six hours before bed can cause sleep disruptions.11 There is a relatively long-lasting effect on the brain with alcohol use, so avoiding alcohol at night is the best way to avoid sleep disruptions.11
Say no to the nightcap
There are many negative consequences associated with alcohol such as high blood pressure, liver disease and even cancer, and now you know that alcohol and a good night’s sleep don’t mix.12,13 The more you drink, the more likely your sleep quality will be impacted,10 and your sleep also has an important role in your physical and mental health. So, when possible, say no to the nightcap and say hello to a better night’s sleep.
A note on alcohol and sleep aids
While we’re on the topic of alcohol, it’s important to remember that it is recommended to never combine alcohol with sleep aids as their interaction can cause serious side effects.
- Sleep foundation – alcohol and sleep
- Sleep: A Health Imperative. Sleep, Volume 35, Issue 6, 1 June 2012, Pages 727–734
- Functions and mechanisms of sleep
- Psychology Today – alcohol and sleep what you need to know
- NICE – insomnia
- Cleveland Clinic – why you should limit alcohol before bed for better sleep
- Very well Mind – alcohol and sleep
- NHS – sleep apnoea
- Paul, Franc et al. “Nightmares affect the experience of sleep quality but not sleep architecture: an ambulatory polysomnographic study.” Borderline personality disorder and emotion dysregulation vol. 2 3. 13 Feb. 2015,
- Pietilä, J., Helander, E., Korhonen, I., Myllymäki, T., Kujala, U., & Lindholm, H. (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.
- Stein, M. D., & Friedmann, P. D. (2005). Disturbed sleep and its relationship to alcohol use. Substance abuse, 26(1), 1–13.
- NHS – alcohol misuse
- Medical News Today – How does alcohol affect your sleep