Alcohol is a central nervous system depressant that causes brain activity to slow down. Alcohol has sedative effects that can induce feelings of relaxation and sleepiness, but the consumption of alcohol — especially in excess — has been linked to poor sleep quality and duration. People with alcohol use disorders commonly experience insomnia symptoms. Studies have shown that alcohol use can exacerbate the symptoms of sleep apnea.
Drinking alcohol in moderation is generally considered safe but every individual reacts differently to alcohol. As a result, alcohol’s impact on sleep largely depends on the individual.
How Does Alcohol Affect Sleep?
The relationship between alcohol and sleep has been studied since the 1930s, yet many aspects of this relationship are still unknown. One 2018 study compared sleep quality among subjects who consumed various amounts of alcohol:
- Low amounts of alcohol: Having fewer than two servings of alcohol per day for men or one serving per day for women decreased sleep quality by 9.3%.
- Moderate amounts of alcohol: Having two servings of alcohol per day for men or one serving per day for women decreased sleep quality by 24%.
- High amounts of alcohol: Having more than two servings of alcohol per day for men or one serving per day for women decreased sleep quality by 39.2%.
After a person consumes alcohol, the substance is absorbed into their bloodstream from the stomach and small intestine. Enzymes in the liver eventually metabolize the alcohol, but because this is a fairly slow process, excess alcohol will continue to circulate through the body. The effects of alcohol largely depend important factors like the amount of alcohol and how quickly it is consumed, as well as the person’s age and body composition.
To understand how alcohol impacts sleep, it is important to understand the different stages of the human sleep cycle. A normal sleep cycle consists of four different stages. The fourth stage, REM sleep, begins about 90 minutes after the individual initially falls asleep. Eye movements will restart and the sleeper’s breathing rate and heartbeat will quicken. Dreaming primarily takes place during REM sleep. This stage is also thought to play a role in memory consolidation .
Drinking alcohol before bed can increase the suppression of REM sleep during the first two cycles. Since alcohol is a sedative, sleep onset is often shorter for drinkers and some fall into deep sleep rather quickly. As the night progresses, this can create an imbalance between slow-wave sleep and REM sleep, resulting in less of the latter and more of the former. This imbalance decreases overall sleep quality, which can result in shorter sleep duration and more sleep disruptions.
Alcohol and Insomnia
Insomnia, the most common sleep disorder, is marked by periods of difficulty falling or staying asleep. Insomnia occurs despite the opportunity and desire to sleep, and leads to excessive daytime sleepiness and other negative effects.
Since alcohol can reduce REM sleep and cause sleep disruptions, people who drink before bed often experience insomnia symptoms and feel excessively sleepy the following day. This can lead them into a vicious cycle that consists of self-medicating with alcohol in order to fall asleep, consuming caffeine and other stimulants during the day to stay awake, and then using alcohol as a sedative to offset the effects of these stimulants.
Binge-drinking – consuming an excessive amount of alcohol in a short period of time that results in a blood alcohol level of 0.08% or higher – can be particularly detrimental to sleep quality. In recent studies, people who took part in binge-drinking on a weekly basis were significantly more likely to have trouble falling and staying asleep. These findings were true for both men and women. Similar trends were observed in adolescents and young adults , as well as middle-aged and older adults .
Researchers have noted a link between long-term alcohol abuse and chronic sleep problems. People can develop a tolerance for alcohol rather quickly, leading them to drink more before bed in order to initiate sleep. Those who have been diagnosed with alcohol use disorders frequently report insomnia symptoms.
Alcohol and Sleep Apnea
Sleep apnea is a disorder characterized by abnormal breathing and temporary loss of breath during sleep. These lapses in breathing can in turn cause sleep disruptions and decrease sleep quality. Obstructive sleep apnea (OSA) occurs due to physical blockages in the back of the throat, while central sleep apnea (CSA) occurs because the brain cannot properly signal the muscles that control breathing.
During apnea-related breathing episodes – which can occur throughout the night – the sleeper may make choking noises. People with sleep apnea are also prone to loud, disruptive snoring. Some studies suggest that alcohol contributes to sleep apnea because it causes the throat muscles to relax, which in turn creates more resistance during breathing. This can exacerbate OSA symptoms and lead to disruptive breathing episodes, as well as heavier snoring. Additionally, consuming just one serving of alcohol before bed can lead to symptoms of OSA and heavy snoring, even for people who have not been diagnosed with sleep apnea.
The relationship between sleep apnea and alcohol has been researched fairly extensively. The general consensus based on various studies is that consuming alcohol increases the risk of sleep apnea by 25%.
Frequently Asked Questions About Alcohol and Sleep
Alcohol may aid with sleep onset due to its sedative properties, allowing you to fall asleep more quickly. However, people who drink before bed often experience disruptions later in their sleep cycle as liver enzymes metabolize alcohol. This can lead to excessive daytime sleepiness and other issues the following day. Drinking to fall asleep can build a tolerance, forcing you to consume more alcohol each successive night in order to experience the sedative effects.
Drinking to excess will typically have a more negative impact on sleep than light or moderate alcohol consumption. Research has shown that those who drink large amounts of alcohol before bed are more likely to take less time to fall asleep, but are also more likely to experience sleep disruptions and decreases in sleep quality. However, since the effects of alcohol are different from person to person, even small amounts of alcohol can reduce sleep quality for some people.
You can manage the negative effects of alcohol on sleep by giving your body ample time to metabolize alcohol before falling asleep. To reduce the risk of sleep disruptions, you should stop drinking alcohol at least four hours before bedtime.
Medical Disclaimer: The content on this page should not be taken as medical advice or used as a recommendation for any specific treatment or medication. Always consult your doctor before taking a new medication or changing your current treatment.
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Listed news articles do not represent the opinion of Sleep Foundation and are provided for informational purposes only.
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