Why Alcohol Is Bad for Sleep

Analysis by Dr. Joseph Mercola Fact Checked

effects of alcohol

Story at-a-glance -

  • Behavioral studies support the notion that having two or three drinks before bed helps promote sleep, but this is short-lived
  • Within just a few days, the sleep-promoting effects of alcohol diminish, while in the longer term, alcohol use is linked to sleep disturbances
  • Alcohol is a short-acting sedative and a rebound will occur, with arousal increasing about two to three hours after your blood alcohol levels decrease to zero
  • A rebound of rapid eye movement (REM) sleep may occur during this arousal phase, during which intense dreams or nightmares may occur
  • Ultimately, your sleep becomes fragmented while even the initial sedative effects will wane as your body develops tolerance, typically after three to seven days of alcohol use
  • Those who drink alcohol in the evening are also less alert during the day and more tired than those who do not

The University of Sussex conducted a survey to find out what happened when 800 people took part in “Dry January,” or abstaining from alcohol for the first month of the year. A number of benefits were reported, from losing weight to saving money, but one stood out from the crowd: 7 out of 10 people who stopped drinking alcohol for one month reported sleeping better.1

Considering that one-third of U.S. adults say they don’t get enough sleep,2 this is a significant benefit — one that could have major health implications for those who choose to imbibe regularly. In the time period spanning 2001/2002 to 2012/2013, the number of people who reported drinking alcohol in any amount shot up from 65.4% to 72.7% of Americans.3

About one-third of them engage in “high-risk drinking,” which was defined as five or more standard drinks for men or four or more drinks for women at least once a week. Among women, this type of binge drinking increased by 57.9% percent over the study period.4 Alcohol is often used as a sedative,5 enjoyed with the intent that it may help you unwind and relax at the end of the day.

General population studies suggest that up to 28% of adults have used alcohol as a sleep aid, typically for less than one week at a time, although 15% have used alcohol to promote sleep for more than four weeks.6

Behavioral studies support the notion that having two or three drinks before bed helps promote sleep, but this is short-lived. Within just a few days, the sleep-promoting effects of alcohol diminish while in the longer term, alcohol use is linked to sleep disturbances.7 More daytime sleepiness is also reported in those who used alcohol as a sleep aid.8 But what is it about alcohol that interferes with sleep?

How Your Sleep Changes When You Drink Alcohol

Alcohol can have either stimulating or sedating effects, depending on the dose and timing in relation to bedtime. In the first hour after consuming a small amount of alcohol, stimulating effects occur as your blood alcohol levels rise. If you consume a large amount of alcohol, it will lead to drowsiness as your blood alcohol levels fall.

As for moderate alcohol consumption (two to three standard drinks of 12 ounces of beer, 5 ounces of wine or 1.5 ounces of spirits), dose-dependent sedation may occur that lasts for several hours.

Typically, sleep latency, or the time it takes you to fall asleep, gets shorter with more drinks, up to six total. However, alcohol is a short-acting sedative and a rebound will occur, with arousal increasing about two to three hours after your blood alcohol levels decrease to zero.9

A rebound of rapid eye movement (REM) sleep may occur during this arousal phase, during which intense dreams or nightmares may occur. Ultimately, your sleep thus becomes fragmented while even the initial sedative effects will wane as your body develops tolerance, typically after three to seven days of alcohol use.

In the long term, it’s unknown how moderate alcohol consumption affects sleep, but according to a review of 107 studies published in the journal Substance Abuse, long-lasting changes may occur:10

“Late afternoon (‘happy hour’) drinking, as much as six hours before bedtime, also disrupts sleep, even though alcohol is no longer in the brain at bedtime. This phenomenon suggests a relatively long-lasting change in sleep regulation.”

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Evening Drinking Reduces Daytime Alertness

Using alcohol as a tool to fall asleep can have consequences the next day, too. Even if you’re well-rested, “reduction in alertness enough to impair performance occurs in the morning after evening drinking,”11 research shows, and your reaction time can be impaired even when your blood alcohol levels are zero. Overall, those who drink alcohol in the evening are less alert during the day and more tired than those who do not.

The risks may be especially significant for those who are already sleep-deprived, as even drinking a small amount the night before could raise the risk of traffic-related and other accidents due to severe daytime sleepiness. “Most worrisome is moderate alcohol use among chronically sleep-deprived populations such as shift workers and young adults who are at high risk for falling asleep while driving,” the researchers noted.12

Older adults should also think twice before using alcohol as a sleep aid. A 30-year study of 6,117 older adults found that men who drank more than 21 units (about 168 grams or 6 ounces) of alcohol per week were more likely to wake up several times during the night than those who drank no alcohol.

Those who maintained this level of drinking, or had an unstable alcohol consumption pattern, over the three decades of observation, were also more likely to wake several times during the night and wake up feeling tired.13 “Those with disrupted sleep should consider reducing alcohol consumption and people in this age group, particularly men, should be discouraged from using alcohol as a sleep aid,” the researchers concluded.14

Despite this, in a survey of people aged 60 and over regarding why people change their alcohol consumption later in life, 6% of men and 5% of women said they started drinking more alcohol as a way to help get to sleep.15

During Sleep, Alcohol Affects Your Heart, Breathing and More

During sleep, your body engages in important physiological restoration. Your autonomic nervous system (ANS) relaxes, but if you don’t sleep well it interferes with this process while also impairing regenerative processes and triggering metabolic disturbances.16

Finnish researchers were intrigued to find out whether alcohol intake, in turn, affected the ANS during sleep, so they tracked heart rate and heart rate variability (HRV), a measure of the variations in time elapsed between your heartbeats, among 4,098 people during the first three hours of sleep. HRV is a measure of your heart’s ability to respond to physiological and environmental stress stimuli, which, in this study’s case, was alcohol intake.17

A dose-dependent disturbance of cardiovascular relaxation during sleep was noted in relation to alcohol intake. Specifically, HRV-derived physiological recovery state decreased by 39.2% with high alcohol intake (defined as more than 0.75 grams per kilogram (g/kg) of body weight), 24% with moderate intake (>0.25-0.75 g/kg) and 9.3% with low intake (≤0.25 g/kg). Regular physical activity or being young in age did not protect from this disturbance.

Alcohol also affects other aspects of sleep, and even one drink is linked with snoring in otherwise normal sleepers, while moderate drinking can lead to obstructive sleep apnea (OSA) that leads to oxygen desaturations. The Substance Abuse researchers explained:18

“Alcohol relaxes upper airway dilator muscles (decreasing airway patency) increasing nasal and pharyngeal resistance, and it prolongs the time required to arouse or awaken after an apnea occurs. Alcohol also selectively depresses hypoglossal nerve activity and alters carotid body chemoreceptor function.”

Among people with OSA, drinking alcohol may be especially problematic, as it may make the frequency and severity of apneas worse, while increasing the risk of heart attack, stroke and sudden death. The risk of sleep-related accidents is also noteworthy:19

“Alcohol’s worsening of apneic events, increasing sleep disruption and daytime fatigue, can also impair driving and increase rates of motor vehicle accidents. Among OSA subjects who consumed 14 or more drinks per week, self-reports of sleep-related accidents are fivefold higher compared to those who drink lesser amounts.”

Other ways that alcohol consumption may impair and fragment sleep include the following:20

  • Increased movement disorders
  • Increase in periodic leg movements
  • Promotion of sleepwalking
  • An association with gastritis, esophageal reflux and polyuria (excessive urination)
  • Unsteadiness and falls during trips to the bathroom at night

Risks Related to ‘Impaired Sleep Homeostasis’

While alcohol may increase sleep during the first half of the night, sleep during the second half of the night is more likely to be disrupted if you’ve consumed alcohol, due to a disruption in sleep homeostasis.21 In a statement, Mahesh Thakkar, Ph.D., with the University of Missouri School of Medicine, explained:22

“The prevailing thought was that alcohol promotes sleep by changing a person's circadian rhythm — the body's built-in 24-hour clock," Thakkar said. "However, we discovered that alcohol actually promotes sleep by affecting a person's sleep homeostasis — the brain's built-in mechanism that regulates your sleepiness and wakefulness.

… Based on our results, it's clear that alcohol should not be used as a sleep. Alcohol disrupts sleep and the quality of sleep is diminished. Additionally, alcohol is a diuretic, which increases your need to go the bathroom and causes you to wake up earlier in the morning."

Lack of sleep and poor quality sleep, in turn, can raise your risk of chronic and acute health conditions. For instance, too little sleep may interfere with thyroid hormones and raise C-reactive protein levels (CRP), which may promote inflammation and increase the risk of Type 2 diabetes.23

Research also shows that adults who sleep less than six hours a night have a four times higher risk of catching a cold when directly exposed to the virus than those who get at least seven hours.24 Sleep is even connected with subclinical atherosclerosis, the early stages of hardening and narrowing of the arteries.

In one study, those who slept for less than six hours a night were 27% more likely to have subclinical atherosclerosis than those who slept for seven or eight hours a night.25,26 If you have trouble falling asleep, or you wake frequently during the night, it’s time to take steps to improve your sleep.

Top Steps for a Good Night’s Sleep

I do not recommend drinking alcohol, and if you’re using it as a form of sleep aid there are many other ways to get a sound’s night sleep that will leave your body truly refreshed. Be sure you’re sleeping in complete darkness, for starters, as light (even that from a night light or alarm clock) can disrupt your internal clock and your production of melatonin and serotonin, thereby interfering with your sleep.

In the morning, bright, blue light-rich sunlight signals to your body that it's time to wake up. At night, as the sun sets, darkness should signal to your body that it's time to sleep. You’ll want to keep the temperature cool, between 60 and 68 degrees F, and eliminate electromagnetic fields (EMFs). Ideally, shut down the electricity to your bedroom by pulling your circuit breaker before bed and turning off your Wi-Fi at night.

Other practical solutions include going to bed earlier and considering a separate bedroom if your partner is interfering with your sleep. And, as mentioned, avoid drinking alcohol, as it will likely cause you to wake up during the second half of the night and have fragmented sleep. For more tips, my 33 healthy sleep secrets provides a comprehensive list of strategies for a better night’s rest.