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What alcohol actually does to your sleep cycle

Apr 28, 2021

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Read time: 8 min

Key points

Drinking alcohol disrupts your circadian rhythm, so you spend less time in the restorative REM stage of sleep.
Over time, low-quality sleep impacts your brain power and immune system, and increases your risk of chronic disease.
Safe and effective methods to improve sleep include guided meditations, blackout curtains, and cognitive behavioral therapy for insomnia (CBT-I).

Ever hear that a drink or two of alcohol will help you sleep? Plenty of people think so, probably because they fall asleep more quickly when drinking. But alcohol actually doesn’t help with sleep—in fact, it’s quite the opposite. “You may be confusing quality sleep (aka better sleep) and quantity of sleep, or how quickly you can fall asleep (aka sleep onset latency),” says Dr. Michael Breus, a fellow of the American Academy of Sleep Medicine in Manhattan Beach, California.

In other words, alcohol can help you fall asleep faster, but it negatively affects your sleep so much that you’ll actually be less rested. The more you drink, and the closer to bedtime, the less restorative your sleep will be.

Your sleep cycle

All sleep is not created equal. When you hit the hay, your body should go through four individual sleep stages in one complete cycle.

Stage one

Your first few minutes of dozing are your lightest. During this phase (which typically lasts less than 10 minutes) your brain produces alpha and theta waves, slowing down your thoughts and your eye movements. In this stage, you can be easily woken.

Stage two

During stage two sleep, you truly begin to power off: Your muscles relax, your heart rate slows, your body temperature drops, and eye movements stop entirely. Your brain activity also starts to slow down.

Alcohol increases slow-wave sleep, which throws off your circadian rhythm.

Alcohol contributes to sleep disturbances in the second half of the night.

Slow-wave sleep

As your body moves into the deep-sleep zone, your brain produces slower delta waves and it’s much harder to wake you up. This is often called slow-wave sleep, and it’s critical for allowing your body to repair tissues, boost immune function, and generate energy for the next day.

REM sleep

The first three sleep cycles take about 90 minutes to cycle through—then you hit REM (which stands for “rapid eye movement”) sleep. “REM sleep is when we move data from our short-term memory to our long-term memory,” explains Dr. Breus. “If we can’t do that, we can’t answer questions, make decisions, etc.” In other words, it’s critical to be able to function at your best.

Alcohol and sleep

It is true that alcohol—whether it’s just one drink or a long night out—reduces sleep onset latency (aka makes you fall asleep faster). But again, that doesn’t mean it’s good for sleep. Alcohol mainly impacts the second half of your sleep cycle, says Dr. Breus—the stages most vital to making sure you get the restorative slumber you need for the next day.

The first few hours

According to a meta-analysis of research published in the journal Alcoholism, drinking increases the amount of slow-wave sleep you experience during the first half of the night. It’s counterintuitive, but more deep sleep actually isn’t a good thing. As Dr. Breus explains, the imbalance can throw off your circadian rhythm, which is your body’s internal clock.

Spending more time in slow-wave sleep means you spend less time in the deeply restorative REM phase of sleep. The same study found that drinking at any amount “significantly delays” the onset of REM sleep.

The rest of the night

During the second half of the night, as the sedative effects of alcohol start to wear off, research shows you begin to experience micro sleep disturbances—perhaps small enough that you don’t even fully wake up—which further devalue the already diminished REM sleep you’re getting.

Translation? Over the course of the night, you get more lower-quality light sleep, and less high-quality restorative sleep.

Why it matters

A poor night’s sleep can have serious consequences for your brain and body. Over time, this creates a “domino effect” on your health.

Brain power

There’s a reason you feel like you’re always drawing blanks after a poor night’s sleep: Sleep is critical for higher-level thinking and creativity. A 2017 study of college students found that sleep deprivation slows your reaction time, which could make things like taking timed tests more difficult and activities like driving dangerous.

Immune system

Study after study has found that getting a poor night’s sleep (especially when it becomes a regular habit) has negative effects on your immune system. A 2017 study among twins found that “chronic short sleep” (meaning less than seven hours on average) contributes to immune system dysfunction. A previous study found that those who got an average of seven hours of sleep or less were nearly three times more likely to get a cold than participants who got eight hours or more.

Chronic disease

Several studies have linked insufficient sleep to an increased risk of chronic diseases like diabetes, hypertension, and heart disease. A study published in the Journal of the American Medical Association found that participants who got more sleep had a lower risk of coronary artery calcification, which could mean a lower risk of heart disease in the future.

Weight management

A poor night’s sleep can make you more susceptible to weight gain. A 2016 study found that not getting enough quality sleep may affect your endocannabinoid levels, aka the chemical signals that help regulate your appetite and your brain’s reward system.

How to sleep better...sober

To get a good night’s sleep, don’t turn to a glass of wine—there are plenty of effective, proven ways to help you upgrade your sleep and doze off quickly without sacrificing quality of sleep.

Turn your room into a Zen oasis and minimize distractions.
Plug in your phone to charge away from your bed so you’re not scrolling before you sleep.
Don’t bring your laptop or any other tech into bed.
Consider getting room-darkening curtains and a fan or a white noise machine to create the optimal sleep environment.
Listen to soothing music or a guided meditation before bed.
Set up a bedtime routine you love (maybe a nightly face mask or reading a chapter of a favorite book) and stick to it.
If you still struggle to get a good night’s sleep, look into cognitive behavioral therapy for insomnia (CBT-I), which has been shown to be highly effective in treating sleep issues.