How Does Alcohol Impact REM Sleep?

You’re having trouble falling asleep almost every night. You lay there, staring at the ceiling, your mind spinning with to-dos as you think about everything you didn’t get done today and still have to do tomorrow. Interestingly, you notice that on the nights that you have a glass of wine with dinner, your mind quiets down. You start to get sleepy and easily doze off as soon as your head hits the pillow. You're blissfully asleep until suddenly, several hours later, you wake up and are wide awake. What’s going on?

You’re not imagining things. Alcohol really does help you fall asleep faster and more easily. This is because alcohol is a central nervous system depressant: it slows our brain activity. It also acts as a sedative, inducing feelings of relaxation and sleepiness.

But here’s the problem: even though alcohol can cause us to fall asleep quickly, it negatively affects our overall quality of sleep. In fact, the consumption of alcohol — especially large amounts — has been consistently linked to poor sleep quality and duration. More specifically, alcohol suppresses rapid eye movement (REM) sleep, one of the most important stages of sleep for physical and mental restoration. Let’s take a closer look.

Understanding Our Sleep Cycle

To understand how alcohol impacts REM sleep, it’s important to understand the different stages of the human sleep cycle. Over the course of the night, we go through several complete sleep cycles, each of which is composed of four individual stages. On a typical night, we’ll go through four to six sleep cycles, which last about 90 minutes each.

Here are the four different stages of a sleep cycle:

• Stage 1 (light sleep): This is when we first fall asleep. Our body isn’t fully relaxed, and our brain activity starts to slow with periods of brief movements. This stage normally lasts from 1-7 minutes. It’s usually pretty easy to wake someone up during this time.
• Stage 2 (light sleep): This is when our body enters a more subdued state including a drop in temperature, relaxed muscles, and slowed breathing and heart rate. This stage can last for 10-25 minutes during the first sleep cycle. We typically spend about half our sleep time in this stage of sleep.
• Stage 3 (deep sleep): During this stage, our muscle tone, pulse, and breathing rate decrease as our body relaxes even further. Because of this, it’s much harder to wake someone up if they’re in this phase. This stage is also referred to as “delta sleep” or “slow-wave sleep,” as our brain activity during this period has a pattern of what are known as delta waves. We usually spend about 20 to 40 minutes in this phase.
• Stage 4 (REM sleep): We typically enter rapid eye movement (REM) sleep about 90 minutes after we initially fall asleep. Even though our eyes are closed, they can be seen moving quickly, which is how this stage gets its name. There is a significant uptick in brain activity, and our breathing rate and heartbeat quicken. We also experience the most vivid dreams in this stage, which usually accounts for about 25% of our sleep time.

REM sleep is vital for cognitive functions like memory consolidation, emotional processing, learning, and creativity. For instance, during REM sleep, our brain processes the day’s new lessons and motor skills, committing some to memory, maintaining others, and deciding which ones to delete. Researchers suggest that REM sleep also promotes brain development, since newborns spend most of their sleep time in REM (8 hours a day!).

Study after study demonstrates the importance of REM sleep. REM sleep deprivation interferes with memory formation and negatively impacts our mood and mental focus. Lack of REM sleep can even weaken our immune system, as the growth of new healthy cells and tissue in the body is blocked.

How Alcohol Affects REM Sleep

Alcohol suppresses and reduces the amount of time we spend in REM sleep. As we’ve noted, alcohol initially acts as a sedative, increasing the proportion of deep sleep at the beginning of the night. However, as alcohol’s effects start to wear off, our body spends more time in light sleep, which can result in shorter sleep duration and more sleep disruptions. This is why we tend to wake up frequently after drinking once several hours have passed.

Even just a couple of drinks can have a negative effect. For instance, one study found that having fewer than two servings of alcohol per day for men or one serving per day for women decreased sleep quality by nearly 10%. The more alcohol we consume, the more our quality of sleep decreases: more than 2 drinks for men and more than 1 for women decreased sleep quality by almost 40%.

Alcohol also increases levels of adenosine, a key component of the homeostatic drive, which is responsible for keeping our body balanced. It’s also one of the major mechanisms regulating our sleep-wake cycle. The homeostatic drive tells us it’s time to sleep by boosting levels of adenosine when we’ve been awake for too long.

After a few drinks, increased levels of adenosine send us into a deep sleep. But, once our body realizes it’s had too much slow wave sleep, the homeostatic drive compensates by allowing us less deep sleep in the second half of the night. This is why we might find ourselves tossing and turning.

Without adequate sleep, our cognitive functions and performance start to decline. We might find ourselves forgetting things more often or having difficulty concentrating. Over time, lack of REM sleep and chronic sleep deprivation can lead to serious health issues such as diabetes, depression, obesity, and cardiovascular disease.

The Bottom Line

It can be tempting to turn to alcohol as a sleep aid. But, even though it can help us fall asleep, the effects are short-lived and we don’t end up getting the restorative sleep we need to function well. Even just one or two drinks can be harmful. The alcohol in our system causes us to spend less time in the important REM stage of sleep, ultimately causing us to wake up feeling less refreshed. In fact, fatigue and poor sleep are signs our body is telling us to drink less alcohol.

If we’re struggling to fall asleep, there are healthier alternatives to alcohol. For instance, there are multiple mindfulness techniques we can use to promote relaxation and help quiet our mind. We can also try incorporating meditations for stress relief.

If you regularly turn to alcohol to help you fall asleep, consider downloading Reframe. We’ve helped millions of people cut back on their alcohol consumption and develop effective skills for better managing stress and getting a good night’s sleep.