Since drinking often leads to drowsiness, it seems logical that having a glass of wine before bed could help you rest if you're struggling to fall asleep. That's not quite true, though. While alcohol can make you fall asleep faster, the trade-off is that the sleep itself won't be any good. 

"Unfortunately, alcohol never improves sleep. Although alcohol helps you relax, making falling asleep easier for some, three to four hours after falling asleep, people wake up and can't get back to sleep. Conversely, people dependent on alcohol can't fall asleep if they don't drink," says Dr. John Mendelson, founder of Ria Health and a clinical professor of medicine at the University of California, San Francisco. 

If you have trouble falling asleep, consider swapping out the nightcap for relaxing activities in your nighttime routine. It can be anything that helps your body wind down: reading a book, taking a bubble bath or doing yoga poses before bed.

How does alcohol affect sleep?

Alcohol is a central nervous system depressant, which is why it gives you that pleasant, relaxed feeling. It's why so many of us fall asleep after drinking, and why it can seem like alcohol helps you sleep. How alcohol affects your sleep isn't a single, straightforward thing, because there are several ways that alcohol consumption influences the quality of sleep you get. 

To be clear, we're not just talking about binge or heavy drinking; a drink or two that is too close to bedtime can have a big impact on your sleep.

Here are four ways that alcohol affects your sleep.

Alcohol disrupts REM sleep 

Its relaxing properties make alcohol seem like a surefire way to sleep at night. However, the quality of restorative, restful sleep decreases. Research has shown that alcohol use interrupts your sleep cycle, particularly REM sleep. Remember, REM sleep is where dreaming happens.

"Evidence now suggests the deeper sleep of alcohol is also associated with an increase in frontal alpha waves, markers of wakefulness, and sleep disruption. Thus the deep sleep of alcohol is likely not to be restorative," says Dan Ford, sleep psychologist and founder of the Better Sleep Clinic.

So while you may initially fall asleep quicker, you aren't getting the benefits of REM sleep through the night. When you don't get enough REM sleep, you won't feel rested, and you'll see that influence your performance the day after. Studies have shown that daytime alertness decreases the day following a night of heavy alcohol consumption. 

You wake up more often after a few drinks

We mentioned that alcohol is a central nervous system depressant. This means the excitatory nerve cells in your brain are suppressed, so you fall asleep. But for most people, it doesn't last long. As your body metabolizes the alcohol, the excitatory nerves rebound. This process can cause you to wake up and experience trouble getting back to sleep. 

While this is common, it doesn't happen to everyone. To those I say, consider yourself lucky. This side effect happens to me almost every time I have a drink at night. Sure, the cocktail is fun while it lasts, but let me tell you, when I'm staring at my ceiling at three in the morning, I wish I would have skipped it altogether. 

Alcohol suppresses melatonin production in our bodies

Our bodies produce melatonin to help control our sleep-wake cycle, which happens to coincide with sunlight. Our pineal gland releases melatonin as the sun goes down, and we start feeling tired. When you drink, you're essentially throwing your sleep-wake cycle off.

Alcohol consumption decreases melatonin production -- regardless of whether the sun is down. One study found that drinking alcohol an hour before you go to sleep can suppress melatonin production by 20%.

We know what you're thinking: I can just take a melatonin supplement and combat the side effects. Not so fast; it's not recommended to mix alcohol and melatonin. Potential side effects can include anxiety, high blood pressure, dizziness or breathing problems. On a larger scale, mixing the two can affect your liver's ability to produce certain enzymes. 

Alcohol can amplify the effects of sleeping disorders 

In the case of obstructive sleep apnea, where the throat muscles and tongue are already impeding on your airway, alcohol makes the condition worse. When you drink alcohol before bed and have sleep apnea, your throat muscles will be even more relaxed and collapse more often, which translates to frequent breathing interruptions that last longer than normal. 

Research suggests alcohol consumption increases the risk of sleep apnea by 25%. It also contributes to the lowest oxygen saturation levels in patients with obstructive sleep apnea. Oxygen saturation measures how much oxygen is in your blood and how effectively it's able to carry it to your brain, heart and extremities. 

Alcohol can also worsen insomnia, the most common sleep disorder, which is marked by difficulty falling asleep, waking up through the night or waking too early in the morning. 

It's estimated that between 35% and 70% of people who drink alcohol live with insomnia. It's a little bit of a chicken and an egg situation -- troubles with insomnia can be made worse by alcohol consumption. And insomnia has the potential to contribute to alcohol dependence. 

On the surface, alcohol's sedative effects can feel like they would ease the symptoms of insomnia and help you fall asleep. But given the likelihood of REM sleep disruptions and frequent waking, it's not recommended that anyone use alcohol to treat their insomnia symptoms. 

How to sleep better after drinking alcohol

You can still enjoy a drink and sleep well. Use these tips to make sure your favorite cocktail never keeps you up at night.

Pay attention to how alcohol impacts your sleep

You should be aware of how alcohol affects you and your sleep schedules. "Keep a sleep log to measure duration and quality and add to that log drink quantity and times to see if you notice patterns related to sleep quality," Mendelson advises. 

It can be as involved or simple as you want. You can log it in a journal or just check in with yourself in the morning. The impact alcohol has on your sleep will be specific to you. If you're making an effort to pay attention to how it affects you, you can set limitations for your body and needs. 

Stop drinking at least four hours before you go to sleep

You can still enjoy a cocktail and get good sleep. There's no need to swear off alcohol entirely, but timing your drinks can be the difference between sleeping through the night and tossing and turning. 

"If you choose to drink alcohol, drink in moderation and stop at least four hours before bedtime to avoid its negative effects on healthy sleep," advises Dr. Raj Dasgupta, assistant professor of clinical medicine at Keck School of Medicine at the University of Southern California.

To put that in perspective, four hours before you sleep is roughly dinner time for most people. Four hours is a good benchmark because it gives your body time to metabolize the alcohol to ensure it won't impact your sleep. 

Too long, didn't read?

We're not here to tell you a drop of alcohol will ruin your sleep quality. However, there are a few nuances that you'll run into. Drinking alcohol, specifically within four hours before you go to bed, may help you fall asleep quicker but ultimately reduce your REM sleep and will potentially wake you up later. Timing your cocktails or swapping out your drink for a mocktail is a great way to ensure you'll sleep soundly through the night. 

The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.