How Alcohol Affects Your Sleep
Written by Leslie K. Hughes
Medically reviewed by Dr. Monique White-Dominguez
While you may find yourself falling asleep quicker than normal after imbibing, you may be surprised to find that the sleep you’ll be getting that night won’t be your best.
Some people pass out solidly after a night of festivities but are likely unaware that their bodies will pass through different phases of sleep that make for a restless night.
If you’re curious about the science behind how alcohol affects your sleep, read on to learn more.
The Ways Alcohol Affects Your Sleep
Studies have been done on how alcohol can change your sleeping patterns and researchers found that alcohol disrupts the phases of sleep your body experiences when in rest mode.
Stages of Sleep
Let’s get into the details of the different stages of sleep you encounter at night.
1. Wake
The first stage of sleep is the one in which you are still technically awake, but are starting to transition into sleep. During this stage, both alpha and beta waves are present. As you go deeper into Wake, beta waves become dominant.
2. NREM1 (first phase of non-rapid eye movement)
You move into this second phase immediately after falling asleep and only stay in this stage for a maximum of 10 minutes. Sleep is light here, but it is during this time that your heartbeat and eye movements start to slow down and your muscles relax. Your brain activity decreases here, too.
3. NREM2 (second phase of non-rapid eye movement)
This phase lasts a bit longer than NREM1 – about 30-60 minutes and is the longest phase of the sleep cycle. Your muscles go into a more relaxed state and your brain activity is likely to shift from beta waves to delta waves. You can expect your body temperature to decrease as well.
4. NREM3 (third phase of non-rapid eye movement)
Once you enter this phase, you are in deep sleep and it is difficult to wake up. NREM lasts anywhere from 20 to 40 minutes and your delta brain activity increases here. While your brain is busy, your body is in its deepest state of rest as your heartbeat, your breathing rate, and your muscles relax.
5. REM (rapid eye movement)
About 90 minutes after you fall asleep, you’ll find yourself in the REM stage. This is also known as the dream state, as this is where most of your dreaming happens. Interestingly, your brain paralyzes your muscles in this state so you don’t act out your dreams in real life. In the REM phase, your eyes are likely to flutter and your breathing is likely to become irregular. Some people suffer from sleep apnea, which means that you stop breathing when in the REM stage.
A typical night of sleep takes you through the cycle of these phases over and over, with each sleep cycle (from Wake to REM) lasting about 90-120 minutes. This means that if you’re getting a full eight hours of sleep a night, you’re moving through four or five sleep cycles. As you get to the third, fourth, and potentially fifth cycle of the night, REM becomes the more dominant phase and lasts longer.
Stages of Sleep After Drinking
If you have a few drinks before heading to bed, chances are good that you’ll sleep deeply for the first couple of hours. That’s because at this point, the alcohol is still making its way through your bloodstream and it has a calming effect on a neurotransmitter in your body.
As the night progresses and the alcohol levels decrease in your body, your brain and body experience high levels of arousal, and your standard sleep cycles get completely derailed. Many people experience more intense dreams after they’ve been drinking and are more likely to remember them due to interrupted sleep. Though you’re entering REM sleep, you are not in it for as long or as deeply as you are on a night with no alcohol.
Alcohol and Insomnia
Insomnia causes people to struggle greatly with the quality of sleep as well as the length of sleep. Many people who suffer from insomnia are unable to get a full night’s sleep.
By drinking before bed, you are likely to experience the same symptoms as someone with insomnia. That’s because alcohol reduces your REM sleep and throws all of your regular sleep cycles off balance. For many, this leads to self-medicating with alcohol, but that only makes the problem worse. This is a dangerous cycle to get into that leads people to consume higher levels of caffeine and other stimulants during the day to stay awake and then turn to alcohol to calm down from those stimulants at night.
Other Issues
Alcohol is a known diuretic, so you can bank on the fact that you may find yourself waking up to use the restroom quite often throughout the night. This becomes even worse as you age.
Drinking may also cause you to snore more because it relaxes your body’s muscles, including the ones that regulate your breathing. This can be a major problem for people who suffer from sleep apnea, as drinking only makes this disorder worse.
When You Should Stop Drinking Alcohol Before Bed
How long before bed should you stop drinking alcohol? Though the idea of a nightcap sounds great in theory, in practice you are setting yourself up for failure.
It’s a good idea to stop any alcohol consumption at least three hours before going to bed, but four hours is even better.
In addition to that, keep the number of drinks you have to a minimum. That typically means two drinks for men and one drink for women. You want to set your body up for success, which means a good night’s sleep free of the stress that alcohol puts on your body.
