Scientific Spotlight: Alcohol and Sleep
Why drinking may be keeping you up at night.
Sleep is a big deal! A poor night of sleep makes the next day feel like a struggle and prolonged sleep deprivation has serious consequences. Sleep quality is vital for our physical and mental health. Lack of sleep can shorten our lifespan, increase risk of diseases, and reduce our cognitive functioning. Earlier this year I was interviewed on the Body Pod podcast to discuss the research on alcohol, cancer, and health (click to listen to episode 1 and episode 2—I discuss sleep in the second episode). Today, we are going to unravel the complicated relationship between alcohol and sleep.
Sleep Architecture
Before we jump into how alcohol affects sleep, let’s talk about sleep architecture also known as sleep stages. We often focus on how much sleep we get in a night and overlook sleep quality. Normal sleep patterns consist of 4 main stages that we cycle through approximately 6 times per night:
Stage 1: This occurs right after a person falls asleep and is very brief. It is easy to wake someone up.
Stage 2: At this point individuals’ muscles relax, breathing and heart rate slow down. Brain activity begins to slow down eye movement stops. About half of our sleep time is spent in this stage.
Stage 3: The body continues to relax further and enter into deep sleep or “slow wave sleep”. This sleep is restorative and important for several of our body functions including memory and our immune system.
Stage 4: REM (rapid eye movement) is the stage associated with dreaming. Our brain activity is similar to when we are awake, although most of our muscles are paralyzed which keeps us from moving around wildly. REM is thought to be key to support cognitive functions.
How Does Alcohol Impact Sleep?
The relationship between alcohol and sleep is a bit counterintuitive. Since alcohol is a depressant, one of the side effects using alcohol is feeling tired after consuming it. Alcohol acts as a sedative and while it makes it easier to fall asleep, it negatively impacts the quality of our sleep and sleep architecture. Even though you may have fallen asleep and felt like you slept enough, you may tired the next day. Why does this happen?
As soon as we fall asleep, alcohol immediately interferes with our natural sleep architecture. During the first half of the night, it increases the time we spend in slow wave (stage 3 sleep) and suppresses our REM sleep. As we sleep, our body continues to process alcohol and it leaves our system (approximately 1 standard drink per hour). When the alcohol is removed, so are its sedative effects. Once this happens, sleep becomes more disrupted and we are more likely to wake up in the middle of the night. Our brain compensates for the missed REM stages earlier in the night by going into REM rebound. This results in prolonged REM stages in the second half of the night and further disruption of our sleep architecture. This is the reason many people report experiencing vivid dreams after a night of heavy drinking. If you are interested in reading research on alcohol and sleep this article is a good starting point.
What is the Long Term Impact on Our Sleep and Health?
Alcohol is a toxin and it is disrupts sleep by disrupting our neurons responsible for regulating our sleep. Our neurons can recover from short term exposure, however if heavy drinking becomes a chronic pattern, alcohol can create permanent damage and irreversible change to our sleep architecture. This is a big deal! Sleep is vital to our health and functioning. It is something we can’t afford to sacrifice.
TIPS to Reduce Alcohol’s Impact on Sleep:
Be mindful of alcohol intake. Avoid drinking more than 2-3 drinks standard drinks per occasion, especially in the evening. Remember, reducing the quantity of alcohol improves the quality of sleep. Try to pace drinking (e.g., 1 drink per hour) so your body has time to metabolize the alcohol or opt not to drink at all.
Avoid using alcohol close to bedtime. Give your body time to process the alcohol so it is out of your system before you go to sleep. Remember your body processes alcohol at a rate of approximately 1 drink per hour, so if you drink 4-5 drinks leading up to bedtime, your sleep quality will be negatively impacted.
Try a personal case study. We have so many tools that provide feedback on our sleep (e.g., Oura ring, Whoop). We can see how alcohol impacts sleep quality. What differences do you notice on nights you drink vs. don’t? How does the number of drinks you consume impact your sleep? This may provide helpful information to inform your decisions moving forward.
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