Alcohol and Sleep: The Pros and Cons of the Nightcap

By Melissa Blake, ND
Most likely, you can relate to the immediate impact of a sleepless night. Even a little less sleep may contribute to changes in mood, energy, learning, and appetite.1-3 The long-term consequences of sleep disruptions may be even more serious.4
Thankfully, a glass of wine or whiskey on the rocks is a great way to relax and promote sleep. After all, that’s why it’s called a nightcap. Right?
Well, it turns out that alcohol may not be the magic sleep aid we pretend it is, and it may do more harm than good. To understand alcohol’s impact, let’s first talk about rhythms.

Master biological clock
Our bodies have an amazing natural ability of keeping to a daily schedule via an internal 24-hour master clock.5 This clock contributes to the patterns, also known as circadian rhythms, of many biological activities including sleep-wake cycles, eating patterns, and body temperature regulation.5
Many of the things that we associate with a healthy lifestyle may positively impact circadian health. The same goes for the things we know aren’t good for us—including alcohol: Generally they disrupt our circadian rhythms.6
One way alcohol can disrupt our natural sleep-wake rhythm is by suppressing melatonin, our natural sleep hormone. Research suggests moderate alcohol intake can reduce melatonin by 20%.7
Disruptions to this rhythm can impact health in many ways, often first appearing as changes in sleep, mood, and energy, with eventual negative outcomes that can include weight gain, memory issues, digestive complaints, and changes in immune function.8

How did we fall (asleep) for it?
Approximately 20% of Americans use alcohol as a sleep aid.9 If alcohol is disruptive to our natural rhythms, how has it charmed some people into thinking it is the perfect bedtime companion?
Alcohol causes short-term drowsiness and contributes to a reduction in sleep onset latency, meaning it shortens the amount of time that it takes to fall asleep.10 Although this sounds like a great solution for people who find themselves lying awake for hours, sedation is not at all the same as natural sleep, and the overall negative impact on sleep quality outweighs immediate sleep-inducing benefits.10,11
Sleep scientist Matthew Walker, PhD avoids using the word “sleep” in connection with alcohol altogether and instead suggests alcohol “sedates you out of wakefulness.”11
Alcohol is also a muscle relaxant. Once again, it may sound like a great solution to any tension that could be interfering with sleep onset. The concern is that alcohol causes the muscles around the neck and throat to relax, which contributes to an increase in snoring, interrupted sleep patterns, and lower oxygen saturation.12,13
Although alcohol may help you feel drowsy and relaxed, the effects are short-lived.

Alcohol: not enough REM
The impact of alcohol on rapid eye movement (REM) sleep may create some noticeable effects.10
Ever wake after a restless night and feel irritable and moody? It may have been that you didn’t get enough REM sleep.10 Natural, restorative sleep follows a predictive pattern. Much of the first half of the sleep cycle is spent in REM sleep, which is necessary for mental restoration, including processing and regulation of emotions and memory formation. Alcohol disrupts REM sleep pattern and shortens the overall amount.10 This shift in sleep pattern can affect the quality of sleep; however, the impact of alcohol, at any dose, also affects overall quantity of sleep.10,14
As alcohol is metabolized and the sedative effect wears off, a lighter sleep occurs during the second half of the sleep cycle and with it, frequent awakenings related to:14

• Bathroom needs
• Night sweats
• Snoring
• Waking too early unable to return to sleep

Alcohol: the vicious cycle
​Using alcohol as a sleep aid can contribute to a vicious cycle of dependency.15
We’re not always conscious of the frequent “micro”-awakenings associated with our beloved nightcap and therefore may not associate poor sleep quality and next-day fatigue with alcohol consumption. We are tricked into thinking alcohol helped instead of harmed and continue to believe a drink or two is the answer.
So a habit of evening drinking is sometimes developed, and over time, tolerance for the sedative effects builds so that more alcohol is required for the same sleep-inducing effect.15
Poor sleep quality leaves us feeling drowsy during the day, and we might turn to caffeine to help clear the fog. Caffeine is a stimulant that can interfere with sleep patterns as well…so we reach for our bottle of choice to counteract the stimulating effects and rely on alcohol to “sedate us out of wakefulness.”11,15 A vicious cycle indeed!
The good news is that alcohol intake is modifiable. If you are a great sleeper who wakes rested every day, the occasional drink is likely not the end of the world.
For those who choose to enjoy the occasional alcoholic beverage, here are a few tips to reduce the impact on sleep:

1. Avoid the nightcap and stick to happy hour, allowing for several hours to metabolize some of the alcohol before bed.
2. Make it a social event and avoid the habit of drinking alone.
3. Avoid using alcohol as a sleep aid altogether and instead replace with herbal tea, deep breathing practice, and a sleep hygiene routine to support natural, restorative sleep.

To learn more about sleep and other general wellness topics, visit the Metagenics blog.
References:

1. Bolin DJ. Sleep deprivation and its contribution to mood and performance deterioration in college athletes. Curr Sports Med Rep. 2019;18(8):305-310.
2. Spaeth AM et al. Effects of experimental sleep restriction on weight gain, caloric intake, and meal timing in healthy adults. Sleep. 2013;36(7):981-990.
3. Patel SR et al. Association between reduced sleep and weight gain in women. Am J Epidemiol. 2006;164(10):947-954.
4. CDC. How does sleep affect your heart health? https://www.cdc.gov/bloodpressure/sleep.htm. Accessed April 23, 2021.
5. Gamble KL et al. Circadian clock control of endocrine factors. Nat Rev Endocrinol. 2014;10(8):466-475.
6. Gupta NJ. Lifestyle and circadian health: where the challenges lie? Nutr Metab Insights. 2019;12:1178638819869024.
7. Rupp TL et al. Evening alcohol suppresses salivary melatonin in young adults. Chronobiol Int. 2007;24(3):463-470.
8. Fatima N et al. Metabolic implications of circadian disruption. Pflugers Arch. 2020;472(5):513-526.
9. Breus JM. Alcohol and sleep: what you need to know. Psych Today. https://www.psychologytoday.com/us/blog/sleep-newzzz/201801/alcohol-and-sleep-what-you-need-know. Accessed April 26, 2021.
10. Ebrahim IO et al. Alcohol and sleep I: effects on normal sleep. Alcohol Clin Exp Res. 2013;37(4):539-549.
11. Walker M. Why We Sleep. New York, NY. Scribner. 2017.
12. Burgos-Sanchez C et al. Impact of alcohol consumption on snoring and sleep apnea: a systematic review and meta-analysis. Otolaryngol Head Neck Surg. 2020;163(6):1078-1086.
13. Kolla BP et al. The impact of alcohol on breathing parameters during sleep: A systematic review and meta-analysis. Sleep Med Rev. 2018;42:59-67.
14. Greenlund IM et al. Morning sympathetic activity after evening binge alcohol consumption. Am J Physiol Heart Circ Physiol. 2021;320(1):H305-H315.
15. Colrain IM et al. Alcohol and the sleeping brain. Handb Clin Neurol. 2014;125:415-431.