Sleeping It Off: How Alcohol Affects Sleep Quality

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young man asleep on a table while holding an empty beer bottle

Having a drink (or two) is one way to nod off more quickly, but how restful is an alcohol-induced slumber?

The latest research, published in Alcoholism: Clinical and Experimental Research, shows that while a nightcap may get you to doze off, you’re more likely to wake up during the night and may not feel as rested following your sleep.

Scientists reviewed 20 studies that included 517 participants who were tested in 38 sleep laboratory experiments. The volunteers drank varying amounts of alcohol, ranging from a low of one to two drinks, a moderate amount of two to four drinks, to a high of four or more drinks. While some experiments examined the results of only one night of drinking, others extended into several consecutive nights. Most of the participants were healthy young adults, and none had drinking problems.

(MORE: Sleeping Pills Linked with Early Death)

“This review confirms that the immediate and short-term impact of alcohol is to reduce the time it takes to fall asleep,” lead author of the study Irshaad Ebrahim, director of the London Sleep Center, said in a statement. “In addition, the higher the dose, the greater the impact on increasing deep sleep.”

This helps explain why so many people rely on alcohol to fall asleep, despite warnings from experts that it merely postpones and can worsen insomnia. “The effect of consolidating sleep in the first half of the night is offset by having more disrupted sleep in the second half of the night,” Ebrahim said.

That presents a more complicated picture of how alcohol affects sleep, and the trade-off may have implications for understanding how sleep can impact overall health as well. At all doses studied, alcohol increased deep or so-called slow-wave sleep (SWS) during the first part of the night. This type of slumber is associated with healing and regeneration of bones, muscles and other tissues, as well as maintaining a strong immune system.

“SWS or deep sleep generally promotes rest and restoration,” Ebrahim said, cautioning, however, that alcohol increases in this stage can worsen sleep apnea and sleepwalking in people who are prone to those problems.

(MORE: Can’t Sleep? It May Be Affecting Your Memory)

In contrast, drinking has long been known to reduce REM sleep, the deepest sleep stage in which most dreams occur and during which memories are likely stored and learning occurs. And the current review suggests that it’s the amount of alcohol people drink that may have the biggest effect on their sleep quality. One or two drinks, for example, can increase slow-wave sleep while not affecting deeper REM sleep. But more alcohol can cut into the time spent in the REM stage. So that nightcap may be helpful in getting you to doze off, while a wild night of heavy drinking is likely to make you more restless. Moderation, it seems, is the key to a good night’s sleep.

3 comments
sleeptech_1
sleeptech_1

curioserdave-  

I fully agree with your comments on alcohol and sleep. Find something else to ease the transition into sleep. Something non-stimulating, non-fattening, and non-alcoholic. An no lighted screens!. Congratulations on getting away from alcohol near bedtime. I wish more of my patients could follow your lead. 

As a professional sleep technologist for the last 30 years, please allow me a little fine tuning on your comments:

"Depth" of sleep is determined by how much stimulation it takes to awaken the sleeper, not by the brainwave activity. REM is called deep sleep because it takes quite a bit of stimulation to awaken you out of REM. REM, Non-REM and wake are all very, very different in the brain. Neither REM nor Non-REM are much like waking, and neither is 'most' like waking. 

Environmental noise being included in your dreams just before awakening does not indicate the depth of REM sleep. Waking to a noise does not tell you how much noise you slept through without awakening. Also, since many dreams do not occur in REM sleep you very easily could have been in Non-REM sleep just prior to awakening. 

N3 or 'delta' sleep is the sleep stage in which the sleeper moves the least. Very brief muscle twitches, vocalizations, and small movements of the limbs are common in REM sleep. The atonia of REM does prevent one from getting out of bed and acting out dreams, but small bodily movements in REM are common. Such movements in N3 sleep are very uncommon. 

curiouserdave
curiouserdave

Maia,

As a longtime narcoleptic, roughly 3/4 of my life, please allow me a couple of points from a slightly different perspective.

I was a musician for several years in my 20s and alcohol was a constant companion. During that time, my sleep onset events were markedly curtailed.I don't know of any supporting research, but I concluded that the inhibitive effect of alcohol on REM sleep was a positive event in my case. There was no effect on the cataplectic element of narcolepsy, but by that point I was quickly learning to avoid its triggers. Despite any anecdotal positives on sleep onset, all the other problems and pitfalls of excessive alcohol consumption led me away from including Dewars and Jose Cuervo as a regular part of my daily routine.

My other point is not specific to narcolepsy and that is the categorization of REM sleep as the "deepest" sleep period. It may be the period the sleeper moves the least, but this is the sleep period when the brain is most like its waking state. To prevent the body from acting out the dreams introduced during the REM period a state of catatonia, known as REM atonia, is induced wherein the motor neurons are not stimulated and thus the body's muscles do not move. Heart rate and respiration increase and brain wave activity approximates that of a period of wakefulness. Your own experiences with a phone, alarm clock or other environmental noises being included in your dreams prior to waking is additional proof of the actual light nature of this sleep period.

Not withstanding my points, your article is spot-on for most readers. Alcohol may make one fall asleep, but it doesn't result in restful sleep, especially over any extended period. One doesn't need a shot to sleep, one needs to discover why he/she can't sleep without it.

Peter Drake
Peter Drake

yup, i know its not good for sleep. you notice this if you have a couple of glasses of scotch a night. after the first night you start to feel tired all day. its the 1 and only reason i never became an alcoholic :/