New Review Updates Effects of Alcohol on Sleep
Many people enjoy a cocktail or two in the evening to unwind from the day and help them fall asleep, but there’s a widely-held misconception that alcohol helps people sleep better. A new review of all known scientific studies on the impact of drinking on nocturnal sleep in healthy people is dispelling that myth with scientific data.
The review, led by Chris Idzikowski, director of the Edinburgh Sleep Centre in Edinburgh, UK, is the first time all available research on sleep and alcohol has been collected. The results will be published in the April 2013 issue of Alcoholism: Clinical & Experimental Research.
Idzikowski explained, “It’s a good time to review the research and mythology around the impact of alcohol on sleep. Our understanding of sleep has accelerated in the past 30 years, which has meant that some of the initial interpretations need to be revisited.”
How alcohol affects our sleep
Our sleep consists of two basic states: rapid eye movement (REM) sleep, and non-rapid eye movement (NREM) sleep. People usually begin the sleep cycle with NREM sleep, followed by a very short period of REM sleep. That is followed by more NREM sleep, and more REM sleep. This cycle between NREM and REM sleep continues about every 90 minutes throughout the night.
The review found that alcohol, depending on the amount, reduces the amount of time it takes a person to fall asleep, and can cause a person to experience a deeper NREM sleep. However, it is likely to disrupt sleep later in the night, reduce REM sleep, and leave a person feeling less rested.
In addition, the researchers found that the more that is consumed, the greater the impact on increasing deep sleep earlier in the evening. This effect on the first half of sleep may be a reason why some people with insomnia use alcohol as a sleep aid. However, the effect of consolidating sleep earlier in the night is offset by having more disrupted sleep later on in the night.
One hypothesis is that alcohol acts like medications that are used for depression and anxiety,” he added. “Studies on patients with depression have identified that untreated patients had excessive REM sleep, particularly in the early part of the night, and that antidepressant medication suppressed REM sleep. Alcohol acts like antidepressants, reducing REM sleep particularly in the first part of the night. This impact of alcohol on REM sleep may explain the mood elevation and anxiety reduction associated with alcohol use.”
In summary, lead researcher Idzikowski said, “Alcohol on the whole is not useful for improving a whole night’s sleep. Sleep may be deeper to start with, but then becomes disrupted. Additionally, that deeper sleep will probably promote snoring and poorer breathing. So, one shouldn’t expect better sleep with alcohol.”
The researchers hope this alcohol and sleep review will help readers understand that short-term alcohol use only gives the impression of improving sleep, and it should not be used as a sleep aid.
Based on the review, the researchers also found that:
- The onset of the first REM sleep period is significantly delayed at all doses, and appears to be the most recognizable effect of alcohol on REM sleep, followed by a reduction in total night REM sleep.
- Alcohol’s effects on REM sleep in the first half of sleep appears to be dose related—low and moderate doses showed no clear effects on REM sleep in the first half of the night, while at high doses, REM sleep reduction in the first part of sleep is significant.
- When alcohol increases slow-wave sleep (SWS) during NREM in the first half of the night, it may also increase vulnerability to certain sleep problems, such as sleepwalking or sleep apnea in those who are predisposed.
- Alcohol can contribute to obstructive sleep apnea (OSA), a disruption in breathing during sleep. The negative effects are strongest in people who drink the most.
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