Having a Night Cap? It Might Be Ruining Your Sleep

Alcohol and sleep

If you’re having trouble falling asleep, it can be tempting to reach for a little hot toddy to help calm you down and get you ready to snooze. But did you know that while alcohol can help induce that sleepy feeling, it actually has a detrimental effect on your sleep? The effects of alcohol last longer than you might think. Drinking in the late evening can interfere with your sleep that night. Moderation and timing are really the keys to minimizing those sleep-robbing effects of alcohol.

Is alcohol a sleep inducer?

How many times have you heard an evening drink referred to as a “nightcap?” Alcohol is one of the most commonly used sleep aids. Estimates vary, but as many as 15 percent of people may use alcohol to help them sleep. Among people with insomnia, that number is estimated to be significantly higher. But the effects of alcohol on your sleep are ultimately sleep-disruptive, not sleep promoting. While it’s true that alcohol can help relax you so you drift off to sleep, it ultimately gets in the way of good night’s rest by interrupting your normal sleep patterns.[1] While research shows that consuming alcohol occasionally near bedtime does shorten sleep onset (the time it takes to fall asleep), drinking regularly can actually diminish the early-in-the-night sedative effects of alcohol, as the body develops a tolerance to its sedating effects.[2]

Why does alcohol disrupt your sleep?

As the alcohol you’ve consumed metabolizes into sugar, rising glucose levels can cause wakefulness, fragmenting your sleep. Since alcohol causes dehydration, you may also find yourself awake due to extreme thirst. Yet another cause of interrupted sleep is a full bladder, thanks to alcohol’s diuretic effects.[3] With all of the negative effects that alcohol has on your body, it’s easy to see why you’re likely to find yourself awake a few hours after going to bed if you’ve been drinking. Drinking alcohol in too large amounts and too close to bedtime undermines a good night’s rest by altering sleep cycles, encouraging restless sleep, and reducing overall sleep time.[4]

Alcohol can also increase the symptoms of sleep apnea and snoring because it relaxes the muscles of the upper airway.[5] So not only does the person who had a few drinks lose sleep, so does his or her sleep partner! Too much deep sleep can bring a greater risk for sleep-disrupted breathing, including snoring and obstructive sleep apnea.

The effects of alcohol can last for hours

On average, it takes about one hour to metabolize one drink but the effects described above can linger much longer, depending on your weight, gender, and health.[6] Even if plenty of time has passed between the afternoon “happy hour” and your bedtime, chances are your sleep will be fragmented and you’ll wake up frequently. Evidence suggests alcohol produces changes in the body’s mechanism of sleep regulation, including alterations to normal periods of deep sleep and REM sleep, the two most restorative sleep phases. The more often you drink, the less you’re apt to fall asleep quickly after drinking – unless you drink more. Alcohol in the body at bedtime alters the sleep cycle, increasing time spent in deep, slow wave sleep early in the night.[7] That may sound like a good thing but the key to healthy sleep is maintaining the right balance of time spent in each sleep cycle. And don’t forget that the harmful effects can last into the next day. Do you remember how you feel that “morning after” you’ve indulged? Since you didn’t get a good night’s sleep and you’re probably dehydrated as well, you can’t expect to look or feel your best the next day. The more alcohol you consume, the worse these effects may be.

Can alcohol cause habitual sleep problems?

If alcohol consumption becomes a habit, its sleep-inducing effect can decrease, while its disruptive effects can increase. With regular drinking, sleep problems and daytime fatigue can become persistent. Once the sedative effects of alcohol wear off, you may find your sleep restless and easily interrupted by periods of wakefulness in the late night and early morning.[8] This fragmented sleep in the second half of the night can leave you feeling tired and unrefreshed when you wake for the day. It may also contribute to daytime tiredness, difficulty concentrating, and problems with performance. The lack of refreshing sleep may lead to oversleeping in the morning, which further disrupts sleep-wake cycles. Also, a deficit of REM sleep can make you feel tired, sluggish, and unfocused the next day, and may have negative effects on mood.

What can you do to fix the problem?

To avoid the negative effects of alcohol on sleep, it’s best to curtail drinking within four hours of bedtime. Once it enters the body, alcohol takes several hours to metabolize. This timeframe will give your body time to be largely free of alcohol’s effects before your night of sleep even begins. The amount you drink also makes a difference. A single drink may allow you to fall asleep and even experience a slight increase in deep sleep without disrupting the latter portion of your night’s rest. Several drinks, on the other hand, will be significantly disruptive to sleep quantity and sleep quality. Don’t just abstain from alcohol in place of an evening drink, choose another nightly ritual that feels good and is sleep-friendly. A hot cup of herbal tea, a short walk at twilight, or cozying up on the couch to watch a film or television program can take the place of an evening drink on the nights you choose not to consume alcohol.[9] You don’t need to forgo alcohol altogether. Light consumption of alcohol no closer than four hours before bedtime can allow you to enjoy a drink without undermining your sleep. The evidence is clear: even though many of us believe alcohol works like the sandman, it’s really an enemy of sleep. So, remember, for a really good snooze, you might want to skip the booze.

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