Though an alcoholic drink may have you falling asleep quickly, sleep specialists say it’s the middle of the night where that drink comes back to haunt you. CNN’s Randi Kaye got all hooked up at University of Michigan’s sleep lab to see what happens after a martini or two.

Drinking alcohol before bedtime may cause people to fall asleep more quickly but can negatively affect sleep quality later in the night, according to sleep specialists at the University of Michigan Sleep and Circadian Research Laboratory. In an experiment, a participant consumed a martini before sleep, then underwent monitoring in the lab, comparing sleep data from a night without alcohol to the night after drinking.

The participant's results showed they fell asleep slightly faster and experienced more deep sleep early in the night after drinking alcohol. However, as the night progressed, their sleep became lighter and less restorative. The lab’s lead, Todd Arnett, explained that after alcohol is metabolized—typically about three hours after consumption—the sedative effect wears off, resulting in increased periods of light sleep, which are less beneficial for rest.

Additionally, the data indicated reduced airflow to the participant’s brain, a heart rate about ten beats higher, and a significant delay in rapid eye movement (REM) sleep on the night alcohol was consumed. REM sleep is important for memory consolidation and emotional regulation. According to Arnett, the aftereffects of disrupted sleep from alcohol may leave people feeling fatigued or unwell the next day. He warned that regularly using alcohol for sleep may contribute to the development of alcohol use disorders.

The general advice from sleep specialists is to finish any alcoholic drinks at least three hours before going to bed to minimise the negative effects on sleep quality.



How alcohol affects sleep

I came to this bar in Ann Arbor, Michigan with one assignment. Can I get a Grey Goose Martini? Very dry, with a lemon twist. To see how alcohol can impact sleep. Cheers! My sleep. To science. To research. After my martini, I'm destined to be a lab rat at the University of Michigan Sleep and Circadian Research Laboratory. .06! I told you! I am a lightweight! It's run by Todd Arnett. Even a couple of drinks close to bedtime will have an adverse effect on your sleep. In order to assess my sleep, the team wired me up. And then it was time for bed. So I give that to you. Now for comparison, I'd done this exact same thing the night before. But that first night, I hadn't had any alcohol to drink. Good morning. How are you? I'm ready for my results. You ready? Yes. How are you? As Todd explained, the screen on the left showed my results from the night I did not drink. On the right was the night I did drink. I definitely fell asleep faster on the alcohol night. You did. You fell asleep a little bit faster. We've got more deep sleep here toward the beginning of the night with alcohol, compared to deep sleep here on your first night in the lab without alcohol. Deep sleep sounded good to me, but I was in for a rude awakening. Todd pointed out when what he called my sleep architecture began to crumble, all because of the alcohol I drank. But this shows that the sedative effect of alcohol ends about 2 a.m. for me. And then I have much lighter sleep. You have a lot more yellow, which is that really light stage of sleep, not restorative. So the rule of thumb I use is one drink takes about three hours to be fully metabolized. And by halfway through the night, alcohol has left your body, fully metabolized it, and so the second part of the night you're really in a state of withdrawal from the alcohol leaving your body. Todd says if you have a hankering for an alcoholic beverage, finish it three hours before bed or more. Happy hour seems a better idea these days. Todd also said there was a reduction in airflow to my brain, and my heart rate was 10 points higher. That's more stress on my heart. Your rapid eye movement sleep on the alcohol night was significantly delayed compared to the first night. And that's common, again, with the acute effects of alcohol, that it suppresses dream sleep early in the night. REM sleep, that's thought to be associated with memory consolidation, emotion regulation. And so someone who hasn't slept well from alcohol, how do they feel in the morning? They might feel like they're fatigued. They just feel sometimes unwell. I mean, sometimes people can feel sick to their stomach. How pervasive or urgent of a problem is this, in your opinion? It's a major problem, I think, and using alcohol for sleep difficulties can be a pathway to alcohol use disorders or more significant alcohol misuse problems. The message is clear. Don't count on alcohol to get you counting sheep.

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