Never Say Yes to a Nightcap

How a drink before bed can destroy your dreams 

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The vicious cycle of the nightcap begins innocently. Jane has a snifter of cognac, to clear her head, to ease her to sleep. Why not? It's something civilized people do. So she does, and she slides into sleep a little more smoothly. 

But it's slightly less revitalizing than the sleep of sobriety. She doesn't hit the same cycles. The next day she is ever-so-slightly anxious, on edge. She yells at a co-worker. Jane never yells.

That evening Jane is only more cognac-inclined. The next morning she drops her phone, and it breaks. Jane never drops her phone. Weeks pass like this. With them, grad school application deadlines. Eventually everything is off. She's emptying bottles of Cholula over her omeletes, just so she can feel something. Before long, the only sleep she gets is while curled hiding in the back of a subway -- her boyfriend asked her to move out after she destroyed his paintings. Betrayed by her snoring (Jane NEVER snores), they find her, and it's the end of the line.


There is a culture of romance and sophistication around the nightcap. Rosie Schaap recently wrote in The New York Times:

... A nightcap should also be brown. There are plenty of clear eaux de vie and other spirits that are said to settle the stomach after a luxurious repast. But a nightcap is different from an after-dinner drink or digestif. I stick with the classics: top-shelf whiskey, good brandy (usually Cognac), a burnished, potent, amber liqueur. ...

Exactly. While we've known for a long time that alcohol and sleep disruption are fond bedfellows, that discussion most often revolves around heavy drinking. We've even seen that genes regulating circadian rhythms are shut down in people with alcoholism, but we accept talk of burnished amber liqueurs in moderation as simple joie de vivre.

Polysomnography of REM sleep [Wikimedia]

So is a drink or two actually bad? Well, few sleep experts would recommend any amount of alcohol within an hour before bed. But outside of that world, the anti-nightcap argument is only beginning to enter mainstream thought. If a lot is bad, a little is ... not as bad, but still not helping the overall situation. That's underscored this week by forthcoming research from the London Sleep Centre and University of Toronto. They describe, among other effects of alcohol on sleep, that as we drink more, we get less REM sleep early in the night. That means less dreaming. You're just sort of hurtled into this conscious-less void.

Instead of REM, that time is spent in deeper sleep phases -- which they say, interestingly, increases our likelihood of snoring. (Snoring can of course destroy relationships between entirely reasonable people.) And we don't even get the benefit from that extra deep sleep, because once the alcohol wears off, those deep sleep phases are so disrupted that the net overall effect is a less restorative night.

Then, alone and tired and dream-deprived, we take solace in ... more cognac?

Co-author Irshaad Ebrahim told the BBC, "Alcohol may help you fall asleep initially, but will interrupt your sleep later on in the night. Plus you may wake dehydrated and needing the loo ... One or two glasses might be nice in the short term, but if you continue to use a tipple before bedtime it can cause significant problems."

Yes, a tipple may be all it takes.