Alcohol and the Second Half of the Night

Of all the sleep myths, the nightcap is the most durable, and the reason is that the first part of it is true.

Alcohol is sedating. You do fall asleep faster. Anyone who has had two glasses of wine and been unconscious by half past ten has direct personal evidence, and direct personal evidence is very hard to argue with.

What happens after that

Two things, both in the second half of the night.

REM gets suppressed. REM sleep is concentrated in the later cycles and is heavily involved in memory consolidation and emotional processing. Alcohol reduces it, particularly early in the night, and the body tends to attempt a rebound later — which is why heavy drinking often comes with vivid, chaotic dreaming towards morning.

The night fragments. As the alcohol is metabolised, sleep becomes lighter and more broken. You surface repeatedly, sometimes without remembering it.

The 4am wake-up after a few drinks isn't bad luck. It's the alcohol wearing off, on schedule.

The result is a specific kind of tired

Eight hours in bed, technically asleep for most of them, and awake the next day feeling flat and emotionally thin rather than physically exhausted.

That's the REM loss. It's a different sensation from being short of sleep, and it's why a full night after drinking doesn't feel like a full night.

Other things it does

It relaxes the muscles of the airway, which makes snoring worse and can worsen sleep apnoea. It's a diuretic, hence the 4am trip. And it warms you, which is the wrong direction — your core temperature needs to fall for sleep to consolidate.

What we do, since we're not going to tell you to stop

We drink less than we used to and, more importantly, earlier. Finishing three or four hours before bed makes a noticeable difference — most of it is metabolised by the time you're asleep, so the sedation is gone and so is the rebound.

Wine with dinner at seven behaves very differently from the same wine at eleven.

And the honest note

If you're using alcohol regularly to get to sleep, that is worth taking seriously rather than optimising. It's the one item in this category where the answer isn't better timing — it's a conversation with a doctor.