James Hamblin summarizes forthcoming research from the London Sleep Centre and the 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?