As a completely anecdotal and medically irrelevant personal counterpoint, I actually frequently find myself having much better sleep after having had two glasses of good cognac before sleep. I've certainly not made a daily habit of it, nor do I recommend it to anyone else, but the observation is rather consistent for me.

I do have a host of sleep quality issues in general, and I'm a very pronounced "night owl". Perhaps that has something to do with it, I don't know.