Alcohol is actually both a stimulant AND a depressant. The first few glasses give us the buzz and makes us more energetic, talkative and lively. After that, the depressant factor kicks in, hence falling asleep/passing out later. Then the depressant part wears off, which is why your sleep is more restless and poor quality. It's a heck of a roller coaster ride, and something I really don't particularly want to get back on. I'm finding that yes, I'm tired in the evenings, but it's a natural tired - and sleep restores me now, rather than it being p*ss poor all night.