I think this is very common. I haven't drank since April 20 and I sleep very soundly now, actually fall asleep when my head hits the pillow and don't wake up until the alarm goes off. I think you are catching up on a lot of REM sleep that is so disrupted while drinking, that and your body is working hard to repair itself and needs a lot of rest. I still sleep great but have noticed that in the last month I haven't felt the exhaustion I felt earlier. It does get better, beats a nasty hangover anyday!