I used to be such a heavy sleeper. Give me five minutes and I would be knocked out, dead asleep, probably with a small smile on my face.
Now I need more than just five minutes. Who knows, probably 20 or even 100 minutes pass before I even fall into some kind of tortured stage of light sleep. The same thing keeps tormenting me, even though I tried to bury it. The slightest sound of the morning birds chirping, the dim light of grey outside, these wake me when I need it least.
So I used to be such a heavy sleeper, and I preferred it that way.
Edit: 5.20 am