I am one of those people that takes a hugely long time to get into a deep sleep.
Any kind of irregular/arrhythmic noise will keep me wide awake and if I hit hay at 11 I probably won't be out til about 1/2am
Once I AM asleep you could drop a house on me and then I'm wide awake at 6.30 on the dot, even on Sundays.
It fucking sucks. I can make do with the hours I get usually but when the pressure's on from time to time I sorely miss that shut eye.
Tl; dr - light sleepers have it bad.