The biggest change is that I used to get migraines from lack of sleep (even while sleeping 8-10 hours plus occasional naps). Now I can get 6 a night continuously and be more alert. But most importantly my quality of life improved drammatically on account of having probably 30 hours a week of migraine-hours removed.

I still occasionally get lack-of-sleep-migraines, but they are rare, and are usually well deserved (I have three children, a puppy, and an unwillingness to give up 'alone time' in order to sleep enough. It's a bad combination).