Regular schedule has me hitting the sack around 22:00 and up at 04:15. That's about 6h of actual sleep, giving myself 15m to wind down and actually fall asleep.

On nights when I can't sleep, I'm up until midnight and might wake up every hour to 90 minutes until the alarm goes off. I've ridden to work 3 days in a row on 3 - 4 hours of sleep before, and it's horrible. I consider taking the car, then usually get on the bike with the realization that the cool morning air will wake me up, but being closed in the cage I'm likely to zone out.