I'm taking bets on when I pass out at work today. I stayed out later than I planned, got about 2 hours of uninterrupted sleep and 2.25 hours of waking in 15 minute intervals. Systems failure is imminent!
At around 4:17, my head bounced off my desk. The painful jolt rattled my senses, but banished sleep sufficiently for me to make it to the end of the day. Hooray.