I could not fall asleep. As I tossed and turned, I thought 'Ok, it's only 1 am, I can still sleep a decent six hours.' 
I flipped over on my stomach. That position never worked for me. So I lay on back with my arms across my chest. 'Wait', I thought, 'I got home at 1. Therefore, it must be 2 am.' An hour less of sleep can change everthing. When you know you have to get up in five hours, your whole attitude towards sleep is thrown out the window. I didn't sleep at all that night.