Sunrise the next morning.
I was always up early as it's incredibly difficult to sleep when you're in a room full of around 20 other people. Even with ear plugs I could still hear the howling wind, people talking in their sleep and general rustling of sleeping bags. I also found it really difficult to get to sleep as my body had an excess of adrenaline - still coursing around my system after a day spent doing somewhat dangerous stuff. Once asleep I didn't stay that way for very long as I had numerous nightmares - all anxiety dreams I suspect caused by the dangers faced during the day. Bit of a wimp aren't I?