I also sleep like utter shit. Haven't had a good night's sleep in 16 years, it feels like. Some are better than others, but for the most part, they're at best below average.
I've never made a late night purchase--not sober, anyway. Oh wait, that's not true. I bought my Alpha after my brother kept me up until 6AM after he came back from drinking with a bunch of his coworkers--and they came back with him. You have no idea how upset I was at him the next day, as weekends are 8-10 hour work days for me since coming back to school, and it's difficult to do that on an hour and a half of sleep (the sun came up in the 7 o'clock hour, and I wasn't in a deep enough sleep to sleep through it). That was a 5 Red Bull day.
For the most part, I just play with the backlight of my Suunto, which I keep on my bedside table.