It's more I was trying to stay awake and failed, and so didn't go into a deep sleep--I actually sleep better during the day than I do at night, so light doesn't bother me, provided I actually fall asleep instead of dozing. I'm one of those people cursed with it taking forever to fall alseep--it can take me upwards of 30, 40 minutes to actually fall asleep, and if anything wakes me up completely during that time, the process starts all over again. ;_;