I have an issue when I take a nap during the day. Sometimes I can snooze with no problem, but when I'm trying to fall asleep, even if I have my eyes wrapped up with two blindfolds, my eyes will eventually creep open and I'm awake because I'm aware of the slightest amount of light.

The problem is that I'm "aware" of the surroundings now with my reality checks, and it's hard to be "aware" with reality checks and at the same time just let yourself drift off in the middle of the day.