When you are drowsy in the afternoon, your hourglass of mental power might be almost empty. When things do not work their way, they start experimenting with various variants of the sleep schedule.
Polyphasic Sleep: Facts and Myths | herbertkikoy.info
Maybe I should just listen to my body and do that intentionally? I don't fall asleep in movies I decided that from now on, past 1, I am not allowed to lie in bed and watch a movie.