If I try to sleep during the day, it doesn't work, no matter how tired I am. I don't usually succeed in falling asleep at all...and whether I do or not, I feel lousy afterward, dull, dispirited, low in energy, and am quite likely to suffer a headache...kind of like a mild hangover effect. Accordingly, I do not normally try to take "naps" during the day, but reserve my sleeping for the nightime hours.