I am very diurnal. I wake when the sun rises. I can go back to sleep for a little bit, but it's not worth it to my day for me to do so. From time to time I nap, and have certainly mastered the power nap, which will get me through the rest of the day and evening after ten to twenty mintutes. If I sleep much longer than that, it effects my sleep at night. If I nap after seven in the evening, I wont be able to sleep until well after midnight.