it differs for me from day to day really. I worked at Lowe's and had to wake up at 4am every morning to get there on time and worked till 3pm. Id get home and not go to sleep till around 11. Most of the time i did fine but some times id just feel like ass and not be able to wake up. I would have to sleep in on my day off to get back into where i felt good only after 5 or so hours of sleep.