Comment by nemesisrobot

I've had the opportunity to sleep in a lot lately, and I've found that I feel physically and mentally the most rejuvenated around the 9 hour mark. Shorter than that and my thinking is on the sluggish side, and longer and I feel tired and unmotivated. Personally, I've found the time that I wake up to also be a factor. Waking up at 7 or 8 in the morning after 9 hours of sleep has me in a better mood than at 10 or 11 with the same amount of sleep.