I am pretty sure now that the more you are stressed the more your body could use sleep. I usually only need about 7-8 hours of sleep to feel rested. Once I started to get broken sleep I started getting headaches all day. Responding to night pages for work, and being frustrated all day means more stress. Also, my wife and I are closing on a house this week and will be in the midst of a move for the next 10 days – that means more stress. I got a solid 7.5 hours of sleep and I am unbelievably tired this morning. So my conclusion here is that more stress means you need more sleep.