How much worse is your chess near or passed bed time?

Last night I played some chess games, and when I analyzed them, I was amazed at the horrible blunders I made. I analyzed it last night though, which kind of contradicts my assurtion that sleep was the reason. After move 20, I'm sure I started playing at the 900 level. My opponent even got lazy and made mistakes, but I missed them all and gave my king away.

I don't have any problem with playing when I'm very tired.  Mostly because my chess sucks 24 hours a day.  :)

yes i have realized the same problem when i am tired. the mind performs at a lesser capability. even though i want to play chess i have disciplined myself not to play chess after a certain time to avoid poor play.