When you are training, you will need more rest to recover. Instead of the 8 hours, 9 is probably better. It's that last hour or two when you go into REM (rapid eye movement) sleep that the mind really restores itself. Miss that time and your concentration and reaction time may suffer.
One way to get there is to add 15 minutes of sleep a night until you wake up feeling totally refreshed. Then you'll be ready to give it your best.
How do you know when you are still a little short of your personal needs?