This study examined the effect of adding 2-hours of sleep every day on performance measurements of college basketball players. They found a significant improvement in 94-yard sprint times when players had more sleeping time. The good news is that studies show you can achieve more overall sleep time through naps so don’t be afraid to take a cat nap to improve your fitness and performance.
Reference: Mah, C. D., Mah, K. E., Kezirian, E. J., & Dement, W. C. (2011). The effects of sleep extension on the athletic performance of collegiate basketball players. Sleep, 34(7), 943-950.