Researchers in Holland had 11 men perform a 20-minute cycling endurance test in various scenarios.. One scenario was after a night with little or no sleep and then again after a full night's sleep. After each test, the athletes were asked to estimate the distance they believed they had covered over the 20 minutes. In both trials, the men cycled for an average of 7.6 to 7.7 kilometers, around five miles. What varied was how far they thought they biked. After a good night's sleep, the men estimated they had ridden 7.26 kilometers. Without sleep, that guess fell to just 6.51. It seems that the study is telling us that subjective estimates of performance are not in line with actual performance for endurance exercise after sleep deprivation.
In other words, lack of sleep might make you feel wimpier than normal. That's good news for anyone whose sleep suffers from game day jitters: Even if you're feeling less than your best, you won't necessarily run a slower race or ruin your tennis match. Still, no need to stay up late on purpose. Regularly getting even just one extra hour of sleep a night has been shown to improve athletic performance, even if more sleep means less time to do other things.