While I'm sure more sleep probably does boost fitness (and cognitive) performance, this study is pretty narrow in scope and tracks results of a women's tennis team. About the only semi-useful metric they track is the sprint times, but even that isn't very useful because the researchers didn't have a third phase of the study where the women were asked to decrease their sleep back to stage 1 amounts. Having a third stage would help control for performance increase due to practice time. The other metrics they track are highly variable in a sport such as tennis because players can put speeds and spins on the ball to affect the outcome. To control for this, you'd probably have to track a player's performance in a series of matches against the same opponent in addition to having a stage 3 like I described above. Still, tennis is more skill-based and less fitness-based compared to other sports like running, so I think it would be hard to draw conclusions from a study like this.
I don't see how athletes in what rjett calls fitness-based sports can scan sleep without impairing their health. I recall studies from years ago that showed athletes requiring more sleep than the general population.
I wish I could just "extend my sleep to 10 hours a night". However tired I am, I don't seem to be able to sleep more than 7, sometimes 8 hours tops - I just wake up naturally even if there are no sounds, distractions etc.
I don't have problems with having a 1.5-2 hrs nap during the day, but even if I have no naps and am very tired by evening, and go to sleep when I feel like going to sleep - I'll be awake in 7-8 hours and won't be able to sleep more.<p>My wife, on the other hand, is quite happy to sleep up to 11 hours whenever she gets a chance ...
Their rate of improvement over a 5-6 week period increased, but the article omits their baseline rate of improvement (presumably they're still-developing athletes). I didn't check if the actual study addresses this, and in any case, the improvements sound larger than usual.<p>Of course, it's also nearly impossible to create a placebo 10-hours-sleep intervention :)