Whether it's World Series baseball, Bowl Championship Series football or the high school district championship, does victory belong to the well rested?
There's certainly plenty of recent research that points to sleep giving players competitive advantage in athletics.
A series of studies of swimmers, tennis players, football players and basketball players at Stanford University over several years showed that athletes who extended their normal sleep time to eight to 10 hours a night substantially boosted performance.
They ran or swam faster and basketball players bumped up their accuracy on both free throws and three-pointers by about 9 percent. The players also had faster reaction times and improved moods.
Researchers think extra sleep helps athletes in several ways: by improving brain function, reducing stress and releasing more growth hormone that promotes healing of muscle and bone.
Of course, not getting enough sleep is just as likely to bring you down.
Studies at the University of Chicago more than a decade ago showed that as little as one week of sleep deprivation in otherwise healthy young men reduced their ability to metabolize glucose by 30 to 40 percent. They also had higher levels of the stress hormone cortisol in their blood, which inhibits muscle recovery.
Other research has shown being short on sleep cuts aerobic endurance and makes people feel as though their bodies are working harder.
A pair of studies, reported during a meeting of sleep experts this summer, noted that National Football League and Major League Baseball players who report experiencing more daytime sleepiness are more likely to get cut or retire early than other players.
The studies relied on surveys of pro players done by Dr. Christopher Winter, a specialist at the Martha Jefferson Hospital Sleep Medicine Center in Charlottesville, Va., and his colleagues.
The football study involved 55 randomly selected college players drafted into the NFL. Sleep questionnaires showed that the sleepier athletes had only a 38 percent chance of staying with the team that first drafted them, compared to 56 percent of the less sleepy players.
The baseball study looked at the sleepiness ratings of 40 randomly selected players and found that the sleepiest had attrition rates of 57 percent to 86 percent, much higher than the average MLB rate of 30 to 35 percent.
Winter noted that teams might use sleepiness assessments in making draft selections, but could also use them to better address performance issues and prolong careers.
Getting adequate sleep also reduces odds for athletic injuries, at least among teens, according to a study presented at the American Academy of Pediatrics annual meeting in New Orleans Oct. 21.
A study of 112 student-athletes at a private California middle school and high school found those who slept eight or more hours each night were 68 percent less likely to be injured in practice or play.
The surveys at the Harvard-Westlake School in Studio City asked students in grades 7 to 12 (and ages 12 to18) about the number of sports they played, the time they devoted to athletics, whether they did strength training, how much sleep they got each night and how much they enjoyed athletics. Fifty-eight of the respondents were female, 54 male.
Nearly 77 percent of the students said they were getting less than eight hours of sleep a night. The Centers for Disease Control and Prevention estimates that about 69 percent of high school students nationwide sleep less than eight hours a night.
Over a 21-month period, 56 percent of the athletes sustained an injury that was reported to school athletic trainers and 38 percent sustained multiple injuries.
The factors most closely related to injury were hours of sleep, followed by the athlete's year in school (freshman, sophomore, etc.). Risk of injury rose 2.3 times with each higher level. Researchers said that might reflect the cumulative risk of injury after playing a sport for three or four years and noted that older athletes are bigger and stronger.
(Contact Scripps health and science writer Lee Bowman at BowmanL@shns.com .)