No snooze? You lose!

LeBron James sleeps half his life away. So does Michelle Wie. And look where it's gotten them: both are powerhouses. On and off the field, Forbes ranked James as the second most influential athlete last year (behind Lance Armstrong), and in '06, Time magazine named Wie as one of the 100 people who shape our world. Those hours in dreamland are clearly well spent, and just might be their, and many other top athletes' (who routinely get a minimum of 8 hours of sleep a night) secret to success. Studies show a solid night of shuteye can make you faster and stronger, while skimping on sleep makes you slower, wimpier, and more likely to end up benched with an injury. We talked to some of the leading sleep experts for the stats on how a healthy dose of pillow time can keep your eyes wide and locked on the prize.

Build muscle overnight. No matter how hard you work out, that 5 a.m. alarm may be stunting your strength. Why? Because your body pumps out 80 percent of your human growth hormone (HGH) during deep sleep. HGH is a naturally occurring hormone that increases muscle mass and strengthens bones. It's such a potent performance enhancer that synthetic versions had to be banned by the International Olympic Committee, and are hunted by the anti-doping police. This muscle-building elixir is released during the deepest levels of sleep -- specifically, the ones you nix when you stay up too late, get up too early, or do both, said sleep researcher Peter Walters, Ph.D., a professor at Wheaton College. That's bad news for 40 percent of adults who average less than seven hours a sleep a night, according to the National Sleep Foundation. Maximize those gym sessions with an earlier bedtime, a later wake-up call, or both.

Kick start your sprint speed in your sleep. Whether you're sprinting down the soccer field, racing a 10K, or doing the butterfly across the pool, well-rested legs will carry you further faster. In a series of studies done with NCAA athletes, Stanford University sleep researcher Cheri Mah found that sleep extension -- sleeping a couple hours longer than normal in order to pay back the "sleep debt" you accrue by sleeping too little most nights -- yielded faster times on sprint drills, from swimming to tennis to basketball. In fact, well-slept female athletes enjoyed an eight percent increase in sprint speed. On the flip side, sleep deprivation slows you down. British researchers found that runners ran up to nine percent slower after they've stayed up all night. They even used more oxygen (meaning their bodies were working harder) than usual while they tried to run a steady pace. Hardly the recipe for a PR.

Sharpen your reflexes as you snooze. Sleep deprivation research shows that a lack of sleep deteriorates decision-making and reaction time, while a healthy dose of sleep improves it. Tennis players who slept 10 hours a night improved their hitting accuracy by 42 percent. Though the lion's share of reaction-time sleep studies are designed to examine more life-and-death matters, such as driving safety, in sports, even a split-second lapse in judgment could mean giving up a goal, getting passed at the line, or worst of all, landing wrong from a jump and blowing out your ACL.

Lock in new skills. Your body's muscles aren't the only ones getting stronger while you sleep. Your brain is hard at work, too, organizing and categorizing everything you've learned over the day. Harvard Medical School researchers found that people improved their speed and accuracy on finger tapping tests (where you learn and repeat finger tapping patterns during a timed test) by 20 percent and 39 percent, respectively, after a night's sleep, versus seeing zero improvement without sleep. These tests measure how quickly you can consolidate and cement new skills. So if you've been practicing ball handling drills, learning plays, or even perfecting your free throw, honing this process can help to cut down on mistakes and increase your speed of execution. Those final hours of a good night's sleep are crucial here: getting more stage two, non-REM sleep (which happens late in the night, or right when your alarm goes off if you stayed up too late) was also linked to improved morning-after performances.