The great sleep researcher Casey Stengel (okay, not really: he's best known as the wise-cracking manager of the Yankees in the 1950s) once quipped, "it's not sex that wrecks these guys, it's staying up all night looking for it." Regardless of how you spend your nighttime hours, are you setting yourself up for failure if you lose sleep before a big event? The answer, shown by studies of Olympic lifters, Judo competitors, and elite motocross drivers, might surprise you.

When you're strongest

A study of collegiate weightlifters, published in the Journal of Strength and Conditioning Research in 2007, showed that they did just as well on the snatch, clean and jerk, and front squat even after a night of missed sleep as they did after a normal night. Well, there's our answer. We can go home. (Please don't go home. This gets super interesting.)

Those guys were tested in the morning, and it turns out the time of day counts. In a study done this year in Tunisia, Judo competitors were studied in both the morning and evening, and after a normal night of sleep they did better on tests of power and strength in their evening session. That's a common finding in time-of-day studies--so, if you have a choice of when to compete and sleep isn't an issue, choose the afternoon.

After partial sleep deprivation, though, the judokas' morning performance was fine but degraded in the afternoon. The researchers also tested whether it mattered when they missed sleep. Staying up late led to better results than waking up early, even though the total amount of sleep was the same.

Maybe you've heard the advice that one bad night of sleep is no biggie, but two or more is what does you in. (As you can see above, that would apply to morning competitions.) So one would expect that on the second day, performance will be crappy to match. Getting back to weightlifting, let's look at multiple nights of inadequate sleep. This 2007 study from Liverpool doesn't say whether the subjects were trained lifters, but their strength was tested in the evening after an all-nighter with a biceps curl, bench press, leg press, and deadlift. After the first night, their 1-rep max was the same as usual, but submaximal performance was already going downhill. The second and third nights, of course, were worse on all counts.

How about aerobic performance?

Cardio fares a little better, but with some caveats. After a single night of partial sleep deprivation, Taekwondo practitioners did fine on a running test that put numbers on their heart rate, lactate, and perceived exertion. In a 2009 treadmill study (where 11 subjects were tested in the afternoon after a total all-nighter), runners said they felt fine, but couldn't cover as much ground.

But there's more to an athletic performance than strength and cardio. What if you need accuracy in your movements (and really, who doesn't)? One French study from 2012 examined elite motocross racers, who often need to stay up fixing their bike during multi-day competitions. Their ability to balance and control their bodies degraded after they lost sleep, a finding that's been repeated in studies of various types of athletes.

Can caffeine help?

Results on this are mixed. Tennis players asked to serve balls into a tiny area found their accuracy degraded after missed sleep in a Sleep Research Centre study from earlier this year, even though their strength was at normal levels. Even an 80-mg shot of caffeine (the same as a can of Red Bull or a weak cup of coffee) didn't counteract the effect.

On the other hand, a study done in the UK of ten elite rugby players found that accuracy in repetitive passing drills could be restored with either caffeine or creatine.

And finally, a study of military snipers who'd been denied three nights of sleep found that their accuracy degraded – not surprising. Done during Navy SEALs' grueling "Hell Week" of training, snipers who took 200+ mg of caffeine were able to find the target and shoot faster, but their accuracy wasn't any better than their peers on decaf. (It also wasn't worse, meaning no significant jitters.)

The caffeine question is a tough one because although doses are standardized in the studies, but caffeine tolerance can vary from person to person; it has less of an effect on somebody who chugs Starbucks every morning than it does on people who (I swear I have met people like this) avoid chocolate chip cookies because of the caffeine in the chocolate chips.

Okay, okay, I'll sleep already

Let's put a positive spin on this. If you sleep more than you need to, will you do better? There's evidence that points to yes. When basketball players were made to spend 10 hours in bed each night, as part of a Stanford sleep clinic study, they had better sprint times, shooting accuracy, and reaction time. Their mood even improved (which a lot of the above studies mentioned too – lose sleep and you'll be cranky.)

Bottom line

Sleep is good, but you can get away with little to no sleep before a morning competition. Your performance will start to degrade by afternoon, and definitely by the next day. Caffeine may help in a pinch, but don't count on it to stand in for lost sleep. And if you have to miss sleep, say to travel, it's better to stay up late and crash in the morning, than to start your journey in the wee hours.