The Rumor: We can get by on only a few hours sleep per night

In America, we love us some overachievers, so when a rumor surfaces that some people (like President Obama, Madonna and Yahoo CEO Marissa Mayer) get by on four hours of sleep a night, we start to question our own need for shut-eye. Four hours… really? That's a lot of extra hours. We could accomplish so much more if we only slept half as much!   

But will cutting down on shut-eye like the "sleep elite" make you a more perfect human or just a miserable creature? We took a look at the latest research and interviewed sleep experts to find out how much shut-eye we really need.

The Verdict: We need sleep – lots of it

Simply put, we need our Z's, and most us could use more, not less, of them. Consider this: Research from the National Sleep Foundation -- a 2013 cross-cultural study looking at six different countries’ sleep habits -- found that the US and Japan were in close competition for the country whose inhabitants get the least amount of sleep. The average American, the survey found, sleeps just six hours and 31 minutes per night, with the Japanese clocking just nine fewer minutes. 

Meanwhile, "People do best when they get seven to eight hours of sleep," says Robert Rosenberg, DO, FCCP and Director of the Sleep Disorders Centers of Prescott Valley and Flagstaff, Ariz. "Sure, some people we call ‘long sleepers’ need nine hours and some people can function on 6.5 hours, but when you get less, you get cognitive problems, trouble focusing and concentrating." Furthermore, taking night-owl tendencies to extremes can lead to both depression and anxiety, according to Rosenberg.

"When you go to sleep, your parasympathetic nervous system (PNS) takes over," Rosenberg explains. "Your heart rate drops, your blood pressure plunges an average of 10 to 15 points. And if you deprive yourself of that time, you’re losing one to two hours when your body would’ve been in a restorative state."

On the other hand, if you stay awake, your sympathetic nervous system -- or "fight or flight" tendencies -- takes the wheel. And that can work against you over time: "An hour or two without sleep a night can add up to 60 hours without shut-eye per month. You can see where that starts to add up," says Rosenberg. "You need sleep in many respects to restore and take the stress off our vital organs."

If your inner insomniac is nodding furiously, you may want to back away from your TV, iPad or smartphone. According to the National Sleep Foundation survey, 2/3 of people in every country studied watch TV in the hour before bed.

What’s so bad about that, you might wonder? Well, it turns out the blue lights that power many of our electronic screens today -- because they boost attention, reaction times and mood during the day -- have a particularly harmful effect when it’s time for us to power down at night.

While exposure to any light at night suppresses melatonin, the hormone which regulates our sleep cycles, a recent Harvard study found that 6.5 hours of exposure to blue light, as opposed to green light (which has a different wavelength), suppressed melatonin for twice as long and shifted circadian rhythms by twice as much.

The idea that we don’t need that much sleep is a myth -- and a dangerous one, at that. "Burn the candle at both ends, and it won’t have any consequences, but in the average person it does," says Rosenberg. So unless you’re Madonna (quick: are you dating your back-up dancer?), you’re better off not depriving yourself.

In short, the list of bad things brought on by no sleep is rather exhaustive, so next time you’re exhausted? Hit the hay.