Trump's doctor says he only sleeps 4-5 hours each night!

Following President Donald Trump's annual physical exam, his physician told reporters on Tuesday that the president only sleeps four to five hours a night.

"He’s just one of those people, I think, that just does not require a lot of sleep," Dr. Ronny Jackson said.

It's something Trump has discussed before — while on the campaign trail, Trump said, "You know, I’m not a big sleeper. I like three hours, four hours, I toss, I turn, I beep-de-beep, I want to find out what’s going on."

Trump's not the only one who sleeps less than average. Corporate executives like PepsiCo CEO Indra Nooyi and even former President Barack Obama rarely — if ever — get what's considered a full night of sleep.

For many of us, getting too little sleep can have some nasty consequences such as headaches and stomach problems. But others are able to thrive off of just four to six hours of shut-eye, something called "short sleeping."

Short sleepers, a group The Wall Street Journal once called the "sleepless elite," need only a short amount of sleep every night instead of the average seven to eight hours. Scientists estimate those individuals make up only about 1% of the population.

It is not known whether Trump falls into this group. But there are a few characteristics that most of the short sleepers that have been identified thus far appear to have:

They tend to be more optimistic and upbeat than most people.
They tend to wake up early, even on vacation or weekends.
They tend to have a family member that is also a short sleeper. Since short-sleeping is linked to genetics, the behavior that accompanies it often runs in the family.
They tend to be physically active.
If they sleep longer than they need, they tend to feel groggy.
They say they tend to avoid caffeine or don't need it to feel energized.
This sleeping behavior is still a relatively new area of study, so a lot is unknown about short sleepers and their genetics. Having some of these traits doesn't necessarily mean you're a short sleeper, nor does not having some of these traits mean you're not.