Unlike Ernest Hemingway who said, "I love sleep. My life has the tendency to fall apart when I'm awake," today's entrepreneurs can't get anything done when they're unconscious in bed.

For leaders like Apple CEO Tim Cook, who wakes up at a ridiculous 3:45 every morning to get a head start on the 700-800 emails he receives a day, sleep gets in the way of staying on top of their mountainous responsibilities.

While some billionaires are genetically fortunate to require only 3-4 hours of sleep, others force themselves to sleep less, and others sleep the typical 8 hours a night.

Is sleep worth it? For people who run global businesses, should sleep be sacrificed for the sake of being productive?

There's no silver bullet or universal "best sleeping habit" to follow, but by tracing the habits of the ultra-successful, you can more effectively examine what habits you might want to adopt.

The Sleepless Elite

A term coined by the Wall Street Journal, the "Sleepless Elite" are the lucky ones -- people born with the "Thatcher Gene" -- a genetic mutation possessed by 1 percent - 3 percent of the world's population causing them to require less sleep to function normally. While the rest of the world sleeps, they work. While it's unknown who exactly has the Thatcher gene and who doesn't, there are some successful businesspeople who have no problem throwing the eight hours of sleep a night rule out the window.

For example, the recently elected 45th President of the United States, Donald Trump, a 70-year-old billionaire has touted a 3-4 hour sleep schedule for decades. Apple's VP of Retail Angela Ahrendts said she gets a headache if she sleeps more than six hours a night. She wakes up before the sun rises at 4:35am.

Chrysler Fiat CEO Sergio Marchionne gets up at 3:30am to check European markets. His staff claims he has invented an "eighth day" of the week. Pepsico CEO Indra Nooyi studied at Yale while moonlighting as a receptionist from midnight to 5am. She still sleeps 4-5 hours a night.

Marissa Mayer, CEO of Yahoo!, is known to sleep 4 hours a night so that she can allegedly crank out a 130-hour work week. However, in 2014, she missed an important dinner with chief executives due to an overdue nap, after being awake for 20 hours. It's a good reminder that unnatural behavior has its consequences.

The Driven Ascetics

While some founders seem to succeed without a traditional amount of sleep, others try to shave a few hours off of the typical 8 hours per night and hope that they can squeeze by.

SpaceX and Tesla visionary Elon Musk said in an interview that his mental acuity drops at a certain threshold of sleep. He strives for an average of 6-6.5 hours a night.

Sleeping less than 8 hours each night didn't quite work for Huffington Post founder Arianna Huffington, who collapsed from sleep deprivation due to 18-hour work days. Since the incident, she has become an outspoken champion of healthy sleep practices.

Dual CEO of Twitter and Square Jack Dorsey tersely described his morning routine in a Product Hunt AMA: "Up at 5, meditate for 30, 7 minute workout times 3, make coffee, check in. I sleep from 11-5a usually. Blackout shades help. Meditation and exercise!"

Actor Dwayne "The Rock" Johnson frequently posts his 4am workout on social media. He created The Rock Clock, a mobile app alarm clock for his followers to know when he wakes up, usually at 4am, to hit the gym.

The Successful Sleepers

Lastly, there are those who sleep like us, and yet manage to build enormous businesses and rake in millions. These "normal people" don't need the extra time to be hugely successful.

Facebook's darling billionaire Mark Zuckerberg awakes at 8am, sometimes later if he stayed up late chatting with programmers. Zuckerberg is a prime example of making it big without being a morning person.

A strong proponent of the 8-hour circadian rhythm, billionaire Jeff Bezos avoids morning meetings to eat a healthy breakfast with his wife and kids. "I just feel so much better all day long if I've had eight hours," he said.

Microsoft founder and philanthropist Bill Gates emphasizes the importance of at least 7 hours of sleep to be creative. In 1997, he confessed an envy of short sleepers, who had "so much more time to learn, work, and play," but apparently it didn't stop him. (Who knows, maybe he would've run for president with the extra time).

Find the optimal sleep routine for you

Sleep habits vary widely, even with successful business men and women. Less sleep doesn't guarantee more success, and in some cases can do the opposite. More sleep, without good reason, can just be laziness.

Sleep allows you to do what you love when you're awake. If your sleep habits prevent a healthy and balanced lifestyle, it might not be worth forcing an unnatural sleep schedule on your body.

Instead, explore what works best for you and stick to it to get the most out of your waking hours.