Exactly how much sleep Indra Nooyi, Jack Dorsey, and other successful business leaders get

For most of us, even 24 hours in a day aren't enough to get things done. However, even business tycoons can't change the world clock. The significance of a good night's sleep has been stressed on enough in the past. We have been hearing the importance of getting eight hours of sleep since we were in school. However, billionaires have a long list of things to accomplish every day and they just can't afford to waste a quarter of each day snoozing in bed. While most of them get by on barely any sleep, others are more particular about the number of hours they rest. Here's how much sleep these successful people get:

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Sergio Marchionne, CEO of Fiat

Marchionne went on to become one of the most distinguished executives in the automotive world after he played an important role in the resurrection of Chrysler and Fiat's turnaround. He has gone on to state that he maintained a punishing schedule to achieve what he did. This involved working day in and day out on just four hours of sleep and staying awake with the help of caffeine and cigarettes.

Jack Dorsey, Twitter Founder and CEO of Square

Jack Dorsey will tell you that helming two exciting tech startups doesn't leave too much time to catch up on lost sleep. In 2011, Dorsey told Kara Swisher that he spent eight to 10 hours each day at Square and the same amount of hours at Twitter. This obviously meant that he was left with four to six hours to catch up on sleep, or even less when travel time was factored in. Despite his tight schedule, he woke up at 5.30 am every day to take a jog.

Indra Nooyi, CEO and Chairman of PepsiCo

Nooyi sleeps barely four hours every night since she was promoted to Pepsi's top job in 2007. One of the world's most esteemed female executives says she's no stranger to long hours as she once worked the graveyard shift as a receptionist while getting her Master's at Yale University.

Tom Ford, Fashion designer and director

Under Ford's leadership, Gucci's value increased by 90 percent after this sought-after fashion label employed him as their design director. He strongly believes that his success has more to do with his energy levels and less to do with his talent. That's saying something because Ford once said that he gets by on only three hours of sleep every day.

Barack Obama, Former President of the United States of America

The list would be incomplete without this stellar individual. According to Michael Lewis' profile in Vanity Fair, the President went to bed at 1 am and rose at 7 am, meaning he got by on six hours of sleep each day. Sometimes he got even less sleep when his closest aides in the White House decided that it was alright to wake him in face of a crisis situation.

No matter how many tasks you have to complete, it is crucial to maintain a healthy bed-time routine if you want to get the maximum out of your day. Heed your own needs instead of copying others to become successful on your own terms.