The benefits of getting enough sleep are widely known, but do successful (and busy) people like Elon Musk, Richard Branson and Barack Obama actually squeeze in the recommended eight hours?
Some successful people swear by a strict sleep regimen and get to bed early. Others tend to stay up until well past midnight.
Here's how six successful people approach bedtime.
"I actually measured this with my phone," Musk wrote in a Reddit AMA in 2015 when asked how much sleep he gets per night. "Almost exactly six hours on average."
It's been reported that Musk wakes up routinely at 7 a.m. to address "critical emails," so that would mean he hits the pillow at 1 a.m.
Virgin Group CEO and founder Richard Branson might be known for his adventurous attitude, but he has a tame night-time routine, as well as a reasonable bedtime.
In December, Branson revealed in a blog post that post-dinner, he likes to "retreat to a quiet space" with tea for a social media and email sweep, but makes sure to power down his digital devices before hitting the hay.
"If I have some time to spare, I'll read for a bit or perhaps watch a documentary, to help me relax and put me in a great frame of mind to get a good night's sleep," Branson writes. "Then it's in bed and lights out hopefully by 11 p.m. I typically need five to six hours sleep to get the most out of my days."
Former U.S. President Barack Obama is notorious for being a night owl.
He's been known to stay up well past midnight; a 2016 New York Times article reported that he would send out emails late into the night, often past 1 a.m., during his tenure in the White House. He would typically have dinner with his wife and daughters at 6:30 p.m., then head to his private office to spend four or five hours a night there, mainly alone.
"I'll probably read briefing papers or do paperwork or write stuff until about 11:30 p.m., and then I usually have about a half-hour to read before I go to bed, about midnight, 12:30 a.m., sometimes a little later," Obama reportedly told Jon Meacham, the editor in chief of Newsweek, in 2009.
Ellevest co-founder and CEO Sallie Krawcheck previously revealed that she heads to bed early so that she can wake up even before the crack of dawn, which she says is the best time to get work done.
"[T]his does mean I have to go to sleep earlier, but I long ago recognized that I am out of gas by about 8 p.m. every evening," Krawcheck wrote in 2014 on LinkedIn. "Any work that I try to do after that isn't up to my standards anyway, so I give myself a break then. I use that time to be with my children, to socialize ... and to get to sleep so that I can start again at 4 a.m."
Oprah Winfrey might lead a busy, busy life, but the actress, producer and philanthropist is still able to adhere to a healthy sleep schedule. Winfrey told the Hollywood Reporter in 2017 that she's usually in bed by 10 p.m. and wakes up naturally around 6 a.m.
And, in typical Winfrey-fashion, her night-time routine includes a little self-reflection.
"I usually get into bed and I have volumes and volumes of gratitude journals by the side of my bed," Winfrey tells the Hollywood Reporter. "The last thing I do before I go to sleep is write five things that gave me great pleasure or that I was grateful for."
Media mogul Arianna Huffington prioritizes sleep; she's even penned a book on the topic. She says that 95 percent of the time she gets eight hours a night.
"Most nights I'm in bed by 11:00 p.m., and my goal, as we joke in my family, is to always be in bed to catch the 'midnight train,'" Huffington has said.
She started taking sleep more seriously after fainting at her desk in 2007 from sleep deprivation and exhaustion, breaking her cheekbone in the process.
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