Tim Cook, the C.E.O. of Apple , rises a little before 4 a.m. every day . President Trump wrote in his 2004 book that he only needs four hours of sleep a night. David Cush, the former Virgin America C.E.O., has said that he wakes up at 4:15. And Jennifer Aniston wakes up at around 4:30 to meditate, as does Kris Jenner, the same time that Michelle Obama is hitting the gym.

Recently, Steve Harvey declared: “Rich people don’t sleep eight hours a day.”

Is the key to success emulating high-profile achievers who are hacking their bodies to increase productivity? Even if capitalism favors early wake-up times, at least as a badge of honor, there is no data that shows that successful people get less sleep.

Americans sleep, on average, less than seven hours a night, which means that many of us get less sleep than the American Academy of Sleep Medicine recommends.

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“This trend goes back a fair bit further than our recent tech C.E.O.s,” said Douglas B. Kirsch, a neurologist and the president of the American Academy of Sleep Medicine. “Thomas Edison used to say the same thing: Four hours are good enough for me. What he left out of the picture is he was a pretty prolific napper as well.”