Michael Phelps, the most decorated Olympian of all time, shared a secret to his athletic success that even us mere mortals can steal: a solid eight hours of sleep.

The swimmer spoke to CNBC about his lifelong dedication to getting great sleep and how it’s been a priority for him since he was young. The Olympian, who recently partnered with mattress company Leesa, said, “I really can’t say it enough. I don’t think people pay enough attention to how important sleep is.”

To train for the Olympics, Phelps swam seven days a week, logging between 70,000 and 100,000 yards a week. Out of the pool, Phelps would try to get around eight hours of sleep a night and would also take a 2 to 3 hour afternoon nap.

Phelps also tracked his sleep habits, monitoring quantity, quality and whether he was getting REM sleep, deep sleep or light sleep, according to CNBC. Phelps is one of many professional athletes who say a good night’s rest is an essential part of their game plan, including other champions like Tom Brady and Lebron James. And here we were thinking Phelps’s secret weapon was his massive, and well-documented, daily diet.

Read more about Phelps’s CNBC interview here.

Originally published at journal.thriveglobal.com