During his early days at Microsoft, Bill Gates would pull all-nighters, sometimes multiple nights in a row, to finish projects or meet deadlines.

Gates recently shared his favorite books of 2019. The list was an eclectic mix of fiction and nonfiction books, including one title that he said put him to sleep — in a good way.

“Why We Sleep” is a book written by Matthew Walker, a sleep expert and the director of University of California Berkeley’s Center for Human Sleep Science. Gates wrote that reading the book made him re-think his own sleep practices.

“Walker taught me a lot about this basic activity that every person on Earth needs,” Gates wrote on his blog. In fact, Gates used to think very differently about sleep.

Get the full story at cnbc.com.