(CNN) - The gentle rustle of leaves. Raindrops softly tapping on the window. John McEnroe describing the maximum permitted length and width of a regulation tennis racket, as per Appendix II of the International Tennis Federation rulebook.
Certain sounds just scream "relaxation."
And now, that final option is available to lull you to sleep, or take a weight off your shoulders after a stressful day.
McEnroe, the legendary American tennis star known for his aggressive on-court demeanor and his famous four-word catchphrase, has released an audio recording of tennis rules intended to help listeners drift off. And yes, we're serious.
"Before we begin, take a moment to sit back and relax, letting your eyes fall gently closed," instructs the ex-pro, known for his frequent racket-breaking outbursts and profane rants at officials. "Picture yourself resting on a comfy grass court, as the summer breeze drifts by and birds call out in the distance," he adds.
The audiobook that no-one asked for was released Thursday on the popular Calm app, which hosts a number of "Sleep Stories" -- recordings and songs designed to aid mindfulness and relaxation.
It features McEnroe going in-depth on scoring conventions, equipment regulations and everything else you ever wanted to hear about the sport.
And it's quite the undertaking -- the most recent ITF rulebook is 45 pages long, with 31 sections and 11 appendixes.
"I love the game of tennis. I'm just a stickler for rules and making sure they're applied accurately," McEnroe explains on the recording, which is titled "But seriously, the rules of tennis."
"It's no secret that I can get a little riled up about the game on occasion, which usually ended with me speaking my mind to an umpire or two. I mean, they cannot be serious," he adds in his trademark dulcet tones.
"This Sleep Story is designed not just to soothe the restless souls of tennis fans, but also to remind us all the tennis rules you may have forgotten or never knew."
McEnroe won three Wimbledon titles and four US Open crowns during his lengthy playing career, before working as a television analyst on British and US television.
While his move into relaxation tapes seems unlikely, he isn't the first celebrity to try his hand at sending listeners into an unconscious state.
Matthew McConaughey became Calm's highest-profile acquisition, joining other celebrities such as actor Stephen Fry in reading a Sleep Story for the service.
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