When my recurring knee and lower back pain led me to a physical therapist, I was surprised that they prescribed a set of glute-strengthening exercises.

I’m an avid runner and enjoy lower-body workouts, so I had assumed my glutes were doing their job, but I was wrong.

I’d never heard of pickleball until very recently, which is surprising considering it’s one of the fastest-growing sports in the world. When asking others about it, I would mostly get a look of confusion, before they said something along the lines of ‘I think it’s like a mixture of tennis and badminton’.

Not known for my skills in either sport, I wasn’t convinced. But a recent trip to Sandals South Coast in Jamaica presented me with 12 pickleball courts, a top pickleball coach, gorgeous weather to play in and lots of free time, so I gave it a go. And I was sold after the first session.

There are some logical things we know to be true: working out is tiring. And being tired helps you fall asleep. But exercise before bed can sometimes have the opposite effect. I have personal experience with this: At one point I was attending a kickboxing class after work at least two nights a week. They were the kind of sessions where you were gasping, willing the seconds to tick by so you could stop and rest. I was all showered and changed by 8:30 p.m. and tucked into bed by 11:30 p.m., where I’d lie wide awake, humming with unwanted energy.

The relationship between exercise and sleep is a complicated one, so I consulted experts to see what they have to say about the best time to exercise before bed. Professor Kevin Morgan founded the Loughborough University Clinical Sleep Research Unit 20 years ago and has made sleep the focus of his work. He says many elite athletes are not experiencing the deep slumber you would imagine.

“Athletes sleep badly, elite athletes sleep worst of all, their bodies ache, their muscles twitch, they’re kind of wired people anyway,” Morgan says. “The route to good sleep is not to train like an elite athlete.”

The guidance around when to exercise before bed depends on two factors; the intensity and regularity of your workout. Professor Morgan confirms my post martial-arts insomnia was not unusual: exercises destroy your ability to doze off.

“Absolutely intense levels of activity are not the path to great sleep,” Morgan says. “It’s not uncommon for people with chronic insomnia who say ‘I’ve tried everything’ to include in ‘everything’ intense activity. The relationship between sleep and exercise is not linear.”

Morgan says the research about when to exercise has shifted slightly. The rule has traditionally been to avoid exerting yourself for three hours before attempting sleep, but now it’s thought more gentle activity can be carried out much later.

“If you’re a serious runner and you’re going to do 10K, you’re best not doing it an hour before you go to bed,” says Morgan. “It will take that long for your body to cool down—but something more modest will not do you any harm.”