Why do hockey players take pregame naps? It’s a tradition with many idiosyncrasies.

Kirill Kaprizov used to get on the Wild plane and go to sleep.

As a rookie fresh from Russia, he would be out like a light while teammates played cards, and how much the newcomer was nodding off didn’t go unnoticed.

“Guys asking me like, ‘How do you fall asleep right away?’” Kaprizov recalled.

Now, in his sixth NHL season, Kaprizov stays awake and has joined the card game.

But the Wild superstar is still catching Zs.

“I’m nap guy,” he said.

Like babies and those who siesta, hockey players take afternoon naps.

“Sometimes 20 minutes and just boom,” he said. “Like new.”

Sleep, like the opponents he overwhelms on the ice with his skill, is apparently no match for Kaprizov.

Aside from being able to drift off at the drop of a hat, brightness doesn’t keep him up. Neither does caffeine.

“I can drink coffee before bed and sleep right away,” the Wild’s leading scorer said. “I don’t care. Nothing changes for me. I don’t feel nothing.”

Shuteye, though, isn’t the enemy. It’s an ally, and the Wild are sleeping on the job to do the job.

The tradition of the pregame nap tends to begin before the NHL, when players are younger — but not stopping by the snack bar in the rink and loading up on candy and Gatorade.

Many add naps in junior hockey or once they play games at night.

“It’s more to reset the day,” goaltender Filip Gustavsson said.

Matt Boldy was with USA Hockey’s National Team Development Program and Vladimir Tarasenko was a 16-year-old in the KHL in Russia when they started napping — Tarasenko napped because the older players did. Kaprizov also started because everyone else on his Russian junior team was doing it, and he discovered a passion.

“I just love naps,” he said.

“You’re just trying to survive, and you’re still growing,” said Foligno, 34 and the father of three. “So, I feel like you have to sleep. I would go two hours, and now I’m down to like maybe 45 minutes to an hour.”

Spurgeon has also cut back from a few hours to 30-45 minutes.

“As you get older, I think it gets a little harder to nap for longer,” the defenseman said.

Even a cat nap is restful.

“You get a good 45 minutes to an hour,” Foligno said, “and that’s all my body needs. You just feel good coming out of it. It’s quicker, but it’s right to the point. Maybe you’re mentally not as groggy because you know what to expect in this league.”

“I don’t have any kids or anything like that,” he said. “I got no responsibilities. I just sleep as long as I can.”

Joel Eriksson Ek never misses naptime, which lasts a couple of hours.

“With how much you travel and how much you play and with a lot of late nights,” he said, “it’s a good way to catch up on some sleep.”

The players aren’t the only practitioners.

“You want to be mentally sharp and have energy for the game that night, too,” Wild coach John Hynes said. “So, most coaches nap.”

“If I sleep for 30 minutes or if I sleep for an hour, two hours,” Brock Faber said, “it doesn’t matter.”

On a Sunday, Ryan Hartman might put on a football game during the downtime; Mats Zuccarello only dozes off when he feels like he needs to; and goalie Jesper Wallstedt doesn’t nap at all.

“I feel like if I sleep at night enough, I shouldn’t have to sleep during the day,” the rookie netminder said. “… I just don’t get tired during the day.”

Gustavsson naps for the opposite reason.

“Because I’m tired,” he said.

“If I had earplugs,” Wallstedt said, “I’d be scared I would not wake up.”

A father of two, Gustavsson hasn’t had that problem — not when “you have a kid coming jumping on you.”

Tarasenko, who would log 3½ hours ahead of late-night puck drops in the playoffs, doesn’t want to feel like he has to rush to fall asleep, so he will read a book beforehand.

“I never [hit] snooze,” he said. “If I snooze, I’ll sleep in, for sure.”

Foligno’s ideal temperature in the room is 68 or 69 degrees Fahrenheit.

Before the Nov. 28 home game vs. Colorado, which started at 2:30 p.m., Kaprizov didn’t nap, and he had two goals in a 3-2 shootout victory for the Wild.

“I feel great in the game,” he said. “Legs feel good. Body feel good. I’m like, ‘Oh, I don’t know, maybe I don’t need any sleep.’”

Wild players are encouraged to do what feels best for their bodies, but any extra sleep is beneficial, especially considering how much they exercise and their schedule, which is in flux due to games and travel.

“That’s when everything recharges and gets better, is when you’re sleeping,” said Wild head strength and conditioning coach Matt Harder, who pinpointed six to nine hours as the optimal range for nighttime. “Everything we do improves during the sleep. So, if we can sleep more or sleep better or have higher-quality sleep, even if it’s shorter-duration sleep, then great.”

The team doesn’t track sleeping habits, but some players have an Oura Ring that gives them their data.

The device monitors his calories, steps and blood oxygen level, but what Sturm pays attention to most is his sleep, which he has prioritized this season.

“It analyzes the quality of the sleep,” the forward said. “Tells you, hey, you might have been in bed for eight, nine hours, but you only got 45 minutes of regenerative sleep. You were not in deeper REM sleep. Those are the two important phases you try to get into.”

Sturm missed the first six weeks of the season because of a back injury. While he was recovering, he believes he had the healthiest sleep of his life: He was falling asleep at 9:30 p.m. and waking up at 6:30 or 7 a.m.

“You can feel how your brain clears up and how crisp and clear your thoughts are,” Sturm said. “You don’t drag yourself out of bed.”

This rhythm was interrupted by his return, and Sturm struggled to fall asleep during his first few pregame naps.

“The last couple years, I was very, very sensitive,” said Sturm, who will play for Germany in the Olympics. “It had to be a totally dark and quiet room. I could not stand the sound of white noise or A/C or anything like that.

”So, actually, last couple years I slept with a mask and foam earplugs. I’ve now been more accustomed to white noise. The darkness I still need, so I need the sleep mask, and temperature, I’m like around a 68.”

After games, Sturm wears blue light glasses and tries not to scroll Instagram. He and Tyler Pitlick do crossword puzzles on the plane. During the bus ride to the hotel, Sturm will take magnesium.

“If there’s a stretch where you play a lot of hockey,” Sturm said, “you have a lot of pregame skates, it’s like you can’t wait after pregame meal to be in bed, and you’re just lights out.”

As advantageous as sleep is, the nap is also appealing because it’s part of a routine, and players like knowing what’s going to happen.

“Everything is just off of what happens. But during the season, every day it’s either a practice, a day off or a gameday, and it’s over and over and over.”

Even though he’s not napping, the Swedish Olympian has a plan for the afternoons before games, lounging in massage pants while making saves with virtual reality controllers.

Gustavsson, also on the Swedish Olympic team, downs a Monster energy drink before the game, and Foligno sips black coffee with maple syrup. Sturm has his coffee during the pregame meetings.

“I don’t need to have it right after my nap to get going because it’s still 3½ hours till game time,” Sturm explained. “So, I don’t want to have that crash.”

Hartman has heard of drinking an espresso shot before a nap so that it kicks in just as someone is waking up, what’s referred to as a nappuccino.

Instead, Hartman has a Red Bull in between periods.

“Doesn’t help with the night sleep, that’s for sure,” he said.

But caffeine in-game is popular to ward off fatigue, especially Coca-Cola.

That’s right: Professional athletes are gulping sugary soda at intermission.

“Just a splash, yeah,” said Boldy, who was shown on a game broadcast pouring a can of Coke into cups inside the Wild locker room earlier this season. “Just to pick you up.”

But first they have to wake up from their nap.