If you’ve entered the sleep tags of TikTok, you’ve likely seen videos about the pain-relieving, better-sleep-inducing, otherwise magical effects of water pillows. The #waterpillow hashtag has racked up over 25 million views and water pillows are often featured on posters’ “Amazon Favorites” videos as a beloved purchase.

As the name states, a water pillow is like a 1980s-style water bed, but for your head. They’re typically comprised of either a fiber or memory foam topper and an adjustable water pouch at the base. They come with a twist-in funnel for refills, along with a leakproof lid, and can be filled to a user’s desired volume.

While water pillows have racked up a cult-like internet following, there’s not a ton of clinical data on them, said Andrew Vovnoboy, a physical therapist at Precision Care Medical & Sports in Brooklyn. Mediflow, one of the biggest water pillow brands, states their product is “clinically proven,” citing a study conducted on 46 people in 1997.

“We don’t really have any long-term research on it,” Vovnoboy told HuffPost. “I can see how it could work — if you add more water to it, it’s a little bit harder. If you empty water, it’s looser. It probably adjusts more to your personal needs.”

Vovnoboy said that because bodies are so unique, what works for one person is going to be different than what works for someone else. That said, he suggested giving a water pillow a go if you’ve tried other types of pillows and still deal with a stiff neck or have trouble sleeping.

“It’s worth a shot, especially if they’re not crazy expensive,” he said. “Worst case scenario, you don’t really get a good night’s sleep after, you wake up a little grouchy.”

Jono Taves, a physical therapist at Novera: Headache Center in Colorado Springs, Colorado, and host of the “The Headache Doctor Podcast,” said that finding the right pillow for you mainly has to do with your sleeping position. According to Taves, different types of sleepers need different types of pillows: Back sleepers need a thin pillow, side sleepers need a thick pillow, and stomach sleepers ideally want something that will encourage them to stay on their side and give them extra support.

“Depending on your position is and what the water pillow could accomplish, it could potentially be helpful,” Taves told HuffPost. “Most side sleepers are kind of side-to-stomach sleepers, and so it’s important for side sleeping to have a pillow that accounts for the width of your shoulders.”

If you’re interested in trying a water pillow for yourself, we’ve rounded up the three most popular options.

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One last note: Vovnoboy and Taves emphasize that if you’ve been in chronic pain or have lots of tension in your neck or back, you’ll want to see a physical therapist or trained medical professional.

“You definitely want to figure out the cause of the neck stiffness, neck pain back pain,” Vovnoboy said. “The PT will figure it out, and then we can kind of adjust the plan of care accordingly.”

Dan Ginader, a physical therapist at Tx:Team in Indianapolis, also stressed that while a saggy, old pillow may exacerbate existing neck and back issues, a pillow itself is not enough to completely resolve the underlying causes of pain.

“For the most part, body parts get tight and in pain because they are too immobile or too weak,” Ginader told HuffPost. “If pain comes on while doing something static, like working at a desk, it means more movement needs to be done during the day. Something as simple as neck stretches or shoulder rolls a few times a day to break up that static posture can make a huge difference.”