Infrared saunas have become so popular that Amazon is selling these bizarre-looking foldable spas that people can take with them anywhere

SereneLife

The SereneLife portable infrared sauna.

• Infrared saunas have gained popularity in recent years, especially as celebrities have increasingly used them for pain and stress release.
• Boutique spas in New York City can charge as much as $70 for a single session, but an increasing number of cheap infrared saunas have cropped up on Amazon.
• They're one of many surprising products Amazon can deliver to your doorstep - along with cheap houses that take just two days to build.
• Visit Business Insider's homepage for more stories.

Infrared saunas have emerged as one of the hottest wellness trends in recent years - and not just because they make you sweat. Celebrities from Lady Gaga to Selena Gomez have used them to relieve pain and release toxins. Boutique spas have cropped up around the country from New York to Los Angeles, where patrons pay around $70 for a single session.

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They've become so popular, in fact, that you can actually purchase one of your own on Amazon. The online retail giant offers a wide variety of infrared saunas on its website, from elaborately built cedar structures that can cost upwards of $2,000 to portable, collapsible saunas that resemble wearable tents and cost less than $200.

This portable infrared home spa from SereneLife, a company that sells everything from mailboxes to trampolines on Amazon, is an example of the latter. The Amazon listing describes it as a portable sauna kit capable of heating up to 140 degrees that you can pack up and take with you. It includes a chair and a heating foot pad, and a zipper on the front that lets you get in and out of the sauna. There are two arm holes on the front as well.

Companies such as Radiant Saunas and Durasage sell very similar products that resemble zip-up tents with just enough room for one person.

Durasage

Durasage's infrared home sauna

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Infrared saunas use light to create heat and warm your body directly rather than heating the air around you like a traditional sauna, according to the Mayo Clinic. While several studies have found health benefits in using infrared saunas to treat chronic conditions, additional studies are necessary to confirm these results, as the Mayo Clinic also notes.

But if you're going to opt for an at-home sauna you've ordered online instead of going to a spa, you should be careful. While SereneLife's product - which Amazon has deemed worthy of the Amazon's Choice badge - has received some positive reviews, at least one recent review indicated that the sauna's electric unit overheated and started producing smoke.

Others, too, have received troubling customer reviews, such as this model from Radiant Saunas. One reviewer said the sauna caught fire after preheating it for the third time, although it has a four-star rating overall based on other positive reviews.

Infrared saunas are just one of several unexpected products Amazon can deliver to your doorstep. The tiny home kits that Amazon sells for a fraction of the price of the average American home- such as this $19,000 cabin kit that takes two days to build and this $37,000 expandable container home - have gone viral in recent months.