One small joy of sleep is flipping over the pillow and feeling the relief of the cooler side. But would you pay $400 to experience that relief all the time?

A French start-up called Moona is hoping that the answer is yes. Moona, which launched last week on Kickstarter and delivers in June 2018, has created a “machine learning smart pillow” that can always stay cold (or hot, if you prefer) and learn to adjust to the best temperature. The gadget tries to improve sleep quality by making sure you’re never too hot or cold. But sleep researchers say this high-tech solution might not be necessary for sleep problems. “The idea to use temperature changes to improve sleep is very valid, but the implementation of it is very difficult and I don’t think a cooling pillow would do the job,” says Eus van Someren, a sleep researcher at the Netherlands Institute for Neuroscience. (The company had cited his papers as part of the research that inspired the product.)

Moona co-founders Coline Juin and David Stoikovitch recently visited the Verge offices in New York to give me a demo. Since I couldn’t take the prototype home, I can’t speak for how it would work over an entire night. But it certainly did feel cold and comfortable during the twenty minutes I lay prone on a leather couch, (awkwardly) looking up at Juin and Stoikovitch and asking questions.

The gadget is not exactly a pillow. It’s technically a thick, quilted memory foam pad that you put inside a pillowcase on top of your own pillow. The pad is filled with tubes full of water, and connected by a thick cord to a little white water tank that stays on the bedside table. The water tank heats and cools the water in the pad, and is controlled with either a remote or an app. (The liquid does evaporate, so it’s recommended to refill it with filtered water.) Stoikovitch put the pad under my head on a 12-minute cycle and it went from pleasantly cool — which I like, as I tend to run hot — to slightly warmer.

That’s the “smart” part of it. The app is where the “machine learning” claim comes into play. The pad has a motion sensor on one end to measure your nightly tossing and turning, which is supposed to be a proxy for sleep quality. Based on the data from the sensor, the app over time learns which temperatures and times lead to less movement, and adjusts accordingly. The gadget can also track the room’s light, temperature, and humidity, and you can program it to wake you up with increasing heat under your head in the mornings, instead of relying on an alarm clock.

The co-founders told me that everyone’s sleep is affected by temperature. This is true: our body temperature starts to go down in the early evening, and it reaches its coolest — though it’s still only about 1.8 degrees Fahrenheit cooler than usual — at about four in the morning. This day-night rhythm in body temperature is related to sleep somehow, though sleep scientists are still not sure exactly why. We also don’t know if it’s true that many people naturally can’t regulate their body temperatures at night, according to van Someren.

But when it comes to cooling your body during the night, your head might not be the best place to start. Think about the body’s skin circulatory system like the radiator of a house, says van Someren. When you turn the knob, the radiator opens and dissipates heat to the room. In the evening, our bodies “open” to release heat from the skin, especially in key places like the palms, and the bottoms of the feet. So if you want to adjust your body temperature in bed, your hands and feet are probably more important, says van Someren.

Van Someren has done experiments using brain-monitoring technology. By enclosing participants in a thermal suit, he and his colleagues were able to manipulate temperature by a very small amount, within half a degree. When warming wasn’t stopped in time, it disturbed sleep. Van Someren thinks the only promising solution for sleep improvement would be to constantly monitor the skin at many places on the body and manipulate temperature only when and where it drifts out of the optimal range — either too warm or too cold — for sleep. (That’s obviously hard to do.)

Juin noted that prospective customers for the Moona pillow included menopausal women experiencing hot flashes — but hot flashes happen very quickly and are unstable, says Jamie Marc Zeitzer, a Stanford University sleep researcher. So they may unexpectedly come and then go before you have time to turn your app to slowly adjust the temperature of your pillow.

And what about that app? The sensor in the pad does detect motion, and someone who is tossing and turning is probably not sleeping well. But motion sensors also miss a lot of information, since lots of people sleep badly without moving at all, so the data being collected might not be very relevant.

The truth is, a lot of sleep problems are more psychological, says Zeitzer. A lot of insomnia treatments, for instance, have more to do with changing people’s perception of sleep than it does with changing the quality or amount of sleep. So if the pillow makes you more psychologically comfortable, it can still help. But there are cheaper alternatives: if you run hot, try sleeping with your hands and feet outside the covers. If you run cold, sleep with socks. Not drying off completely after a shower might help cool you down, since our body will then expend heat trying to warm you back up. The temperature of the room, the type of bedding you use, how your partner sleeps, and their preferences all have an effect too. Everyone is different.

So the Moona pillow does what it says. It’ll probably make you a little more comfortable — but so will a lot of other options that don’t cost $400.