There are dozens of LED hair-growth gadgets on the market, ranging from a $50 product on AliExpress that’s been shopped onto a model to comically bad effect to the $2,500 Capillus Spectrum, which boasts an aggressive array of laser diodes. Contrary to what I would have suspected, women are actually the current dominant consumer group for LED hair-regrowth therapy. As it was explained to me, women are accustomed to spending money on their appearance, and thinning hair is often experienced as a crisis. Men, on the other hand, tend to take the path I did and buzz it all off, then go about their day.

Photograph: Martin Cizmar

I agreed to test the FDA-cleared GroWell, which sits in the middle of the price range at $550. It contains a total of 63 diodes, including 24 lasers and 39 LEDs. Beyond its attractive price point, comfortably between sketchy drop shippers and well-marketed products that cost nearly as much as the top-end MacBook Pro, the GroWell stands out for offering treatment at a level supported by clinical research without an overkill approach that can be counterproductive.

Also, unlike the helmet-style caps on the market, it’s an insert attached to a control unit with a small 1,800 mAh Li-ion battery, which GroWell says should be good for several years of regular use. Because it’s in three small pieces (a control pack that’s the size of an old Motorola Razr, a USB-C cord, and a flat pad that’s only as thick as a piece of cardboard), it’s easy to fold up and pack on a trip. That’s clutch, as you don’t want to miss treatments when traveling. (Note that if you stop using the device, your follicles will return to their previous state.)

Growing Pains?

It couldn’t be easier to use: Tuck the light pad inside the provided cap or one of your own, connect it via USB-C to the control module, and press the button. It will light up for the next 25 minutes while you go about your business. Because it goes in your own hat, the fit may not be perfect, and I did find myself adjusting it a bunch, which probably wouldn’t happen with some of the helmet-style devices.

In a 2013 study, the levels and duration provided by GroWell with every other day of use over 16 weeks helped everyone who participated in the study regrow some hair, on average 35 percent more for men and 37 percent for women. The same study showed that using more powerful lasers for longer may actually stunt growth a bit. I’m only estimating here, but I would guess I have at least 30 percent more hair than I would have without the treatment, and maybe more.