At-home LLLT gadgets have been on the market for the past 10 years, but this new model seems particularly promising. In its clinical trial, the results of which were published in Lasers in Surgery and Medicine, 47 women with a particular type of hair thinning known as androgenetic hair loss wore either a helmet with ordinary incandescent lights or the iGrow helmet every other day for 25 minutes during the 16-week trial. The group that wore the iGrow showed a 37% increase in hair growth compared to the women in the control group. MORE: 8 Ways To Disguise Thinning Hair Here’s what’s going on under the helmet: The particular wavelength of light sets off a chemical reaction that ramps up energy production within your cells, giving failing hair follicles the energy they need to thrive and multiply, explains study author Raymond J. Lanzafame, MD, FACS, a board-certified surgeon and expert in laser applications and laser research. The catch: The helmet costs $695 and only works for those with androgenetic hair loss, a condition in which follicles shrink, but don’t totally disappear, so they can be rehabilitated (in many other types of hair loss, follicles vanish entirely). It tends to show up as a widening part and thinning on the top or crown of the head; your doc will be able to tell you if your hair loss qualifies as androgenetic. If you do decide to use the iGrow, you’ll need to pair the product with other therapies and treatments, like topical minoxidil, to completely reverse your hair situation, says Nicole Rogers, MD, a hair transplant surgeon and board-certified dermatologist based in New Orleans. Think of it this way: If you’re overweight, exercising is effective, but you’ll also have to eat and sleep well to really reach your goal weight. MORE: 7 Food Fixes For Thinning Hair