"The best way to use an LED light therapy mask is on clean skin," says Dr. Engelman. After washing your face in the morning or at night, set your mask to the proper wavelength, then put on goggles.

LED-based ‘light therapy’ has been big news in beauty for a while now, but how much impact can it really have on the skin? Here, three women put it to the test. Cast your mind back to your ...