Not all at-home red-light devices have been thoroughly, independently tested, researchers say. Credit: Guy Corbishley/Alamy In 2021, dermatologist David Ozog was on holiday with his family in the Bahamas, when his 18-year-old son had a massive stroke. The teenager was airlifted to Florida, and then to Chicago for surgery. As his son was lying partially paralysed in a hospital bed, Ozog got a call from a colleague who had an unconventional suggestion. Forget SkinTok: the real science of skincare and why it matters for your healt The colleague, a dermatologist at Harvard Medical School in Boston, Massachusetts, told Ozog about research he was conducting with the US Department of Defense. Early results hinted that red and near-infrared light applied to the head might protect neural tissue after brain injury. He urged Ozog to consider trying it on his son. Ozog stayed up until 4 a.m.…