The following contains spoilers for Secret Level Episode 7, "Crossfire: Good Conflict," which debuted Dec. 10 on Prime Video.

Dermatologists explain the science behind wildly popular treatments like red light therapy, which is now available at home—for a steep price. Full-face LED masks like this one can cost up to several ...

This transcript was created using speech recognition software. While it has been reviewed by human transcribers, it may contain errors. Please review the episode audio before quoting from this ...