been a while since I watched, but from my fuzzy memory people getting less light in their eyes was linked/associated with nearsightedness, and since I work at a computer all day I figured I should try to maximize the light I get in them, so I started taking more walks and switched to auto mode (less light at night is important for sleep).

Another thing that pushed me to it was Eliezer Yudkowsky made a post about how his wife struggled with seasonal depression and a lightbox didn't help, but he tried increasing the light by setting up a ton of LEDs around their house and it actually worked for her.