Episode 84 of "Stargate-SG1"
s04e18 The Light

A member of another SG team, returning from an alien planet, commits suicide. The rest of his team begins to go into comas, and Daniel, who also visited the planet, attempts suicide. When SG-1 goes to the planet, they discover a hypnotic light show that not only induces memory blackouts, but alters their physiology so that they cannot leave the planet without becoming terminally depressed and ultimately dying of system shutdown. Trapped on the planet, they meet a young boy, Loran, who is apparently immune to the effects of the light system but who lost his parents. The team must figure a way to overcome the addiction or remain rapped on the planet forever.