Why can i get really tired in the head when i focus on something on the computer? not when i watch a movie just when thinking hard. have depression.

I need clarification: What do you mean by, "tired in the head?" is this a headache, eye strain or a reaction to being in front of a computer screen 2long? Does it happen when ur reading disturbing material online? Headaches can bcaused by many things, physical and emotional. I encourage people 2rule out physical possibilities with their physician before assuming it is emotional. If it is not physical speak 2a therapist.