A reader asks:

I suffer from panic disorder. I used a light box for four days for 30 minutes starting at 6:30 a.m. On the fourth day I experienced a severe panic attack which lasted from about 8:00 P.M. thru 5:00 A.M. I did not continue using the light. The following day I slept through the night. The last two nights I have had the same intense anxiety. I can’t sleep at all at night. Could I have messed up my internal clock and will it ever go back to normal? I need to get up for work at 6:00 a.m., but I can’t even fall asleep until then. I don’t know what I should do. Any advice would be greatly appreciated.


Very sorry to hear this, but you have provided an important lesson for others. Light therapy is not advised for people with panic disorder–indeed, everyone with a “DSM-V Axis I” diagnosis should use lights only under doctor’s supervision. You should contact your doctor immediately for medications that will relieve your current symptoms. Don’t worry about your internal clock, it will readjust quickly on its own. Your being awake all night is most likely a side effect of light-induced anxiety and hyper-activation that will subside. If you were trying to treat depression with the light, that might still be possible with a far lower dose of light, but now you have seen the risk involved.