A reader asks:

My rhythm is going to bed at about 5 AM and getting up at 1:30 PM. I recently tried a light box at 8:30 AM and kept it on four hours because I was reading. Since I did this 4 days ago I have been unable to sleep past 8:30 AM despite the fact that I still have been going to bed at 5 AM. Help… Is it possible I screwed up my rhythms somehow?

Answer:

Light therapy is a potent intervention that can be used to counteract the delayed sleep phase syndrome. But it must be done correctly, and certainly you have not followed appropriate procedures. The lucky thing is that “screwed up” rhythms can be corrected. Please review previous question about adjusting delayed sleep disorder symptoms for a discussion of productive strategies. In your case, it is likely that you produced an effect on your circadian rhythm exactly opposite to what you desired, sending it even later. Treatment needs to begin shortly before the end of your “physiological night,” which would have been around 12:30 PM — not 8 AM! — before you started using the lights. After you adjust to that time, you can begin edging the lights earlier toward your desired morning wake-up time. Since you have now used the lights at 8 AM, we cannot not know exactly where your rhythm lies, and where you should begin. So, your priority is to stop using the lights altogether in order to establish your current rhythm, and then start working from there. You may well need expert clinical supervision to succeed.