A reader asks:

Q: Is there a rule of thumb for deciding whether to use the light box at a later time than recommended? I know you should try to have a consistent schedule, even on weekends, but sometimes that doesn’t happen. For example, if I am supposed to use the light box at 6:15 AM, but sleep two hours late on Saturday, should I still use the light box or skip that day? How about three hours? Thank you for your advice.


Our basic principle: once you’ve established a regular morning wake-up target with light therapy, it is better to use the lights later in the morning than to skip the day entirely. If you know that you are likely to oversleep, adjust your light box settings. On the other hand, if you plan to get up at an earlier time on a particular morning, skip the light therapy and return to it the next day.