I notice an antidepressant effect if I use my light box in the early morning. However, I am phase-advanced, so I do not sleep well if I use the light in the morning. However, when I use the light in the evening, I do not notice an antidepressant effect. Would I get the effect by using the light in the mid-morning plus the evening?
You might find the following trick helpful: use the light in late evening, right before bedtime, for one week. (You may find your sleep episode delays.) Then, immediately switch to morning light at your new wake-up time. That will give you the desired phase advance, and your sleep may stabilize without premature awakening.