Most standard antidepressants are no more effective than light therapy.
In fact they are probably just treating the symptoms and not the underlying cause. Experimentally, we are also studying melatonin, which given in tiny doses during the day, doesn't make you sleepy. If given in the afternoon, it shifts the body clock earlier, just like morning light. My guess is that many people will combine morning light therapy with the afternoon melatonin and will then not have to use so much morning light. Or maybe they won't have to use it immediately upon waking but be able to use it when they first get to work because they are getting a lot of the shift in the body clock from the melatonin.