I have very high prior against light therapy on forehead or scalp reducing inflammation in brain. There is thick bone between skin and brain! Blood supply to skin on head is separate system to blood supply to brain. Maybe beneficial effect on skin, creates healing particles in blood, blood carry them to brain. But have to go long way round. Also cross blood-brain barrier.
Phototherapy for SAD is different, more plausible, because proposed mechanism is direct via photonic stimulation of retina to influence biorhythm-generating processes. Signal passes in to brain by nerves, not blood.
But rigorous self-experimentation is good idea with low-risk treatment. So I wish you good luck even though I count low chance of success, except for placebo effect.
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