Magnetoreception attributed to the efficacy of light therapy.

A group of specialized photoreceptors are suggested to amplify the weak interaction of the geomagnetic field with a single electron spin to the level of photon detection, resulting in a modulation of the response to light. Under exposure to rotating magnetic field, the size of pinealocytes is bigger at night than during the day in spring, but there is no day-night difference in autumn. Specialized photoreceptors are hypothesized to modulate the response of the photoreceptive system to light, and the pineal response to a magnetic stimulus, in patients with winter seasonal affective disorder (SAD). This could explain why some winter SAD patients show excessive sensitivity to light in winter.