Many people complain of a certain decrease in mood during the winter months. Sometimes this "metereopathy" becomes pathological and in this case we speak of SAD ( Seasonal affective disorder ) or seasonal mood disorders. Women suffer the most and, not surprisingly, SAD is also more common among people living far from the equator, where there is less light in winter. And it is precisely the scarcity of light that is called into question as a trigger for certain biological adjustments, which according to scholars would explain the reduction in mood during the winter months.
In this regard, we have seen how in winter the levels of SERT, the serotonin transport protein, increase. SERT binds to serotonin in the synapse, returning it to the presynaptic neuron and preventing it from interacting with its receptors. Since serotonin is also known as a good mood hormone, the higher the SERT levels, the greater the tendency to depression; not surprisingly, different antidepressant drugs act precisely on the SERT protein to increase serotonin levels and with them the good mood.
Another biochemical explanation of SAD concerns the increased secretion of melatonin in response to low light; this phenomenon could explain the greater drowsiness and the less activity that many people complain about in the winter months.
