Light and weather seem to have a big influence on our mood. Already in the Greek era, Hippocrates referred to the importance of seasonal changes in the genesis of certain diseases, as well as bodily changes caused by cold or heat.
There are seasons of the year when some mental illnesses worsen or produce mild symptoms such as low mood, increased tiredness, difficulty sleeping and poor concentration. If these symptoms are very marked, it may be that a seasonal affective disorder sensitive to autumn and winter is developing in the individual, disappearing when good weather appears and the days are longer.
What does seasonal affective disorder consist of?
Seasonal affective disorder or SAD occurs in about six out of every hundred people, being more common in adults, but it can also occur in children and adolescents. The number of women affected by this disease is greater than that of men, although biology, family history, environment and individual experiences make some people more predisposed than others to develop it.
SAD is a form of depression that coincides, according to the most recent studies and research, with the lack of light exposure during the autumn and winter months and hormonal and neurotransmitter alterations.
It is characterised by the presence of mood changes typical of depression, such as fatigue, feelings of hopelessness, irritability, sadness, anxiety, anhedonia, decreased libido, etc. also showing a predominance of vegetative symptoms such as hypersomnia, increased appetite and weight, physical fatigue and high sensitivity to interpersonal rejection.
Why does that happen?
Melatonin is a hormone that we naturally secrete, whose main function is the regulation of sleep-wake cycles. The secretion of melatonin starts to increase in the afternoon, staying at high levels almost throughout the night and decreasing when the sun rises. With serotonin, the opposite occurs, increasing when the person is exposed to sunlight, so its levels are very low in winter, being associated with symptoms such as sadness and irritability. Therefore, if the light decreases, as it usually does in autumn and winter, hormonal imbalances that affect our mood can occur.
Thus, when the days are shorter in autumn and winter and the hours of darkness are longer, an increase in melatonin levels and a decrease in serotonin can be produced, sometimes creating biological conditions for bad mood, to which we must add the history the individual's family, the context in which he/she is located and their personal conditions and experience.