The changing of the seasons has a significant impact not only on nature and animals, but also on the human body. Admittedly, it’s no longer as significant as it was thousands of years ago, because over time we’ve adapted our environment to make life as comfortable as possible. We live in heated homes, drive cars, import food year-round from the other side of the globe, and take exotic vacations during the coldest months. However, there are natural conditions whose effects we have, fortunately, not yet fully mastered. For example, the lack of sunlight—which is most noticeable around the winter solstice—cold weather, or nature in a state of quiet repose, even if it’s a bit lacking in colorful stimuli.
Despite all efforts to alleviate the discomfort that winter brings, we are influenced by evolutionary mechanisms. These include not only increased fatigue and the need for rest, but also changes in the brain. What causes this? For thousands of years, the body has cleverly adapted to a lack of light (and the associated vitamin D deficiency) and, above all, to a lack of high-quality, balanced food. And because the brain consumes roughly 20% of the body’s energy, it simply had to scale back its function to increase the chances of survival for the entire organism. However, as we know, it’s difficult to override evolution with modern habits, which is why the brain still changes during the colder months—even today, when we have plenty of food year-round and are certainly not at risk of dying from starvation.
And which brain functions are affected by these seasonal changes in brain activity? So far, only a few research teams have investigated this question. The most interesting findings came from these two studies:
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- Researchers from the University of Liège in Belgium monitored a group of 28 people for 18 months and found that their attention fluctuated the most. While it peaked in June, it reached its lowest point in December. Working memory peaked in September but gradually declined over the winter, reaching its lowest point in March.
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- Another team of researchers from the University of Toronto studied over 3,000 older adults from Canada, the U.S., and France, focusing on symptoms of Alzheimer’s disease in these participants, only some of whom actually had the disease. In addition to cognitive functions, the symptoms examined included physical activity, sleep quality, and symptoms of depression. They found that typical symptoms of dementia were most pronounced in winter and spring. In contrast, symptoms decreased significantly in summer and fall.
The influence of the seasons on brain activity is therefore demonstrable. However, awareness of these mechanisms has not yet reached the general public. Yet it would be more than welcome if, during the colder months, demands—such as the pace of work or the school curriculum—were scaled back. If people had more time to rest and didn’t let themselves get stressed out by the pre-Christmas frenzy. Perhaps this would then reduce the incidence of so-called seasonal affective disorder, which is characterized by feelings of sadness and depression and occurs specifically during the winter months.
Sources:
https://www.pnas.org/content/113/11/3066.abstract
https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1002647#pmed.1002647.ref002
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