Do The Seasons Have An Ability To Influence The Brain?

Do you seem to function more properly in summer than in winter? Well, you are not the only one. 

“I feel happy during summer and sad during winter”, may not be an arbitrary statement, after all. Besides the paramount impact that sunshine has in our lives, it is also a mood elevator which in turn can affect our cognition. Sunshine obviously varies with seasons. So does that dictate the overall functioning of our brains?


The latest research shows that answer is in the affirmative. By extension, as with the time of the year, the efficiency of the brain apparently can fluctuate even with the time of the day. Overall, this phenomenon, which quantifies the influence of season on our mood aspects, is termed as SAD – Seasonal Affective Disorder. Its chief symptoms are recurrent clinical depression. And they have been noted to be more prevalent in Northern latitudes, particularly the Scandinavian region, than in tropical climates, which is enjoyed by areas closer to the equator.

And according to one study, cognitive functioning – attention, memory and information processing have a strong correlation with depression. Incidentally, cognitive impairment of depression has not been tackled effectively with antidepressants.

Summer Smart

Same old-adults were seen to perform much better on neuropsychological tests during warmer months as if cognitive-age corresponded to a 4.8-year difference, noticeably in working memory and perception speed. Long term implications in cognition due to seasonal changes was understood when results showed that people were 24% more likely to be diagnosed with cognitive impairments including Alzheimer’s Disease if they were tested in winter or spring.

A paper in PNAS journal noted the brain functions of participants, over a year and a half, artificially deprived of seasonal stimuli. MRI readings exhibited a striking pattern of seasonal influence.

Sweet Serotonin

Though so far the understanding of this biological mechanism has only been partial, it’s being thought that serotonin, which governs the mood oscillates with the season. Additionally, expressions of upwards of various genes and even blood cell composition, are seen to fluctuate decisively with different seasons. Besides impacting the cognition, these variations impinge markedly on the immune system with winter registering a spike in cardiovascular, psychiatric and autoimmune diseases.

Same Ability, Different Output

It’s not that colder seasons reduce the ability to perform – it was seen to remain relatively stable throughout the year but the responses of the brains vis-a-vis the tasks varied. While metrics related to sustained attention peaked during the summer solstice and bottomed out with the advent of the winter solstice, working memory peaked around the autumn equinox and bottomed out around the spring equinox.

So it is not just John Denver then, that the sunshine on his shoulders makes him happy.

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