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Seasonal changes in daylight may affect consumers' brain function, study finds

Experts say that the findings could shed light on seasonal affective disorder

Photo (c) Fertnig - Getty Images
With Daylight Savings fast approaching and many consumers feeling stuck in the final push of the long winter months, researchers continue to explore the effects that these seasonal changes have on our well-being. 

A new study conducted by researchers from the University of Turku has found that seasonal changes in daylight may have an effect on consumers’ brain function. Using data pulled from tests on both mice and humans, the researchers found that varying exposure to daylight can affect the brain’s opioid receptors, which can impact motivation and pleasure, among other things. 

“On the basis of the results, the duration of daylight is a particularly critical factor in the seasonal variation of opioid receptors,” said researcher Lauri Nummenmaa. “These results help us to understand the brain mechanisms behind seasonal affective disorder.”  

How daylight affects our mental processes

The researchers had two test subjects involved in this study: mice and humans. The mice were kept in very controlled environments that allowed the team to manipulate how much light they were exposed to each day; one group of mice was exposed to constant daylight for the duration of the study while the second group experienced seasonal changes. The researchers also analyzed PET scans for more than 200 human participants and observed how their opioid receptors changed seasonally based on exposure to daylight. 

Ultimately, the researchers observed similarities in the brains of both the mice and the humans involved in the study. They found that the opioid receptors were significantly impacted during the fall and winter months to the point where it affected overall mood, appetite, and sleep quality.

The mice’s brain scans produced similar results. The researchers found that having less exposure to sunlight as the seasons changed caused the mice’s stress hormones to spike. They were also more susceptible to weight gain during this time. 

“In this study, we observed that the number of opioid receptors was dependent on the time of the year the brain was imaged,” said researcher Lihua Sun. “The changes were most prominent in the brain regions that control emotions and sociability. The changes in the opioid receptors caused by the variation in the amount of daylight could be an important factor in seasonal affective disorder.” 

Moving forward, the researchers believe that these findings can play an important role in how we understand seasonal affective disorder. Having fewer daylight hours during the winter months can significantly impact consumers’ mental health, and knowing the biological and psychological effects can help them be prepared for these seasonal changes. 

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