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IMAGE: Brain opioid receptors measured with positron emission tomography (A) and regions, where opioid receptor density varied seasonally. view more
Credit: University of Turku
Seasons have an impact on our emotions and social life. Negative emotions are more subdued in the summer, whereas seasonal affective disorder rates peak during the darker winter months. Opioids regulate both mood and sociability in the brain.
In the study conducted at the Turku PET Centre, Finland, researchers compared how the length of daylight hours affected the opioid receptors in humans and rats. In the study, we observed that the number of opioid receptors was dependent on the time of the year the brain was imaged. 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, says Postdoctoral Resear