New research explains why some people feel sad during winter


For many, the approach of winter is a time of seasonal depression, when gray clouds, sunless skies, and wet asphalt seem to conspire an atmosphere of haunting sadness that lingers until spring. To those who suffer from what scientists call seasonal affective disorder (SAD), these episodic periods of depression negatively affect almost every aspect of their daily lives. Fortunately, scientists are getting closer to pinpointing the exact source of SAD in the brains of people who suffer from this disorder.

Researchers at the University of Copenhagen are claiming to have identified the underlying reason why people experience SAD. Collecting data using positron emission tomography (PET) brain scans, researchers discovered that the brains of patients suffering from SAD developed higher than normal levels of a transporter protein called serotonin transporter (SERT). These protein compounds limit the activity of serotonin, which is responsible for feelings associated with happiness.

In an interview with the BBC, Brenda Mc Mahon, a lead researcher and neurobiologist at the University of Copenhagan, said, “The serotonin transporter (SERT) carries serotonin back into the nerve cells where it is not active – so the higher the SERT activity, the lower the activity of serotonin.”

Mc Mahon went to explain that “sunlight keeps [SERT production] naturally low, but when the nights grow longer during the autumn, the SERT levels increase, resulting in diminishing active serotonin levels.”

This study is the first of its kind to compare the brain scans of volunteers taken during winter to those taken during summer. “SERT fluctuations associated with SAD have been seen in previous studies, but this is the first study to follow patients through summer and winter comparisons,” said Prof Siegfried Kasper, of the European College of Neuropsychophar­macology.

Although the results are exciting, the study included only 34 volunteers, and will have to be expanded for more conclusive evidence.

Still, researchers hope studies like this will yield more effective therapies and treatments, which so far include a mix of light and cognitive behavioral therapies.

According to Sam Challis, information manager at mental health charity Mind, it’s possible to alleviate the effects of SAD by “eating a balanced diet, cutting down on caffeine and getting some exercise,” in addition to “spending as much time as possible outdoors because – even when it’s overcast – light will be higher than indoors.”

(Featured image by Matt Henley)


About Author

Kristian strives to enlighten and entertain readers. In addition to his teaching and editorial responsibilities, he is working on a science-fiction novel that promises not to include exoskeleton suits and anemic aliens floating in mysterious vats of green-tinted goop.

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