Tim Newman, writing for Medical News Today, has reported on a study that found no significant difference in depressed moods among participants between cold and warm seasons. This is in contrast to an earlier acceptance among psychologists of Seasonal Affective Disorder, a long-term change of mood due to seasons.
This study, published in Clinical Psychological Science, pooled an earlier study's data of depressive symptoms for more than 34,000 people across the U.S. The people participating recorded their symptoms every day for two weeks leading to their phone interviews. Statistical analysis of their reported moods showed that they did not vary by season.
As Tim Newman observes, "Depression is, by its very nature, episodic. Symptoms wax and wane. This means that a depressed patient is likely to suffer episodes during some winters but also during some summers." And, according to the study's authors, "being depressed during winter is not evidence that one is depressed because of winter."