A study of nearly 35,000 adults shows no data that depression symptoms get worse in the winter. The study is published in Clinical Psychological Science. This diagnosis was added in 1987 to the “Diagnostic and Statistical Manual of Mental Disorders” which is a listing of mental health diagnoses used by psychiatrists, physicians, psychologists and others. It looks like it should be taken out.
The research studied 34,294 participants, age range 18 – 99 years. Using geographic location information for the participants, the day of the year, the latitude, and the amount of sunlight exposure were all catalogued. There was no evidence that symptoms of depression were related to any of the season-related measures. That is, people who responded to the survey in the winter months, or at times of lower sunlight exposure, did not have higher levels of depression. There is no indication that depression is related to sunlight exposure. So don’t get a sunlight lamp (SAD lamp) if you are depressed in the winter. The article calls the idea of “winter depression” a “folk theory”. I might call it an “old wives tale”.
The full text of the published article is available for free right here.
A summary is found right here.
We could compare to the 17th to 19th century diagnosis of “Nostalgia”. This was called Swiss illness, Schweizerheimweh (Swiss homesickness) in German, mal du Suisse (Swiss illness) in French, because it was thought to be common among Swiss mercenary soldiers.
Link to a helpful article about Nostalgia as a medical diagnosis is found right here.