Seasonal depression does not exist
Beginning his work, psychologist Stephen Lobello from the University of Auburn (Alabama) and his colleagues did not set themselves the task of refuting the existence of this disorder. They wanted only to more accurately determine the time interval when the ATS is exacerbated, and find out how much its manifestations vary from season to season. In addition, they were interested in whether the prevalence of ATS depends on a particular latitude. "We assumed that in the northern latitudes, because of a short light day in winter, this depression is more common," says Lobello.
Researchers have not been able to detect correlations between the depressive state and the duration of daylight hours
To this end, data from a single large-scale population survey conducted in 2006 by the US Centers for Disease Control and Prevention were analyzed, in which respondents answered questions commonly used to diagnose depression. Researchers were primarily interested in the date of the survey and the location of the respondent. In each case, they determined the duration of a day's light at this place on the day of interview.
As data were processed, it became clear that no correlation was found between the depressed state, the time of year and the duration of daylight. The researchers at first did not believe in themselves and assumed that they accidentally missed this relationship - they had to process too much data. Therefore, they further analyzed the responses of those respondents who had been diagnosed with depression. Nevertheless, no data that would indicate a seasonal disorder was still found.
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Maybe the answers were unreliable because the survey was conducted by phone? This version also disappeared, because other patterns characteristic of those suffering from depression in the survey were fully apparent (for example, the fact that women and unemployed are more likely to suffer depression).
How to explain the results of this study? Perhaps it's about the questions. Researchers have previously wondered with what time of year the depression is more often associated and at what latitudes it is more prevalent. But in earlier surveys the questions were related to the SAR and, perhaps, involuntarily pushed the respondents to the given answer.And in the survey conducted by the Centers for Disease Control and Prevention, only 8 standard questions were included to identify a major depressive disorder, while no special questions related to ATS were asked.
Lobello and his co-authors do not make any categorical conclusions from the results (it is clear that these data need further verification). However, it can not be ruled out that the extent of the seasonal affective disorder is greatly exaggerated and that in fact they are affected by the units, while other patients are not correctly diagnosed, Lobello suggests.
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