Seasonal Affective Disorder is probably a myth, say psychologists
There is no evidence that Seasonal Affective Disorder, or SAD, is real and just because people are depressed in winter, it doesn't mean lack of sunlight is to blame
Published 22/01/2016 | 09:55
Seasonal Affective Disorder, the condition where people become depressed because of the lack of sunlight in the winter time, is probably myth, scientists have concluded.
A large scale study of adults in the US found that levels of depressive symptoms do not change from season to season or in different levels of light.
The researchers concluded that the findings are ‘inconsistent with the notion of seasonal depression as a commonly occurring disorder.’
“In conversations with colleagues, the belief in the association of seasonal changes with depression is more-or-less taken as a given and the same belief is widespread in our culture,” said Dr Steven LoBello, a professor of psychology at Auburn University at Montgomery.
“We analysed the data from many angles and found that the prevalence of depression is very stable across different latitudes, seasons of the year, and sunlight exposures.”
Seasonal Affective Disorder (SAD) has been a recognised condition since the late 1990s. To receive a diagnosis patients must exhibit major depressive symptoms which coincide with specific seasons. In most cases, patients report an increase of symptoms in the autumn and winter and a decrease in symptoms in spring and summer.
The NHS currently recommends that people see their GP if they experience low mood and and are struggling to cope. Doctors often recommend light boxes and even cognitive behavioural therapy as a treatment.
But recent studies have challenged the validity of earlier SAD research, including the fact that SAD is typically identified by asking patients to recall past depressive episodes over the course of the previous year or more.
To test whether depressive symptoms got worse in the winter, the researchers examined data from a total of 34,294 participants ranging in age from 18 to 99 who took part in a phone survey about their health throughout 2006.
Participants were asked how many days in the previous two weeks they had experienced symptoms of depression. They then checked geographical location and sunlight exposure for each respondents.
The results showed no evidence that symptoms of depression were associated with any of the season-related measures. People who responded to the survey in the winter months, or at times of lower sunlight exposure, did not have noticeably higher levels of depressive symptoms than those who responded to the survey at other times.
And the researchers did not find any evidence for seasonal differences in symptoms when they specifically looked at the subsample of 1,754 participants who scored within the range for clinical depression.
“The findings cast doubt on major depression with seasonal variation as a legitimate psychiatric disorder,” the researchers conclude.
They argue that: “being depressed during winter is not evidence that one is depressed because of winter.”
The researchers said it was clear that if SAD did exist it could only be affecting a very small proportion of the population.
“Mental health professionals who treat people with depression should be concerned about their own and their patients’ accurate conceptions about the possible causes of depression,” added Dr LoBello
“Pursuit of treatments based on false causes is unlikely to lead to rapid and durable recoveries.”
The research was published in the journal Clinical Psychological Science.