There's a common belief that the weather affects our mood, that we tend to become more depressed in the winter and that summer brings an emotional lift. This has been researched before in small studies that have found inconsistent results but a new study published in Psychiatry Research tested the idea on almost 14,500 people and found no link to weather, while the seasonal effects did not follow the common belief: depression was more common in summer and autumn.
The researchers, led by Dutch psychologist Marcus Huibers, tested both the effect of daily changes in weather and the influence of the season. They sent out thousands of invitations to people in Holland to complete a standard depression diagnosis questionnaire on the internet, in waves of a few thousand every week, over 18 months.
This allowed the researchers to check the exact day's weather against people's mood states.
Neither that day's temperature, the amount of sunshine or rainfall had any immediate effect on mood, and the seasonal changes were not what you'd expect from 'common knowledge': men had seasonal peaks of major depression and sad mood in the summer, while women had seasonal peaks in the autumn
Although there are some people who do seem to have depression triggered when winter arrives (a condition diagnosed as 'seasonal affective disorder' or SAD) this link doesn't seem to exist in the public as a whole.
I currently live in Medellín, a city without seasons, to the point where it is nicknamed as 'the city of eternal spring'. The locals says it used to be possible to tell the difference between the rainy seasons and dry seasons but over the last few years it's simply been impossible to make any distinctions.
Interestingly, this has an effect on how we assess people for dementia. One of the 'orientation' questions for the widely used 'Mini-mental state examination' or MMSE evaluation is 'what season is it?'.
As no-one knows what season it is, the assessment has to be scored out of 29 rather than 30, or it has to be replaced with something ad-hoc like 'what part of the day is it?'.
However, it would be also interesting to find out whether depression varies here by time of year to understand whether this effect is really to do with season, or perhaps to do with the significance of the date.
For example, self-harm and suicide has been found to vary more by significant public holidays than by time of year.
Does the weather make us sad? Meteorological determinants of mood and depression in the general population.
Psychiatry Res. 2010 May 20.
Huibers MJ, de Graaf LE, Peeters FP, Arntz A.
Department of Clinical Psychological Science, Maastricht University, The Netherlands.
It is a common and well-spread belief that people feel more depressed when the weather is bad. However, whether meteorological factors such as temperature, sunshine and rainfall can actually account for variations in the prevalence of depression in the general population has yet to be investigated. We aimed to assess the influence of weather conditions on the seasonal variation of depression observed in the general population.
We used data from a large-scale depression-screening programme in the south of the Netherlands. Seasonal prevalence of DSM-IV classified major depression and sad mood in a sample of 14,478 participants from the general population was calculated, and linked to mean daily temperature, duration of sunshine and duration of rainfall in logistic regression analyses.
The prevalence of major depression and sad mood showed seasonal variation, with peaks in the summer and fall. Weather conditions were not associated with mood, and did not explain the seasonal variation we found.
We conclude that, contrary to popular belief, weather conditions and sad mood or depression do not seem to be associated. Future studies might use daily measures of well-being as outcome. Copyright © 2009 Elsevier Ireland Ltd. All rights reserved. PMID: 20494449