The fact that the weather outside affects people’s mood has been conventional wisdom for ages now. What is less known by some, however, is how and why that really happens. For example, there are plenty of popular beliefs about rainy weather increasing the chance of people feeling down in the dumps or unmotivated.

In 2008, Jaap Denissen conducted a study about the effects of weather on people’s moods, and discovered that actually the correlation between weather and mood is much less significant and that the main factor influencing the mood is sunlight. The less in contact with sunlight a person is, the more they present depression-like symptoms.

So it’s not really the rain that drags people down, but rather the lack of exposure to sunlight, according to this study. The explanation for this is related to the creation of vitamin D, which has been found to change serotonin levels in the brain. Serotonin is a key hormone in mood regulation – lower levels of serotonin are linked to symptoms of depression, while higher levels correspond to happier, more hyper moods. This seems to explain quite nicely why during the winter, when days are shorter, people might feel less productive and more inclined to stay inside and rest.

While most people are accustomed to the climate of the region they live in and the changing seasons feel like a natural, organic part of their lives, the beginning of a new season can trigger pretty intense reactions for some individuals.

Seasonal Affective Disorder (SAD)

Sally Rohan (PhD) is a Seasonal Affective Disorder (SAD) expert. She explains that “at the extreme along the continuum of seasonality is full-blown winter seasonal affective disorder (SAD), a syndrome involving recurrent depressive episodes during the fall and winter months with periods of remission in the spring and summer.” There are still plenty of aspects of SAD that require further research, but that doesn’t diminish in any way the easily visible effects that seasonal transition has on people.

So is there any treatment for SAD? Let’s see what Sally Rohan’s response to this question was in a press release for A.P.A.:

“The most widely used and extensively investigated treatment for SAD is light therapy (i.e., daily exposure to bright artificial light during the symptomatic months).”

She goes on by explaining that another method for treating SAD could consist of “a novel cognitive-behavioral therapy”, which is showing some promising results so far:

“CBT is a type of talk therapy used and researched extensively for non-seasonal depression since the 1960s, but we are the first group to apply the treatment to SAD. We previously published a clinical trial for SAD that compared standard light therapy, CBT and the combination of CBT and light therapy to a control group on a wait list for treatment. We found that CBT, light therapy and combination treatment all improved depression more than the control group and all three of these methods showed large and comparable improvements in SAD symptoms across the six weeks of treatment in the winter.”

You can read the full press release here: Seasonal Affective Disorder Sufferers Have More Than Just Winter Blues

Other research papers, however, claim that the correlation between weather and mood is much higher than the findings shown in Denissen’s study.

Sanders and Brizzolara (1982) tested 30 college students and found out that high humidity could predict symptoms such as lack of vigor, elation and affection. Two years later, Howard and Hoffman (1984) tested 24 subjects by asking them to keep track of their mood (with the help of a mood questionnaire) for a period of 11 days, and they too found a significant correlation between the weather and the subjects’ mood, especially with regards to humidity.

So maybe these studies only used small samples and can be dismissed based on that, but in 1974 Faust et al. used a sample of 16.000 students from Switzerland and found that 1/3 of girls and 1/5 of boys responded negatively to some weather conditions. The subjects reported poor sleep, irritability and dysphoric moods.

But this isn’t the only thing all these studies say. There are plenty of mentions about the negative effects of weather on people’s moods, and – if you consider what Denissen’s study shows (among many others), weather also influences the mood in positive ways. Let’s not discount that.

And more than that, let’s not discount each person’s life experience, personality and physical characteristics. What is also true is that each person has a set of preferences in regard to the weather outside. So it would be unfair to say that no person feels depressed or cranky when it’s sunny. Maybe some people really do loathe the bright sunlight.

Fun facts

Minnesotan diners tipped more generously on sunny days, according to this study .

. Better daily stock returns in sunny weather were noticed by American studies .

. In a 2013 study by Nicolas Guéguen, an attractive man approached unaccompanied young women and asked for their phone numbers. “I just want to say that I think you’re really pretty”, he’d say. “I’ll phone you later and we can have a drink together someplace”. “Antoine” obtained a success rate of 22% on sunny days, but only 14% when it was cloudy. Rather impressive!

by Nicolas Guéguen, an attractive man approached unaccompanied young women and asked for their phone numbers. “I just want to say that I think you’re really pretty”, he’d say. “I’ll phone you later and we can have a drink together someplace”. “Antoine” obtained a success rate of 22% on sunny days, but only 14% when it was cloudy. Rather impressive! The same study about Minnesotan diners found that helping rates fluctuated as temperatures dropped or rose.

Joseph Forgas published a study which shows that sunshine can also affect mental sharpness. Shoppers exiting a store were quizzed about ten unusual objects – including a toy tractor and a pink piggy-bank – that had been placed in the check-out area. They correctly recalled seven times more objects on cloudy days than on sunny ones.

which shows that sunshine can also affect mental sharpness. Shoppers exiting a store were quizzed about ten unusual objects – including a toy tractor and a pink piggy-bank – that had been placed in the check-out area. They correctly recalled seven times more objects on cloudy days than on sunny ones. A recent study of news media coverage of the 2008 Beijing Olympics found that stories filed by American journalists contained more negative words on hotter days, even when they were writing about China in general rather than the Games in particular.

of news media coverage of the 2008 Beijing Olympics found that stories filed by American journalists contained more negative words on hotter days, even when they were writing about China in general rather than the Games in particular. by US psychology researcher Matthew Keller and colleagues showed that beneficial effects of warm and sunny conditions on mood were only seen in people who had spent more than 30 minutes outdoors that day. Good weather even had negative effects on mood for people confined indoors, who perhaps gazed enviously outside at the solar fun they were missing.

Did you notice any interesting changes in your mood in relation to the weather outside? What do you think about these studies? Share your thoughts.

—

Denissen, J.J.A.; Butalid, Ligaya; Penke, Lars; van Aken, Marcel A. G. (2008). The effects of weather on daily mood: A multilevel approach. Emotion, 8(5), 662-667.

Faust, V., Weidmann, M. & Wehner, W. (1974). The influence of meteorological factors on children and youths: A 10% random selection of 16,000 pupils and apprentices of Basle City (Switzerland). Acta Paedopsychiatrica: International Journal of Child & Adolescent Psychiatry, 40(4), 150-156.

Howarth, E. & Hoffman, M.S. (1984). A multidimensional approach to the relationship between mood and weather. British Journal of Psychology, 75(1), 15-23.

Sanders, J.L. & Brizzolara, M.S. (1982). Relationships between weather and mood. Journal of General Psychology, 107(1), 155-156.