We may all know that sun makes us feel happier, and most of us have probably heard of Seasonal Affective Disorder (SAD), which causes depression in sufferers during the year’s cold and rainy months.
However, a new study reveals that it’s not just the blazing sunshine of summer and the downpours of winter that affect our mood – it’s the daylight itself.
A team from Brigham Young University (BYU), Utah, analysed six years’ worth of archived environmental and mental health data (from 16,452 adults undergoing mental health treatment) and discovered that our mental and emotional health relies on the amount of time between sunrise and sunset – not whether it’s actually warm and dry.
Which means that it’s not the horrible weather or pollution making a difference to the way we feel, but the amount of daylight hours we’re exposed to.
Mark Beecher, clinical professor and licensed psychologist in BYU Counseling and Psychological Services, told the BYU website that it was a “surprising” outcome: “On a rainy day, or a more polluted day, people assume that they'd have more distress. But we didn't see that.
“We looked at solar irradiance, or the amount of sunlight that actually hits the ground. We tried to take into account cloudy days, rainy days, pollution […] but they washed out. The one thing that was really significant was the amount of time between sunrise and sunset.”
So even if it’s raining and blowing a gale outside, getting out in the light should keep your levels of “emotional distress” stable.
While previous research has delved into the weather’s effect on mood, the authors of this study say it’s more in-depth, having analysed 19 meteorological variables such as wind chill, rainfall, solar irradiance, wind speed and temperature, used data that provided weather updates down to the minute in the exact area the patients lived, and had access to records detailing several aspects of psychological distress (which they could then cross-match with the environmental information).
Read more: 10 proven ways to get on top of SAD
As the BYU website points out, the source of the data means this applies to the clinical population at large, not just those officially diagnosed with SAD.
The study, published in the Journal of Affective Disorders, came about after Lawrence Rees, a physics professor at BYU, had a casual chat with clinical professor Beecher about whether the recent weather had seen a spike in Beecher’s patients.
In his job, Rees had access to weather information, while Beecher had access to emotional health reports for the same area, so they combined their assets.
The paper’s conclusion reads: “Seasonal changes in sun time were found to best account for relationships between weather variables and variability in mental health distress. Increased mental health distress was found during periods of reduced sun time hours.”
All of which says to us: buy yourself a brolly and get the hell outside.