The Effects Warm Weather Has on Mental Health & Vitamin D

As the weather continues to warm up as we head into the summer, we’re encouraged to get outside and move around more.

The warm weather has a profound impact on our overall health and wellbeing — especially in regards to our mental health. Getting outside exposes the skin to UV light, which is necessary for driving vitamin D production. Additionally, warmer weather is correlated with improvements in cognitive function, mood, and motivation to exercise and move around more.

In this article, we’ll cover 3 ways warm weather positively affects our mental health and wellbeing.

Warm Weather Increases Vitamin D Production

Vitamin D is essential for our health and wellbeing. When vitamin D levels are low we become less adaptive to sources of stress, our hormones can become dysregulated, and our energy levels take a sharp nosedive.

This essential vitamin acts more like a hormone than a vitamin — working to regulate our calcium levels and hormone production.

As you’re probably familiar, vitamin D is produced in the skin with the help of UV light from the sun.

In the winter, when the sun is at its lowest point in the sky and we spend our days indoors or covered by clothing, vitamin D levels tend to decline. This is especially true in those of us with darker complexions.

When spring finally arrives, and we return to the parks and beaches, or spend more time outside, unsurprisingly, vitamin D levels go up. Along with this comes a variety of improvements in our health as well — most notably on our mood and immune function.

The Projected Effects of Global Warming on Vitamin D

Since we already know that more sun exposure = increased vitamin D production — it begs the question; will global warming improve our global issues with vitamin D production?

A 6-year study out of Germany explored this question in more detail [1].

The study found that the two years with the highest recorded average temperatures (2018 and 2019) were correlated with the lowest incidences of vitamin D deficiency.

The idea is that when temperatures are hotter, people wear less clothing (aka, expose more skin to the sunlight), and generally spend more time in the sunshine.

The colder years had people spending more time indoors or covered up with jackets, sweaters, and long pants.

While global warming is certainly something we should not be looking forward to, it may at least bring some improvement to the chronic problems we face with vitamin D deficiencies — especially in more Northern regions of the world.

Warm Weather Improves Memory & Cognitive Function

An interesting study published in the American Journal of Physiology explored the effects of body temperature on memory. Fourteen subjects were given tasks investigating their physical and mental performance in a variety of categories — including working memory, subjective alertness, visual attention, and reaction times. Participants performed these tests in a variety of different ambient temperatures.

The results found there was an optimal thermal zone for the body temperature of participants was 0.15°C above normal body temperature (37.3°C) — which is aligned with the increased ambient temperatures in the spring and summer.

However, any improvements were lost when body temperature reached 38.5ºC or higher — which was simulated by exposing participants to a 43°C, humid climate.

It appears our mental memory capacity, reaction times, and subjective alertness is optimized in warm, but not excessively hot summer weather.

Warm Weather Correlates With Higher Activity Levels

A Canadian study followed close to 1300 adolescents between the ages of 12 and 13 for 5 years to track their activity levels. The data was then correlated with information obtained by Environment Canada to explore the impact the weather had on activity levels.

The study found that activity levels were 4% lower, on average, for every 10 mm of rainfall, and 2% higher for every 10-degree increase in temperature.

The findings of this study confirm what many people already know to be true. When the weather is nice, we’re more likely to feel motivated to get outdoors and exercise or move around. This includes going for walks, hikes, basketball, biking, or other activities.

Increasing daily exercise has a big impact on our mental health and wellbeing. Studies have shown that increased activity levels are correlated with improvements in sleep, increased libido, better endurance, stress reduction, improvements in mood, and much more.

Final Thoughts: When is Warm Weather Detrimental to Mental Health?

We’ve highlighted the three main positive effects warm weather has on our mental health — but can the heat become detrimental?

The short answer is yes, and there appears to be a sweet spot in the temperature for maintaining the optimal mental health of humans. This sweet spot appears to be within the range of 20 and 35ºC.

For example, the same study that found improvements in cognitive function in warmer weather noted a reduced memory capacity and reaction time when body temperature was raised above 38ºC — which was simulated by ambient temperatures of 43ºC.

Another study found that for every one standard deviation of temperature, there was a 4% increase in interpersonal violence and a 14% increase in group violence. This has some scientists worried about the impact global warming may have on conflict around the world.

As the weather continues to heat up, we can expect an improvement in our mental health and wellbeing as a whole — largely driven by the increased production of vitamin D (but there are other factors too). But be careful when the temperature is exceptionally high (over 35ºC). Take precautions to keep cool, limit the amount of time you spend in the sun, and drink plenty of water.

References Cited

  1. Kraus, F. B., Medenwald, D., & Ludwig-Kraus, B. (2020). Do extreme summers increase blood vitamin D (25-hydroxyvitamin D) levels?. PloS one, 15(11), e0242230.
  2. Wright Jr, K. P., Hull, J. T., & Czeisler, C. A. (2002). Relationship between alertness, performance, and body temperature in humans. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology.
  3. Bélanger, M., Gray-Donald, K., O’loughlin, J., Paradis, G., & Hanley, J. (2009). Influence of weather conditions and season on physical activity in adolescents. Annals of epidemiology, 19(3), 180-186.
  4. Sharma, A., Madaan, V., & Petty, F. D. (2006). Exercise for mental health. Prim Care Companion J Clin Psychiatry, 8(2), 106.