As the mercury rises, make sure you don't get summer SAD

Staying out of the sun completely can leave us deficient in vitamin D and prone to depressive symptoms

A woman shields herself from Abu Dhabi's summer sun. Ryan Carter / The National  

As Earth tilts her face towards the Sun, temperatures rise. Last week the hottest place on the planet was Mitribah, a province in northern Kuwait, where it reached 51.4C. Some parts of the UAE were not too far behind, either. This rise in temperature brings obvious health risks, such as heat exhaustion, sunburn and heatstroke. It can also have surprising impacts on our psychological wellbeing.

If, like me, you grew up in a relatively cold, wet climate – the north-west of England, in my case – the idea of summertime sadness sounds crazy. My childhood drawings typically included an anthropomorphised Mr Sun, who always sported a beaming grin.  Summer was smiles, warmth, long days, ice cream, and trips to the seaside. How could such a season ever be associated with anything other than positivity and emotional wellbeing?

It turns out that some people experience recurring depressive episodes that routinely arise during the summer months. The American Psychiatric Association officially recognised this condition as seasonal affective disorder (SAD) in 1987. In Europe and North America, the most common pattern for SAD is for depression to appear in autumn or winter. There are, however, a small minority of patients whose depressive episodes regularly arrive in the spring or summer. When the disorder follows a summertime pattern, it is typically termed summer SAD.

Summer and winter SAD differ in terms of their typical symptom profiles. Summer SAD is associated with insomnia, agitation, reduced appetite and weight loss, while winter SAD is characterised by hypersomnia (sleeping too much), lethargy, fatigue and weight gain – kind of like a wintertime hibernation.

Summer SAD has received far less research attention than its wintertime counterpart, and we know far less about what might cause it. One idea, however, is related to body clock disturbance, or to use the technical term, circadian rhythm disruption. It is suspected that the extended hours of daylight and the shorter nights, characteristic of summertime in the northern hemisphere, play havoc with some peoples’ sleeping patterns, leading to insomnia and summertime depressive episodes. Another current idea is that summer SAD is connected to allergies, with some allergens, such as pollen, being more common in the spring and summer.

None of these ideas, though, would explain summer SAD in the UAE. For one, the nation is relatively close to the equator, so daylight length doesn’t vary much between winter and summer – in technical terms, the photoperiod is relatively stable. Similarly, concerning the allergies idea, in the UAE it is the cooler months when the pollen count tends to be higher.

Another possible explanation for summer SAD that does work for the UAE is that the condition is related to low levels of vitamin D, brought on by sun avoidance. If we are heat-averse or don’t like too much sunlight on our skin, then we might avoid the sunshine as much as possible in the hot summer months. Our own research at Zayed University, carried out over a number of years, confirms a link between vitamin D deficiency and depression. There also appears to be a pattern that worsens in the summer and improves in the winter.

For one of our studies titled, "Sunshine, Sadness and Seasonality" and published in the International Journal of Mental Health Promotion in 2011, we followed 197 Emirati college students over a year, assessing vitamin D levels and depressive symptoms in the winter and the summer. Vitamin D deficiency and depressive symptoms were linked, and both were significantly worse in the summer.

Sun on the skin is the greatest source of vitamin D, but when the mercury is rising, we might automatically opt for the cool and calm of the great indoors. In the absence of adequate supplementation, following this path makes us likely to end up deficient in vitamin D. When we feel depressed, we tend to become withdrawn and inactive and, therefore, even less likely to get outside for the limited spells where it is possible at the height of summer. In these circumstances, it is easy to see how vitamin D deficiency and depression could make each other worse.

In another of our studies, published in 2017 in the Community Mental Health Journal, we worked with a group of Emirati college students who had severe depressive symptoms and severe vitamin D deficiency. We developed a 12-week behavioural intervention, which involved making minor lifestyle changes ensuring they got regular and safe sun exposure. By week 12 of the study, all of the participants had significantly improved, showing both increases in vitamin D levels and decreases in depressive symptoms.

The challenge of preventing summer SAD in the UAE might lie in finding a healthy balance between getting safe sun and avoiding the health risks associated with high temperatures and UV exposure. It’s a difficult balancing act, but definitely manageable. After all, people have lived in this region for thousands of years before the invention of air conditioning.

Justin Thomas is a professor of psychology at Zayed University