This article was written by Michael Mak and was published in the Toronto Star on June 20, 2024.
MICHAEL MAK IS A STAFF PSYCHIATRIST AND SLEEP MEDICINE SPECIALIST AT THE CENTRE FOR ADDICTION AND MENTAL HEALTH.
It is the middle of June and the sight of dirty snowbanks, wet slushy pant legs and the almost permanent overcast skies of January are long gone. Thank goodness. During that time, some of us might have been coping with Seasonal Affective Disorder, a form of debilitating depression that affects three to five per cent of Canadians, occurring mostly in the winter months. Of course, a greater proportion of people suffer from less severe forms of this depression — with up to one-third of Canadians describing with some form of “seasonal blues” that causes milder symptoms of loss of enjoyment and low energy.
We think these seasonal forms of depression are associated with the lower levels of (sun)-light exposure during winter and routinely prescribe bright light exposure — bright light “SAD” lamps are an effective treatment — and exercise to patients and ask them to look forward to the sunnier, happier days of spring and summer, when we can expect their mood to stabilize and improve.
But now that the warm weather and sunshine have finally arrived, I am hearing from some people that the summer weather is actually aggravating to them. That the extreme heat is in fact causing higher levels of irritability and negative mood swings.
Turns out complaints that being too hot makes people grouchy are not just anecdotal.
Believe it or not, there is scientific evidence that extremes in hot temperature are associated with an increase of mental health challenges. A peer-reviewed publication from 2023 by researchers from Imperial College London’s Institute of Global Health Innovation demonstrated that a one degree Celsius increase in average monthly temperature was associated with a 1.5 per cent increase of suicide incidence. The same study showed that during heatwaves (defined as daily temperatures of at least 35 C for three days), hospital admissions for mental health issues increased by 9.7 per cent. The authors clarify that these signals should be interpreted in the context of “higher temperatures, relative to the norm for that location and time of year.” Even though their results were consistent with previous reviews, the authors are clear these associations are not yet scientific certainties and require greater examination.
But how do we explain this? Some doctors think this association maybe caused by the high temperatures preventing us from sleeping well at night — remember that one element of good sleep hygiene is keeping your bedroom cool, dark and quiet. Others believe that high temperatures discourage people from going outdoors or exercising, which have positive effects on our mood. The hot weather may lead to dehydration and reduced appetite, and in the most severe cases, cause heat stroke and exhaustion requiring medical aid.
No wonder extreme heat can affect our mood.
Regardless, it is clear that more research needs to be done to explore this association of extreme heat and potentially negative mood changes, given that it has been forecast that Canada and many other countries can expect warmer weather in the years to come. In fact, Environment Canada has issued a heat warning for much of the province including the GTA, where we can expect daytime high temperatures of 30 to 35 C, with it feeling more like 40 to 45 C with humidity.
Given all this, it might be a good idea to stay relatively cool and check in on each other, and not just for the usual concerns of heath stroke, cramps and exhaustion, but also for mental health wellness. Check in with your family and friends until this heat wave simmers down.
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