Medical Matters Muiris Houston Don't knock the weather - without it how would we start conversations? (Anon)
Thanks to the recent bad weather - according to Met Éireann it has been more than a month since the country has had a day without rain - there has been no difficulty starting conversations in shops and in surgeries. "Isn't the weather awful, wouldn't it get you down?" has been a frequent conversation opener.
As measured by anecdotal evidence from primary care consultations, bad weather in summer appears to cause greater upset than storms or snow in winter. People's mood is adversely affected; it is not uncommon for patients to say that unseasonable summer weather is making them feel depressed.
During one summer in the 1990s, when the weather was consistently bad from June through to August, I recall a particular week when the collective resolve of patients in the practice crumbled. It was around mid-August and for the best part of a week, patient after patient consulted because they were feeling down, tired and irritable. Many related their feelings to the sustained period of rain and lack of sunshine; and, while none were clinically depressed, they were certainly experiencing a mood dip.
It seems that rather than causing frank depression the poor weather upsets our collective expectation that this time of year should be dry and sunny. Scientists speak of the importance of anticipation as part of the natural rhythm of life, including seasonal change. This deep anticipation tunes us into our broader environment. According to François Jacob, a pioneer of molecular biology, "one of the deepest, one of the most general functions of living organisms is to look ahead, to produce future".
So in psychological terms, is it possible this lack of fulfilment of meteorological expectation leads to a form of adjustment reaction, a recognised mood disorder? Triggered by the stress of unmet anticipation of a good summer, some of us begin to feel down and irritable.
Despite the intuitive common sense of such an explanation, and the obvious alteration of mood triggered by our poor summer, there is little scientific evidence for a link between mood and weather.
However, a 2002 study by researchers at the University of Michigan found that pleasant weather improved mood and memory and increased creative thoughts as the time spent outside increased. Some 600 participants were randomly assigned to be either outdoors during good weather, outdoors in dull weather or spend their time indoors. In order to control for the positive benefits on mood of exercise, all three groups exercised during the experiment. Results showed those who spent their time outdoors during warm or sunny days showed improved mood and memory compared to the other two groups.
For the weather to improve mood, the
subjects needed to spend at least 30 minutes outside in the sun. Interestingly, the researchers found that spending time indoors on warm and sunny days actually caused a dip in mood and creativity.
They also discovered that the optimal temperature for mood is 72 degrees Fahrenheit, about room temperature; there were regional variations however, with mood peaking at 65 degrees in Michigan and 86 degrees in the warmer climes of Texas.
This finding suggests that what we perceive as a pleasant day depends to some extent in where we live and the "normal" weather for that location.
The authors were at pains to point out that the effects of weather on mood were "not huge", but were significant. And they say that the impact of weather on mood and cognition can be difficult to demonstrate because people living in industrialised countries spend 93 per cent of their time indoors.
Separate research has found a connection between hot weather and violent behaviour. Hot, humid days appear to be the worst, causing sleeplessness, irritability, lethargy and poor reaction times and performance. The symptoms may be linked to oscillations in atmospheric pressure.
Readers will be familiar with the condition Seasonal Affective Disorder (SAD), which is reckoned to affect 3-5 per cent of the population. Typically patients with SAD will experience lethargy, weight gain, sleepiness and low mood as the light begins to fade with the onset of winter.
However, a summer version of SAD, also known as Reverse Seasonal Affective Disorder has also been described. It is unclear what triggers the summer version, but some experts claim it is a sensitivity to either too much heat or too much light. But no link has been established between weather patterns and either version of SAD.
And even the health of the stock market is influenced by the weather. Research has shown that sunny weather causes stocks to rise while Marks and Spencer's last week announced that growth at the high-street retailer had ground to a halt. The reason? A slump in sales of summer clothes as a result of our unseasonably wet and cold weather.
Dr Muiris Houston is pleased to hear from readers at mhouston@irish-times.ie but regrets he cannot reply to individual medical queries.