This guest blog was contributed by Christopher Eccleston is Professor of Medical Psychology at the University of Bath, and the author of ‘Embodied: the psychology of physical sensation’.
Winter’s approach reminds us that staying warm is a challenge. In 2014-2015, in England and Wales alone, there were 36,300 preventable winter deaths due to cold exposure among people age 75 and over. We survive in a narrow core bodily temperature range of only a few degrees – human core temperature is around 37ᵒC, we dip into hypothermia at 35ᵒC and hyperthermia is not far above core temperature – and have to keep within the range when the world outside our bodies is more extreme. Even in England, temperatures have been as low as -26.1ᵒC and as high as 38.5ᵒC.
So how do we make the potentially life-or-death decisions that help us stay warm?
Maintaining core temperature within the safe range is down to two systems, one physiological and the other behavioural. The former, thermoregulation, protects us by constantly balancing heat preservation and loss. A control centre in the brain receives signals about temperature changes from sensors deep in the body and near the surface and triggers responses, such as sweating or shivering, to return us to core temperature.
It’s behaviour that can get us into trouble. Awareness of being too hot or too cold lends a hand to our physiology. We make lots of small decisions: do I put on a hat when I am cold or take off my coat when the sun comes out? We can think of dressing as “secondary thermoregulation”, but we don’t always behave in line with the laws of thermal regulation. The truth is that our judgement of the threat to our core temperature is often unreliable and consequently our planning is poor.
It is not the extreme outside temperatures that matter. We tend to spot those and behave accordingly. It is the small changes in temperature, the sudden drops. I recently interviewed Euphemia Graham, who lives with Reynaud’s Phenomenon. Often triggered by cold temperatures, the condition blocks blood supply to our fingers and toes resulting in numbness, pain and risk of injury. Like many people with Raynaud’s, Euphemia is an expert at dressing, at the thermal properties of clothing and at judging external temperature.
As with most of our physical sensations, the decisions we make about temperature are under the control of immediate influences, such as how we feel now. Trusting in the less immediate, often abstract, idea of what we might feel like in the future can be difficult to do; advice is harder to heed. My grandmother used to tell me to take my coat off indoors because ‘I would not feel the benefit’ when going outside. She was right. Such advice works because it is presents a rule to follow, rather than making a decision on how you feel in the immediate moment.
We need more understanding of how people experience their bodies in everyday environments and the behavioural responses that are triggered. Euphemia knows that when it comes to clothing, thinking beyond the immediate, and planning, are what matters. Small decisions can be important. As part of a suite of interventions to tackle preventable winter deaths, we could do worse than listening to our grandmothers.