Winter blues and runny noses: how cold temperatures impact health

That strange feeling of a high fever yet low body temperature, aching limbs, and a runny nose – you’ve guessed it, it’s the flu. The onset of the flu begins as surely as temperatures decrease, the seasonal dropping of leaves in autumn, and as consistently as we check our bank accounts, yet scientists remain perplexed as to the link between chilly temperatures and an influx of influenza.

Over recent years, it has become apparent that it is not solely down to the colder weather that flu season occurs yearly – rather, how our sneezes linger in the air. Globally, influenza affects up to 5 million people each flu season. Although vaccines are available, their effectiveness remains restricted as antibodies fail to recognise the ever-changing viral antigens and so immunity is lost. 

The laws of thermodynamics offer a handy explanation for the emergence of the flu each season. Cold air carries less water vapour, reaching a “dew point” at which it falls as rain. As the air is drier, moisture is lost more rapidly, which creates a favourable environment for the flu virus to blossom. Scientists at Columbia University found, almost always, the flu epidemics follow a drop in air humidity. Droplet transmission, from our coughs and sneezes in dry air, breaks into smaller pieces – so small they remain afloat for several hours and even days. The cold air in winter months provides an amalgamation of dead cells, mucus, and viruses from strangers, friends, and family members. Maybe mask-wearing wasn’t so bad after all?

The physical effects of winter weather on the body are largely discussed and yet consideration of our mental health remains overlooked. Seasonal affective disorder (SAD) – it’s a thing! 

More than 2 million people in the UK and more than 12 million people across Northern Europe suffer from SAD. In November we receive roughly 9 hours of daylight on average, compared to 16 hours in July. Such has a significant impact on our neurophysiology. Reduced exposure to sunlight prevents the hypothalamus in the brain from functioning properly – impairing the production of serotonin. Serotonin is commonly dubbed the “happy hormone”, so a reduction in its production leads to feelings of depression. Therefore, it’s not just Lemsip or Sudafed we need to stock up on – rather lunchtime walks and regular exercise can equip our arsenal to help us tackle the winter months ahead. 

As clocks turned back on the 30th of October, with many welcoming an extra hour in bed, scientists warned that this wreaks havoc with our sleeping pattern, leading to an increase in cardiovascular diseases and mental health issues.  Our circadian rhythm: the mental, physical, and behavioural changes that follow our 24-hour cycle, is influenced primarily by sunlight and darkness. As clocks change bi-annually, this results in a whole host of problems for people globally. A study published in The Sleep Medicine Journal found stroke rates to be 80% higher in the immediate days preceding the changing of the clocks. Whilst further research published in The Epidemiology Journal showed a link between the clocks changing and depressive episodes, with changes in our circadian rhythm linked to SAD. It is more important than ever to maintain a healthy sleep schedule, keeping our bodies in check to take on the winter months. 

Britain reportedly has one of the worst winter death rates in Europe, with 25,000 elderly people dying prematurely from cold-related illnesses each year. This serves as a chilling reminder of how the cold affects our elderly population. Ageing harbours a plethora of effects on the immune system: from reduced production of B and T cells in the bone marrow and thymus, to dampened functional capacity of mature lymphocytes in secondary lymphoid tissues.

On a positive note, biotechnology has allowed for recent advancements in the identification of biomarkers. Such helps to define ageing profiles, and therefore allows for a more personalised approach for targeted interventions within the elderly population. This winter may not be so bleak!

From a public health perspective, in the post-pandemic era we currently find ourselves in, we are prepared to tackle and mitigate the impact of viruses. As we can see viruses are constantly changing, but the dynamism and adaptability of the population today makes for a great battalion this winter. Now more than ever, it’s important to look out for each other, winters can be tough but coming together makes for easy work! 


Image: Annie Spratt on Unsplash

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