The UK's relationship with heat is increasingly complicated. Heatwaves that would once have been exceptional are becoming more frequent, and the country's housing stock – designed for cold and damp – is often poorly suited to keeping people cool. Understanding how the body actually manages heat, and knowing when to take it seriously, is useful knowledge for anyone who wants to stay well through summer.
How the Body Manages Heat
The human body maintains a narrow core temperature range of around 36.5–37.5°C. When external temperatures rise, the body has two primary cooling mechanisms: sweating (which cools as sweat evaporates from the skin) and vasodilation (widening the blood vessels near the skin's surface to radiate heat outward). Both mechanisms work well in moderate heat but place significant demands on the cardiovascular system – the heart works harder to push blood to the periphery, and the body can lose significant fluid and electrolytes through heavy sweating.
In TCM, this process is understood as the body's Yang Qi working to manage external heat. The Spleen and Stomach must also work harder in summer to transform and transport food and fluids, which is why digestion is often more sensitive in hot weather. The Heart – the season's primary organ – governs blood circulation and is at the centre of the body's heat management effort.
Hydration: The Foundation
Adequate hydration is the single most important factor in heat safety. Thirst is a late indicator of dehydration – by the time you feel thirsty, the body is already mildly dehydrated. In hot weather or when physically active, drinking water before the sensation of thirst is the most reliable approach.
Electrolytes matter as much as fluid volume. Sweating depletes not just water but sodium, potassium, and magnesium – all essential for normal cellular function. Plain water replaces the fluid but not the electrolytes; in extended heat exposure or heavy sweating, adding a pinch of sea salt and a squeeze of lemon to water, or consuming electrolyte-rich foods (coconut water, cucumber, melon, leafy greens), may help prevent the fatigue, headache, and cramping that electrolyte imbalance can produce.
In TCM, the ideal summer drink is warm or room temperature, not ice cold. Cold drinks are thought to shock the Spleen and Stomach, impairing their function. This doesn't mean avoiding cold water entirely – it means that the habit of drinking very large quantities of iced water may not be as beneficial as it seems, and that cool (rather than ice-cold) drinks are a reasonable middle ground.
Protecting Yourself From the Sun
Sun exposure is both beneficial and potentially harmful. The body requires sunlight for vitamin D synthesis (inadequate in the UK for much of the year), and light exposure regulates the circadian rhythm and supports mood. But unprotected exposure to strong sun – particularly between 11am and 3pm – causes real damage: skin ageing, DNA damage in skin cells, and the risk of melanoma, which remains the most serious form of skin cancer.
A practical approach to sun: aim for 10–20 minutes of direct, unprotected sun on arms and face in the morning or later afternoon (avoiding the peak hours) to support vitamin D synthesis, then protect skin with clothing, shade, and broad-spectrum SPF 30+ sunscreen for longer exposure. Reapplication every two hours (and after swimming or sweating) is essential – a single application is not protective for the whole day.
Recognising and Responding to Heat Exhaustion
Heat exhaustion is the body's warning that it is struggling to cool itself. Symptoms include heavy sweating, cool and pale or damp skin, fast but weak pulse, nausea, headache, dizziness or light-headedness, muscle cramps, and fatigue. The appropriate response is immediate: move to a cool place, lie down with legs elevated, remove excess clothing, sip cool water, and apply cool damp cloths to the skin. Most people recover within 30 minutes with this approach.
Heat exhaustion that is left untreated or in very vulnerable individuals (the elderly, young children, those with chronic health conditions) can progress to heatstroke – a medical emergency. Heatstroke involves a body temperature above 40°C, confusion or loss of consciousness, and may involve hot dry skin (if the sweating mechanism has failed). This requires immediate emergency care – call 999.
Cooling the Home
Keeping the home cool during a heatwave requires active management of airflow. The most effective approach in a UK home without air conditioning: keep windows and curtains closed on the sunny side of the house during the day to block heat gain; open windows on the shaded side to allow cross-ventilation; open windows fully in the evening once outside temperature drops below indoor temperature. A fan creates air movement but does not cool a room – it cools the body through evaporation, so should be directed at people rather than used to circulate hot air.
The bedroom deserves particular attention. Sleeping with a cool damp cloth over the feet, using natural fibre bedding (cotton and linen breathe better than synthetic materials), and lowering the body temperature with a cool shower before bed may all make a meaningful difference to sleep quality through summer.
Those Most at Risk
Older adults, young children, pregnant women, and those with chronic health conditions (particularly cardiovascular, respiratory, or kidney conditions) are most vulnerable to heat-related illness. Many medications – including diuretics, blood pressure medications, and certain antidepressants – impair the body's heat regulation. If you or someone you care for falls into these categories, the practical cooling measures above are particularly important to follow during hot spells, and a GP or pharmacist should be consulted about whether any medication may need to be managed differently in the heat.