Does very hot weather leave you feeling more exhausted and lethargic than usual? There might be an initial surge of joy when the sun finally comes out – but once temperatures really creep up, we can end up feeling physically drained, wondering whether we should follow the Mediterranean’s lead and start introducing daily siestas. So, why does hot weather make us so tired? We asked a doctor to explain… Our bodies have to work harder in the heat “When the weather is hot, our bodies have to work harder to cool themselves down,” says Dr Zulqarnain Shah, medical director at SSP Health and GP at SSP Health practice Colne Road Surgery. “The body’s natural cooling mechanism involves increasing blood circulation near the skin’s surface and promoting sweat production. These physiological changes can lead to fatigue and a feeling of lethargy. It is essential to recognise that this fatigue is a normal response to heat and is typically temporary.” Dehydration Low energy and tiredness are also common when you’re lacking hydration. “Hot weather increases the rate of fluid loss through sweating, leading to dehydration. Dehydration can contribute to fatigue and make you feel even more lethargic,” adds Dr Shah. “To avoid this, it’s important to stay adequately hydrated by drinking plenty of fluids, especially water. Aim to drink even when you’re not feeling thirsty, as thirst is not always an accurate indicator of dehydration.” Heat exhaustion “Prolonged exposure to heat can result in heat exhaustion, a condition characterised by symptoms such as heavy sweating, weakness, dizziness, nausea, headache, and muscle cramps. If you experience these warning signs, it’s crucial to move to a cooler environment, drink fluids, and rest. If symptoms persist or worsen, seek medical attention promptly,” says Shah. It’s important to pay attention to warning signs, as if heat stroke develops, this is a medical emergency. Shah stresses: “Heat stroke is a severe and potentially life-threatening condition that requires immediate medical intervention. It occurs when the body’s temperature regulation fails, and the core temperature rises dangerously high. “Symptoms may include a high body temperature (above 39.4C), altered mental state, confusion, rapid breathing, rapid heartbeat, and even loss of consciousness. If you suspect heat stroke, call emergency services immediately.” Sleep deprivation The extra tiredness could also be linked to poor sleep, as this can really suffer in the heat. “Hot temperatures can disrupt sleep and lead to poor sleep quality. The body needs to cool down to initiate sleep, and the excessive heat can make it difficult to reach the optimal sleep temperature,” explains Shah. “To improve sleep in hot weather, consider using fans or air conditioning, wearing lightweight and breathable sleepwear, keeping your bedroom well-ventilated, and using lighter bedding.” Pre-existing conditions could get worse Many people living with chronic or long-term health conditions deal with fatigue, which may flare up during heatwaves. “Hot weather can exacerbate symptoms and increase fatigue in individuals with certain chronic health conditions. Conditions such as heart disease, kidney problems, and respiratory issues can be particularly sensitive to heat,” notes Shah. “It’s vital to be aware of your specific health condition and consult with your healthcare provider for personalised advice on managing your symptoms during hot weather. They may recommend staying in cooler environments, adjusting medications, or monitoring your fluid intake more closely.” Read More Airbnb customer furious after being charged extra over dog hair People seek hay fever advice once every three seconds, says NHS England Why is my hay fever so bad at the moment?