WHY WE FEEL SO TIRED WHEN IT’S HOT AND HOW TO KEEP ENERGY LEVELS UP IN A HEATWAVE (NO CAFFEINE REQUIRED)

Hands up if you’re feeling more tired, sluggish and lethargic than ever? We wait all year for a warm spell and then, when the heatwave hits, we can barely function. And with the mercury set to soar this week to 30°C, lots of us will be wondering how we’ll ever get through our growing to-do lists. Afternoon slumps are pretty normal but in the heat, exhaustion can be debilitating.

The tiredness the intense summer heat brings is not just extremely inconvenient, but it can get in the way of our day-to-day lives and routines. So why do we get so tired in the heat and what can we do to stay alert when it’s sweltering outside?

“Staying cool requires energy, and a lot of it,” Dr Sam Watts, founder of Mind Body Medical, tells Stylist. “When our body temperature begins to rise, the brain mobilises a cascade of responses within the body to help cool us down. All of these responses require energy, which means there are fewer resources to supply other areas of the body, such as our brain and muscles, and this can lead to both physical and cognitive lethargy.”

In order to help our normal internal body temperature stay at 37°C, the body increases its blood flow to the skin’s surface to release heat and creates sweat to keep our skin cool when it evaporates, all of which depletes us of huge amounts of energy. Other factors, including the body repairing damage from sunburn and dehydration, also make us feel tired.

So, what can we do to beat the heatwave tiredness and keep our energy levels up if we don’t have the benefit of air-con? It’s worth flagging here that heatstroke is a really serious condition that should be treated as an emergency. Call 999 if someone has signs of heatstroke, which include: fast breathing or shortness of breath, a fit (seizure), loss of consciousness or they are not responsive. 

How to sustain energy levels in the heat 

Drink up

Dehydration is common in hot weather as we perspire more to cool ourselves down; however, loss of water can prevent us from carrying out normal body processes and make us feel sluggish.

“The first and most important way of maintaining concentration and energy levels in the heat is to stay optimally hydrated,” explains Dr Watts. “Even a small drop in hydration, as facilitated by increased sweating, will result in a reduction in concentration and heightened levels of fatigue.”

Therefore it’s vital we drink enough water. 

“The best way to test this is to ensure that your urine is no darker than a pale-straw colour and that there is no odour; if this is not the case, aim to up your fluid intake.”

Pay attention to electrolytes 

Electrolytes have a natural positive or negative electrical charge when dissolved in water and help the body with all sorts of processes including regulating chemical reactions and maintaining the balance between fluids inside and outside cells. 

“An increased rate of sweating, as experienced by virtually everyone when it is hot, can very quickly lower our levels of essential electrolytes,” explains Dr Watts. “This, in turn, can induce fatigue and poor concentration very quickly.”

To prevent this, Dr Watts suggests eating plenty of high electrolyte foods such as kale, broccoli, beans, almonds, spinach, pure coconut water or a sports electrolyte drink if you are exercising for more than 30-minutes a day during the hot weather. 

Eat cooler, lighter meals

“Try swapping heavy meals for lighter plates when it gets hot outside. “Consuming heavy meals in the heatwave can contribute to low energy levels as the body works extremely to burn the extra calories and lower the high internal temperatures,” says Ieva Kubiliute, wellness psychologist at Oliolusso.

Swapping heavy meals for lighter ones also speeds up digestion, which can make us feel energetic. 

Stay cool 

It sounds obvious, but doing all you can to make your body cooler so it doesn’t have to work as hard is one of the best things you can do to stay alert in the heat. 

“All of the cognitive and physiological responses to heat come from being too hot,” says Dr Watts. “Very often we can prevent this by staying out of the sun, exercising earlier or later in the day, ensuring our work and living spaces are kept cooler by fans or air conditioning and using cold showers and baths to help reset our inner thermostat.” 

Images: Getty

2025-06-30T12:48:12Z