A skin specialist is urging people across east London to be sensible during the current heatwave.

Dermatologist Dr Jane McGregor says moderate exposure to the sun will make sure people don’t suffer in the sun.

She said: “In this sort of heat there are problems, skin burning and blistering with the prospect of skin cancer in the long term.

Then there are the systemic effects - headaches, flu like symptoms, dehydration, and in extreme cases, death.”

Dr McGregor, who works at The Royal London Hospital in Whitechapel, said the effects are worse for those with fair skins but everyone can suffer from systemic effects when the body’s vital functions can be compromised.

She said: “Children and babies are particularly affected because their skins are more sensitive and their skin has not thickened as much (as adults). Older people are more prone to systemic failure.

“I take the view that moderate and sensible exposure to the sun can result in a feeling of wellbeing and can increase production of Vitamin D but you don’t need to be in the sun for long. 10-15 minutes is enough.”

She says children should make sure they drink enough water while everyone can benefit from staying in the shade as that can reduce sun exposure by 30 to 50 per cent.

Meanhile, researchers at the University of East London have discovered that people who drank a pint of water before conducing mental tasks had reaction times that were 14 per cent faster than those who did not have a drink. The effect was more noticeable in people who were already thirsty, apt during the hot weather.

Dr Edmonds, senior lecturer in UEL’s School of Psychology, who led the study, working with colleagues at the University of Westminster, asked 34 volunteers to perform a range of mental activities after a night of not drinking any fluid. Before each test they were given a cereal bar and either a pint of water or just a cereal bar alone.

Dr Edmonds said: “Reaction time seemed to be most affected by water, particularly if the people were thirsty. It might be because when you are thirsty, it diverts your attention away from the task at hand. This would be important for people in situations where concentration is key.

“There are also hormonal theories about how dehydration affects the brain and it is possible that water is fixing an imbalance there too. Around 80 per cent of the brain is water, so it is clearly important to make sure it gets enough.”