Previous research within this field has found a loss of upwards of 2% of body mass through water loss leads to noticeable effects on your ability to function properly. 

This would typically apply to athletes undergoing extended periods of activity, or someone that has gone without fluids for several days.

This new research has gone one step further, looking at how we may be affected by much lower levels of water loss, which we’d all experience in day-to-day life. 

‌Commenting on the study, Professor Benton said: “Roughly 60% of our body is made up of water, and this level is continually fluctuating, largely due to water loss through urine and sweat.

“Our research found that when losing only 0.6% of our body mass, there were noticeable effects on an individual’s memory, attention and mood.”

The study tested participant’s memory and mood before and after sitting in a room heated to 30°C for four hours, and found a direct correlation between the change in a subject’s hydration level, and how well they performed in memory and mood tests.

The study, which picked up body mass levels accurate to within 5g, found participants became less happy and felt that tasks presented to them would be harder to achieve, as their water levels reduced.

‌As the population sweltered in temperatures of over 34°C last month and with the summer weather continuing in the low to mid 20’s, Professor Benton said: “It is very important that we all remain well hydrated to ensure we can continue to function effectively, and be able to enjoy the summer weather!  As temperatures rise, it is likely we will lose water at a faster rate, and need to top this up more regularly.

‌“This is particularly important for children, who may be reliant on others to fetch them a drink.  They lose water quicker than adults, as they’ve a higher surface area relevant to their size and tend to perspire more through regular activity. 

“In general, we are a well hydrated nation.  As we get older however, our sense of thirst can reduce, and our kidneys, which manage our hydration levels, can reduce in effectiveness. 

"It’s important, whether we feel thirsty or not, to keep an eye on what we are drinking, and ensure we’ve had enough throughout the day.”

‌Picture:  The research group from Swansea University’s College of Human and Health Sciences (left to right): Alecia Cousins, Hayley Young, Professor David Benton

The European Food Safety Authority (EFSA) recommends men consume 2.5 litres and women consume 2 litres of water per day, via food and drink. 

If you are unsure whether you’ve had enough, the colour of your urine can be a good indication – if it’s clear or light yellow, you are likely to be well hydrated. If it’s a dark yellow or amber, you may be dehydrated and in need of water.

To read more about the study, please visit: http://ajcn.nutrition.org/.