Swansea University study finds dehydration affects mood
Becoming slightly dehydrated can have an effect on mood, memory and attention, according to Swansea University research.
An article published in the American Journal of Clinical Nutrition found a reduction of 0.6% of body mass through water loss can affect people's abilities.
The study tested participants' mood and memory after sitting in a heated room.
It was carried out by the university's college of human and health sciences.
Previous research found a loss of 2% can affect ability to function properly - but this typically applied to athletes undergoing extended periods of activity or someone who has gone without fluids for some time.
The latest research focused on much lower levels of water loss people experience in day-to-day life.
The mood and memory of participants was tested before and after sitting in a room heated to 30 degrees Celsius (86 degrees Fahrenheit) for four hours.
"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," said Prof David Benton.
"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."
Dr Benton said it was important people keep hydrated during the warm summer months, especially children who lose water quicker and are reliant on adults giving them drinks.