The 2015 study published in Physiology and Behaviour was carried out on a selection of male drivers by the UK's Loughborough University and funded by the European Hydration Institute. Over the course of two days, the drivers were put through an array of tests, including using a driver simulator.
When properly hydrated there 47 driving incidents, but when dehydrated the number of incidents rose to 101. In the study, an incident was defined to include drifting across a lane drifting, late braking, and touching or crossing the rumble strip or lane markings.
According to Ron Maughan, who led the study and is emeritus professor of sport and exercise nutrition at Loughborough University, as well as chair of the European Hydration Institute Science Advisory Board: "The levels of driver errors we found are of a similar magnitude to those found in people with a blood alcohol content of 0.08 per cent, the current UK legal driving limit.
"In other words drivers who are not properly hydrated make the same number of errors as people who are over the drink drive limit."
Above: "A Tall Glass of Water" by Enid Martindale on Flickr.
A 2013 study by University of East London and the University of Westminster, and published in Frontiers in Human Neuroscience, put 34 people through a series of tests a week apart after a night of no drink or food.
The study showed that people who were feeling subjectively thirsty and drank around 775 millilitres or three cups of water before undergoing the tests improved their reaction times by 14 per cent. In one test, though, participants who didn't drink beforehand were better at discriminating between a series of images.
Dr Caroline Edmonds, the study's lead author, told Medical News Today, "This study shows that water can be helpful for cognitive performance, and sometimes it can be helpful to be thirsty - we need to do more studies to find out why".
Above: Modified Nissan Juke with SOAK coating on its seats.
These studies were highlighted recently by Nissan, which showed off the SOAK concept. Made in collaboration with Droog, a Dutch concept design company, SOAK is a sweat-sensing coating that can be applied to the steering wheel and seat covers.
Conceived by Paulien Routs, a designer and researcher at Droog, the SOAK covering was originally meant for clothing, and turns yellow when it's dehydrated and blue when hydrated.
Nissan says it has no plans to put employ the SOAK covering on its future models.
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