In the wake of a recent BBC Education News story on the NASUWT teachers' union survey showing that one in three teachers have had to give lessons in classrooms with temperatures over 30 degrees, researchers at the Universities of East London and Westminster have some good news for exam candidates worried about their performance in overheated examination halls.
They observed 447 psychology students at various levels at the University of East London during examinations, and noted that just a quarter of them entered the exam hall with a bottle of water.
They also found that the more mature the student, the more likely they were to bring in water.
Researchers then looked at examinees' coursework grades and found that in an examination environment, foundation students who drank water were likely to see their grades improving by up to 10%, while first-year students could expect an improvement of 5%, and second-year students could see an improvement of 2%.
Across the range of students who drank water, the average improvement in marks was 4.8%.
The research paper recommended younger students in particular should be informed about the importance of remaining hydrated in exam situations.
While it's true that dehydration can impair brain functionality, Dr Chris Pawson, from the University of East London also thinks drinking water can lessen exam nerves.
He says: "Future research is needed to tease apart these explanations, but whatever the explanation it is clear that students should endeavour to stay hydrated with water during exams."