Eight Glasses a Day MakeS the Doctor Stay?

By Alexander Pan

Drinking eight glasses of water a day against your own thirst signals can lead to water intoxication or hyponatremia, which results from the critically low sodium levels in the body. Symptoms of over-drinking include lethargy, convulsions, nausea, and a possible coma. Researchers at Monash University uncovered ‘swallowing inhibition’, which is a mechanism that the brain uses to prevent over-drinking. Usually, this brain mechanism initiates the ‘swallowing reflex’ as a physical resistance to prevent excess water intake. Functional magnetic resonance imaging (fMRI) was used to measure activity in the brain to observe how swallowing inhibition works. The researchers discovered increased activity in the frontal cortex of the brain when subjects drank more than they need to. This increased activity shows that the subjects were trying to resist the swallowing inhibition brain signals by forcibly drinking more than they had to. Another experiment from Monash University tested the resistance to drinking water of one group that exercised beforehand compared to the other group that was persuaded to drink excess water. The 3-fold increase in resistance to drink water from the 2nd group shows the ‘swallowing reflex’ mechanism of water regulation in action. So then what is the standard amount of water that everyone should drink every day? That all depends on each individual person! Associate Professor Farrell states, “just drink according to thirst rather than an elaborate schedule.” Staying healthy depends on the individual’s decision to satisfy his thirst levels without under or over-drinking. 

Pascal Saker, Michael Farrell, Gary Egan, Michael McKinley, and Derek Denton. Overdrinking, swallowing inhibition, and regional brain responses prior to swallowing. Proceedings of the National Academy of Sciences, 2016;