Drinking Too Much Water Can Kill You

Drinking too much water may cause potentially fatal water intoxication, claims a new study which has for the first time identified the mechanism that regulates fluid intake in the human body and stops us from over drinking. The study, led by researchers challenges the popular idea that we should drink eight glasses of water a day for good health. It showed that a ‘swallowing inhibition’ is activated by the brain after excess liquid is consumed, helping maintain tightly calibrated volumes of water in the body. If we just do what our body demands us to we will probably get it right – just drink according to thirst rather than an elaborate schedule. The researchers asked participants to rate the amount of effort required to swallow water fewer than two conditions; following exercise, when they were thirsty, and after they were persuaded to drink an excess amount of water.

The results showed a threefold increase in effort when over drinking excess water, which meant they (participants) had to overcome some sort of resistance. This was compatible with our notion that the swallowing reflex becomes inhibited once enough water has been drunk. Researchers used functional magnetic resonance imaging (fMRI) to measure activity in various parts of the brain, focusing on the brief period just before swallowing. The fMRI showed the right prefrontal areas of the brain were much more active when participants were trying to swallow with effort, suggesting that the frontal cortex steps in to override the swallowing inhibition. Drinking too much water puts the body in danger of water intoxication or hyponatremia, when vital levels of sodium in the blood become abnormally low, potentially causing symptoms ranging from lethargy and nausea to convulsions and coma.

Your Yawn May Reveal How Smart You Are

A new study has found that the length of a yawn can indicate how big your brain is, and how many neurons you have. These say researchers, could explain why humans yawn longer than other mammals. The research conducted is based on the fact that animals, such as gorillas, hippos, and elephants – which are bigger than humans but have a proportionately smaller brain – all yawn for a shorter durations than humans. This led to the hypothesis that brain size – rather than head or body size – is likely to yawn length. The researchers scanned YouTube to find a bunch of different animals yawning. In the end, they studied over 205 yawns from 177 individuals across 24 taxa. They found that mice had the shortest yawns, lasting, on average, 0.8 seconds, and humans had the longest, lasting an average of 6.5 seconds. Camels came in second and dogs in third.