What cause a twitching eye?
While we’re on the subject of twitching, you may wonder why your eye sometimes twitches (or perhaps you’re more concerned about it being noticeable to others). The twitch itself occurs due to the repetitive contracting and relaxing of the muscle below the eye as it is stimulated by a repetitive electrical impulse from a nerve. But as to why the nerve should fire in this way when we are tired or stressed remains a mystery. Why are yawns contagious? Whether it’s laughing or yawning, human bodies seem to have an amazing capacity for infectious behaviour. But why is it that, when we yawn, the world tends to yawn with us? The traditional explanation for yawning is as the result of reduced oxygen levels in the brain but newer theories claim that it is a trigger for changes in ‘brain state’ in preparation for a demanding activity such as a marathon or exam. Why yawning should be so infectious is harder to pin down – the evolutionary explanation seems to be that collective yawning acts as warn
