Going on a long car journey? Ensure you take a pee.

That is the warning from a group of Melbourne researchers who have discovered that a full bladder can be as distracting to a driver as major sleep deprivation or drinking alcohol

According to Caulfield Hospital’s aged psychiatry research coordinator Dr Matthew Lewis, a full bladder has a negative effect on attention and memory.

In other words, riding in a car with a teetotal driver who has forgotten to urinate can be just as dangerous as travelling with a tipsy driver, or someone who has been awake for 24 hours.

The study, published in the Neurology and Urodynamics journal, also reveals that a full bladder can reduce the speed at which drivers make decisions.

The research won an Ig Nobel prize, which recognises the weirdest scientific breakthroughs that first make people laugh, and then make them think.