It's often seen as nothing more than whinging about a cold, but 'man flu' really does exist, according to research.
Men suffer more with coughs and colds because they have extra temperature receptors in the brain and so experience worse symptoms.
Children deal with colds the same way because the relevant area of the brain is the same size in boys and girls, said Durham University neuroscientist Dr Amanda Ellison.
But when boys hit puberty testosterone starts to act on the area, called the preoptic nucleus, making it larger.
"When you have a cold one of the things that happens is you get an increase in temperature to fight off the bugs," Dr Ellison said.
"The bugs can't survive at higher temperatures.
"When your immune system is under attack the preoptic nucleus increases temperature to kill off the bugs. But men have more temperature receptors because that area of the brain is bigger in men than women.
"So men run a higher temperature and feel rougher - and if they complain they feel rough then maybe they're right."
Research published in 2009 which also supported the existence of man flu was criticised as inconclusive as it related to genetically engineered mice rather than humans. But Dr Ellison's study was based on research carried out on human brains.
"It is part of the whole argument about the differences between men and women and how their behaviour can be influenced by differences in their brains," she added.
Commenting on the fact that her findings could be seen as controversial, Dr Ellison said: "I'm just throwing it out there. The debate will rage on and quite rightly so. The trouble with man flu has always been that there is not much hard evidence that the feelings are worse in males than in females. This is just a possible cause."
- DAILY MAIL