Ready for action: Cold remedies
Any increase in the number of blocked noses and colds could well be due to the increased pressures of modern life, they say.
One expert even believes that the events of 11 September may lead to more colds and flu this year as the threat of terrorist attack adds to the general burden of winter worries.
A healthy immune system is key to fighting off the plethora of microscopic adversaries that seem to crowd in on society as the days shorten.
The body is ready for short-term stress - a sudden, nasty surprise evokes the traditional "fight or flight" response, and the release of stress hormones such as cortisol.
However, if this continues over a sustained period of weeks, this defence mechanism gradually turns into an enemy.
On the lookout
Professor Phil Evans, from the University of Westminster, says: "If this stress is chronic, one of the effects is that the high circulating levels of cortisol compromise certain areas of the immune system.
"One of the area we believe is particularly affected is protection against early infection.
"These are the immune cells which look out for foreign bodies that are within cells - such as viruses."
Viral infections which lie dormant in the body - such as herpes virus, which in some forms can cause cold sores - tend to re-emerge in response to chronic stress, adding weight to the links between stress and immunity.
Not only is there a link between stress and infection itself - but also between stress and the severity of the infection.
However, although it might be plausible that stress makes it harder shake off infections, there is little scientific evidence to back this.
The job of the immune system is not simply to deal with invaders - in recent years scientists have uncovered far more evidence that it plays an important role in keeping far more sinister conditions at bay.
Immune cells may also be supposed to identify and destroy human cells which have gone haywire - before they can produce a cancer.
Professor Evans said: "We know that chronic stress has an effect on the part of the immune system which looks for viruses hiding in cells - it may well also be the part which looks for other irregularities within the cells."
Up the nose
Psychologist Professor Andy Smith, from the University of Wales at Cardiff, says that the precise mechanism by which stress undermines the immune system has yet to be uncovered.
"It's possible that the stress hormones themselves may alter what happens here," he said.
But he said it was undeniable that chronic stress could have a pronounced effect on the likelihood of humans picking up infections.
"We know that stress influences the immune system in very many ways ."
Time of year
If today's society is genuinely more continually stressful than previous models, then it is likely that the number of working days lost to innocuous viruses will rise.
Professor Ron Eccles, from the Common Cold Centre at the University of Wales, says that the cramming of our cities may also be partly to blame.
"I don't think we have ever been so squashed together," he said.
"We're much more likely to pick up colds - we're being bombarded with viruses all the time.
"Our lifestyle is much more stressful."
He said that since 11 September he had heard anecdotally of an upsurge in people heading for GP consultations.
"People are generally more anxious - I would not be surprised if there was an increase in the level of viral infections this year as a result."
However, the unseasonably mild autumn has left Professor Eccles still awaiting the traditional increase in colds and flu which accompanies the first weeks of chilly weather.
It's only then that the true impact of our stress-filled lives will become apparent.