It’s officially cold and flu season. The average adult suffers between two and four a year – most of which will be creeping up around now.
And many will notice that the much-hated sniffles, muscle aches and sore throat feels much worse after sundown. Now, experts have revealed exactly why that is.
There are several reasons, they say. But mostly, the answer lies with the body’s circadian rhythm – or internal body clock.
Just about every bodily function is programed to operate to its full capacity at certain times in the day, and wind down at others.
It is a well-known phenomenon that cold and flu symptoms get worse at night, and this is mostly due to the body’s internal clock
For instance, when the sun sets and the body detects sleep time is approaching, the brain releases fewer stress hormones like cortisol, and tells the gut to slow digestive processes.
But certain immune cells become more active. These cells are designed to hunt down and destroy pathogens like viruses.
This ‘fight’ triggers inflammation – an evolutionary tool that kills bugs but is also responsible for the tell-tale cold symptoms.
‘Immune cells can cause irritation and inflammation, which ends up making respiratory symptoms worse at night,’ Dr Diego Hijano, a pediatric infectious disease specialist at St. Jude Children’s Research Hospital, told the New York Times.
Immune cells become more active at night, fighting the virus and triggering the dreaded cold and flu symptoms
The drop in stress hormones like cortisol can worsen the problem, as the chemical can effectively calm inflammation.
Experts also highlight another important factor: simply, cough and cold symptoms are worse when you’re lying down.
This is because mucus starts to pool at the back of your throat – a problem which doctors call postnasal drip.
‘Throughout the day, the accumulation of mucus is less of a problem because gravity helps drain it when you are upright and moving around,’ said Dr. Juan Chiriboga-Hurtado, a family medicine specialist at Keck Medicine of the University of Southern California.
Finally, there’s the lack of distraction at night which forces you to focus on the irritating cough you can’t shift.
So what can you do to achieve a decent night’s sleep?
Experts recommend simple things, like drinking plenty of fluid throughout the day to thin mucus, and using a nasal saline spray to clear some of the sticky liquid.
Others suggest using menthol-flavoured cough lozenges — or throat sprays — to provide a cooling sensation to the throat and help beat the irritating tickle.
But there is no use in trying not to cough.
‘There is no benefit in trying to suppress a cough since the reason you’re coughing is because the body perceives it needs to get rid of some source of irritation,’ says Dr Anindo Banerjee, a respiratory consultant working in a UK hospital.