Experts reveal why your cold is always worse at night – and offer tips to stop you coughing in bed

It’s officially cold and flu season. The average adult suffers between two and four per year, most of which are now creeping around.

And many will find that the hated sniffles, muscle aches and sore throats feel much worse after sunset. Now experts have revealed exactly why that is.

There are several reasons, they say. But usually the answer lies with the body’s circadian rhythm, or internal body clock.

Almost every bodily function is programmed to work at full capacity at certain times of the day and to relax at other times.

For example, when the sun sets and the body senses that sleep time is approaching, the brain releases fewer stress hormones such as cortisol and tells the intestines to slow down digestion.

But certain immune cells become more active. These cells are designed to detect and destroy pathogens such as viruses.

This ‘fight’ causes inflammation – an evolutionary tool that kills insects, but is also responsible for the telltale cold symptoms.

‘IImmune cells can cause irritation and inflammation, worsening respiratory symptoms 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 causing the dreaded cold and flu symptoms

The drop in stress hormones such as cortisol can worsen the problem, as the chemical can effectively calm inflammation.

Experts also emphasize another important factor: cough and cold symptoms simply get worse when you lie down.

This is because mucus starts to build up in the back of your throat – a problem doctors call postnasal drip.

“During the day, mucus buildup is less of a problem because gravity helps drain it as you stand up and move,” says Dr. Juan Chiriboga-Hurtado, a family medicine specialist at Keck Medicine of the University of Southern California .

Finally, there’s the lack of distractions at night, forcing you to focus on the irritating cough that you can’t shift.

So what can you do to achieve a good night’s sleep?

Experts recommend simple things like drinking plenty of fluids throughout the day to thin the mucus, and using a saline nasal spray to remove some of the sticky fluid.

Others suggest using menthol flavor cough lozenges – or throat sprays – to provide a cooling sensation in the throat and help beat the irritating tickle.

But there’s no point in trying not to cough.

“There’s no point trying to suppress a cough because the reason you’re coughing is because the body senses that it needs to get rid of a source of irritation,” says Dr. Anindo Banerjee, a respiratory consultant who works in a British hospital.