At this time of year, it can seem like the half the office is down for the count. Cold viruses are circulating, and whether you catch one depends on a number of factors.
Some things can lower your body’s ability to fight off a cold, leaving you with symptoms like sniffles, fatigue and a cough. Here’s a look at some common culprits.
Lung problems
If you already have problems with your respiratory system, like asthma or chronic obstructive pulmonary disease (COPD), you’re more likely to catch respiratory infections like colds, said Dr. Chris Mody, head of the department of microbiology, immunology and infectious diseases at the University of Calgary’s School of Medicine. This is because the structure of your lungs has changed, so it’s harder to clear the virus.
Fatigue
There have been “pretty definitive” findings about the link between lack of sleep and susceptibility to colds, according to Dr. Michelle Murti, a public health physician with Public Health Ontario.
In one small American study of about 150 people, individuals who slept fewer than seven hours per night were nearly three times more likely to develop a cold when exposed to a virus than people who slept more than eight or more hours.
“So sleep is definitely an important part of keeping healthy overall and may also be an important part of keeping you healthy against things like the common cold,” Murti said.
Importantly, it seems like a few restless nights aren’t going to raise your risk — it’s about chronic fatigue, she said. “Maybe a few sleepless nights are maybe something that you can bounce back from, but maybe a consistent stressful situation might be more difficult to recover from.”
WATCH: What common wisdom should you really believe about the common cold?
Stress
Speaking of stress, there’s also evidence that it might affect your ability to ward off a cold, too.
Another American study showed some evidence of a link between major stress and colds, Murti said. “People who had more significant stressors seemed to also get more sick compared to people who didn’t.”
Mody said studies have shown that if you expose a group of people to the same stressor — say a group of university students at exam time — their use of medical services around that time goes up, suggesting that they’re feeling sick and visiting the doctor.
But researchers aren’t sure why, exactly.
“What is very complex, and we’ve had a lot of difficulty really nailing it down, is what does that stress do to your immune system that predisposes you to colds and viruses?” Mody asked.
“At a very simplistic level, you could say, the immune system, if it gets busy and misdirected in another way because of the stressful situation, it’s less able to cope with the new type of trigger, like a cold or exposure to a virus, than it might otherwise be.”
But there’s still a lot of research to be done on how exactly the immune system responds to stress, he said. Some people get sick while they’re stressed, and in others, it seems to hit a few days later.
“During the stressful situation, there are body mechanisms being used so that you can perform at that very high level and perform that stressful task,” Mody said. When the adrenaline is pumping, you might not notice if you’re sick. When it wears off and you start to relax, suddenly you feel your sore throat and fatigue.
“It’s not that you didn’t have the infection before. It’s just that you didn’t notice the symptoms from it and now that you’re more relaxed, you feel the symptoms.”
Exposure
Murti is less sure. Colds are caused by viruses that you get from other people, often by touching things that are covered in a virus and then touching your face — bringing that virus into your respiratory system.
If you’re stressed, you might be “hunkered down at your desk” and not socializing as much, she said. “And then when you have a bit of a break afterwards, you may start to go out more and see other people, may have more of an exposure related to that.”
So the best ways to protect yourself, other than trying to relax and get a good night’s sleep, are to do things that limit your exposure: washing your hands frequently, using hand sanitizer as necessary, and not sharing utensils or drinking glasses. And if you’re sick, stay home so that you don’t infect others, she said.