Articles, Blog

Why Do We Get Colds When It’s Cold?

November 8, 2019


At some point during your childhood, you were
probably told not to go out in cold weather with wet hair, or without bundling up, because
“you’ll catch a cold.” But we know the common cold is caused by
viruses, not chilly air. So why does this old wives’ tale hang around? It’s probably because colds are more common
in colder weather. But as far as scientists can tell, that’s
not because you feel cold. There are lots of better explanations for
why colder weather increases your odds of getting sick. The connection between temperature and illness
isn’t simple. Even though colds and other respiratory illnesses
are more common in colder months, not all of them spike in the dead of winter, when
it’s coldest. And the most direct studies we’ve done haven’t
found a relationship between feeling cold and catching a cold. For example, in a randomized controlled trial
published in 1958, researchers divided nearly 400 people into rooms that were either 27
degrees, 16 degrees, or -12 degrees Celsius. Then they put virus-infected mucus up some
of their nostrils. But the temperature didn’t make a difference
— in every room, just over a third of the volunteers that received the infected mucus
got sick. One study from 2005 did find that people who
had their feet soaked in freezing cold water reported more cold symptoms in the days afterward
compared to a control group. But it’s hard to tell how much of that was
influenced by subjects thinking they’d be more likely to get a cold. If feeling cold really does make you more
likely to get sick, there are a couple of ideas that might explain it. One hypothesis argues that even though the
cold doesn’t weaken your immune system overall, it might lower the defenses in your respiratory
system, specifically. And in a paper published in 2016 in the journal
Medical Hypotheses, a microbiologist suggested that viruses lie dormant for extended periods
of time in our bodies, then get activated when the temperature drops. But there are lots of problems with those
ideas. And the vast majority of
research shows that simply being cold doesn’t make you more vulnerable to catching colds. Instead, there are other aspects of cold weather
that might increase your chances of getting sick. Like the fact that the air is super dry. Colder weather is associated with lower humidity,
because at lower temperatures, the air can’t hold as much water. When humidity is high, the droplets of virus-infected
grossness we breathe out or sneeze out or cough out of our bodies stay large and drop
to the floor relatively quickly. But in dry air, they break up into smaller
particles and can float around for hours. Plus, the lack of moisture can dry out the
mucus lining in your nose, which might make it easier for viruses to get past that line
of defense. Another potential problem is that some people
don’t get enough sunlight in the winter, making them run low on vitamin D. Since vitamin
D helps power your immune system, lower levels mean lower defenses against viruses. And then there’s the fact that human behavior
changes during colder months. We’re more likely to stay indoors, which
means we’re more frequently touching stuff infected people touched, and breathing in
the remnants of their sneezes. [deep breath] Mmmm… So, researchers are still trying to pin down
all the different ways cold weather may or may not affect how likely you are to catch
a cold. But the best way to avoid catching one isn’t
necessarily by throwing on another layer, or drying your hair before running out the
door. It’s washing your hands with soap, not touching
your face with unwashed hands, and staying away from people you know are infected. Thanks for watching this episode of SciShow! And a special thanks to our patrons on Patreon,
who help us keep the heat running all winter, and contribute by asking questions like this
one. To submit your own questions, you can head
over to patreon.com/scishow. ♪ OUTRO ♪♪

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35 Comments

  • Reply Wade Haden January 1, 2018 at 8:39 pm

    It's not just viruses….dumbass! I CAN RELATE TO THE VITAMIN D THING, BUT HAS SCIENCE NOT CONSIDERED OTHER "ENERGETIC" CHANGES BESIDES LESS LIGHT?

  • Reply Rohen Giralt January 2, 2018 at 11:28 am

    First part of video: Donโ€™t go outside. Stay indoors where itโ€™s humid
    Me:Got it
    Second part of video: Go outside. Inside is dangerous
    What do you want me to do, SciShow? Live in the door?

  • Reply C Levi January 2, 2018 at 8:50 pm

    In some parts of the world people also travel more during winter or are in malls more which means you're around more people, increasing your likelihood of getting a cold.

  • Reply Talsen 64 January 3, 2018 at 1:04 pm

    huh. I always thought it was simply because of the temperature of the cold air that is being breathed in mixing with the warmth of the body makes the temperature perfect for infections to grow.

  • Reply Sci-Wise January 4, 2018 at 7:46 pm

    Like it. There are similar videos with cool illustrations here:
    Link: youtube.com/c/sciwise

  • Reply flaming Turnip January 7, 2018 at 8:14 am

    I think the connection to drying out nose and throat lining makes sense. When I bike to class during the winter and breathe in cold air I almost ALWAYS get sick (whether that's viral, allergy related, or otherwise I can't say, but its always the same symptoms. Headache, congestion, fatigue)

  • Reply Gene Sky January 7, 2018 at 11:05 am

    Some viruses live and grow better at cold temperatures.

    All life has optimum living temperature , cold , to , hot.

  • Reply Snakeyes244 January 16, 2018 at 5:25 pm

    HELL YEAH! This is real myth-busting!

  • Reply CB Droege January 22, 2018 at 11:12 am

    With the sunlight and cabinfever associations, it actually sounds like it's staying in, not going out in the cold, that make us sick. So, we need to reverse all our winter advice, and take more walks in the snow.

  • Reply Bill Wells January 25, 2018 at 5:06 am

    https://www.amazon.com/No-More-Colds-Search-Cure/dp/1534941738

  • Reply Bill Wells January 25, 2018 at 5:08 am

    No more colds. It's the nose silly. The Nose incubates colds. https://www.amazon.com/No-More-Colds-Search-Cure/dp/1534941738

  • Reply Angeles Carr January 30, 2018 at 4:29 pm

    I always thought it was because the cold weather interrupted the homeostasis of the body and we got sick since hot weather kills bacteria but cold preserves it. ๐Ÿ˜ฑ

  • Reply Morgan Bennett February 1, 2018 at 5:17 am

    I hate that

  • Reply R & h Kaur February 4, 2018 at 10:48 am

    So i canโ€™t touch my face now WOW !!!๐Ÿ˜ซ๐Ÿ˜ฉ๐Ÿ˜‚๐Ÿคข

  • Reply ihartevil February 9, 2018 at 1:03 am

    actually our immune systems are higher in the winter so some people like me are just allergic to the cold air and that never gets looked into for the rest they were probably stupid got the flu shot weakening their immune system so they became more likely to get sick and die

    thx for this ha bisky vid the only people i know whoever got sick in the winter were the morons that got the flu shot

  • Reply hit circle March 2, 2018 at 7:34 am

    Anyone watching this with a cold ?

  • Reply Simply Sookie April 25, 2018 at 10:04 pm

    You are a very attractive man. Yes you are.

    ๐Ÿ™‚

  • Reply JorgeForge September 20, 2018 at 1:27 am

    I got the impression that when our body is loosing heat, due to cold weather, it tries to warm itself up switching resources from defending against infections to maintaining constant body temperature. It just can't do both things as efficiently. This opens a path for viruses / bacteria to infect us.

    So, even though the temperatures outside is below 0C, which kills the things causing "cold/flu", once you loose body heat and walk into a warm cosy home, you're like an open door, inviting all the nice, sickness causing organisms to infect you.

  • Reply Christopher Deveau October 1, 2018 at 6:06 pm

    where is hank

  • Reply Another Idiot October 11, 2018 at 12:34 am

    Well, I live in Canada and I sleep with my window open.

  • Reply Shane Stephen October 16, 2018 at 11:41 pm

    Tell that to government sheep. People get sick in the cold months period. Flu in the winter thats why they advertise flu shot in cold months

  • Reply I B October 20, 2018 at 4:20 am

    Okay that experiment was just gross

  • Reply ramrod 60th November 20, 2018 at 4:17 pm

    The reason we have cold season is because the people with poor immunity get sick and then come around everybody else that isn't that have a good evening unity and sneeze all over them and touch everything people are disease they should stay

  • Reply Kaylie Henderson December 8, 2018 at 10:08 am

    Plot twist: he got a cold after recording this video

  • Reply Edu Orta December 26, 2018 at 11:39 pm

    So, can I say "I told you" to my parents now?

  • Reply Jeffrey Rivers January 11, 2019 at 5:14 pm

    Do you have a hat on?

  • Reply Ahmed Qusay January 23, 2019 at 12:44 pm

    If its cold and wear too much clothes and sweat that's a guaranty to catch common cold why???

  • Reply TwinShards March 23, 2019 at 12:00 am

    And me that almost never wash my hand, doesn't avoid at all any risk of getting sick. And i never get sick.
    Well. I'm pretty sure if you keep your Immune system very active (which mean to not clean your hand every single time) you can survive much better against infection from all around.

  • Reply Aykut Nurat March 23, 2019 at 6:03 pm

    This video is quite faulty indeed. There is a serious research about flu affects and cold weather relationship: https://www.pnas.org/content/112/3/827#sec-1

    very very briefly, flu is related to viruses that's correct but it looks like that cold weather affects immune system and it affects how you deal with the flu.

  • Reply philip kou June 15, 2019 at 1:36 pm

    Itโ€™s definitely the cold weather , welcome to Canada where the Tylenol companies are making a killing

  • Reply ukidding August 18, 2019 at 7:42 pm

    i finish with a cold shower,,,in the hope that it strenghtens the immune system

  • Reply Sahil Tanwar September 29, 2019 at 8:55 pm

    I hav cough cold after i sleep under fan during winter coming days
    I dnt knw it virus or ….. bla bla
    I fked up . I hav breathing prob , runny nose

  • Reply Milli Barnard October 1, 2019 at 9:55 am

    I have a cold

  • Reply Alex Harris October 8, 2019 at 1:42 am

    Just got a cold from sleeping with ac on…

  • Reply Hystel Studios October 27, 2019 at 9:03 am

    Me: *starts video and i put my unwashed hand on the face*
    Also me: *sees 2:54*
    Again me: *immediately puts hand on the table*

  • Reply Priyankar Malla October 30, 2019 at 5:55 am

    Too good a video .. A question that was on my mind for years.. finally got my answer

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