Why Grandma was right when she said “Wear a hat outside in the cold so you won’t get sick.”

As a pediatrician, I used to scoff at the “wives’ tale” that grandmothers told their children and grandchildren when they went outside. “Wear a hat so you don’t get sick!” they would exhort us. When my patients asked why their kids got sick more frequently during the winter, I told them what I had learned. The reason that upper respiratory tract infections rise during the winter months was probably due to the fact that people spend more time indoors in closer contact with others.

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A new study released by Harvard Medical School shows us doctors that we were wrong and that, surprise, grandmothers were right all along.

Cold air does, in fact, affect the number of head colds we get in the winter. Until their study, no one really understood the body’s immune response in the nose to typical upper respiratory infection viruses.

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According to The new study, published Dec. 6 in the Journal of Allergy and Clinical Immunology, when a virus enters the nose (either through the air or by touch) it lands in the front of the nose. The nose alerts the cells nearby that a virus has hit. Then, the cells produce millions of small vesicles called extracellular vesicles or EV’s. These EV’s swarm to the front of the nose, attacking the viruses. They also grab bacteria fighting proteins and shuttle them to the back of the nose to protect those cells. This keeps the virus from going farther in the nose and moving into the bloodstream.

But the EV’s do more. They have the ability to “grab” hold of the viruses themselves and dump them into nasal mucus, in a sense deflecting them from going to the back of the nose. The whole process is extraordinary when you think about it.

Here’s where cold air comes in. During the winter, when the temperature drops, the temperature inside the nose drops too. The study shows that when they are cold, the cells inside the nose are unable to release as many EV’s by a whopping 42%. With fewer EV’s, the nasal cells aren’t able to fight off the viruses and bacteria as effectively.  Also (not to get too technical) but the proteins in the EV’s are less effective in the cold. So, the immune system inside the nose takes a double hit.

And that’s where Grandma comes in (I love this part because I am a grandmother and now-perhaps-my own kids will listen to me.) She knew that cold temperatures lead to head colds that also lead to ear infections. “Put on a hat and keep your ears covered!” she would say. Would kids listen? Usually not.

Does the cold air itself produce ear infections? No, but having colds leads to them. When a child develops a head cold, the cells produce more fluid - in the nose, throat, sinuses and Eustachian tubes (the canal going from behind the eardrum to the back of the throat.) Most of the time, the fluid drains from the head, but when children are young, their Eustachian tubes are narrow, thus making it hard for any fluid that collects behind the eardrum to drain. When this fluid stays there at normal body temperature (98.6 degrees) the bacteria move in and take over. Thus, the ear infection.

When a child develops an ear infection, he often doesn’t let you know his ear hurts until he lies down. This is because the infected fluid behind the ear drum doesn’t put pressure on the eardrum until he is flat. So, when he goes to bed at night, the infected fluid pushes against the inflamed eardrum and this hurts. That’s why kids wake up screaming at night with an ear infection. They genuinely felt fine until they laid down.

As one who has suffered from a lot of ear infections (one of the job hazards) I can tell you that they hurt! Back in the old days, I could spot a child with an ear infection coming through the emergency room doors at 3:00 am. The child’s face would be beet red, he would be screaming and holding his ear. He wasn’t being histrionic. He felt like his ear would explode. It was because of this level of pain that we would sometimes give kids a whiff of codeine to help the pain until the antibiotic kicked in - usually 24 hours later.

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So, what are parents supposed to do with this information? Here are some tips.

1. When it’s cold outside, listen to your mother. Make your child wear a hat and neck warmer if it’s really cold. This won’t completely keep your child’s nose from getting colder but it will help by keeping the head at a warmer temperature.
2. If you have small children who are more likely to get ear infections, try putting them outside for more frequent, shorter periods of time. This may keep the nose temperature from dropping as much.
3. After your child has been out in the cold for a long time, be extra diligent about having her wash her hands. When the nose temperature drops, then the viruses move in. Some are inhaled and you can’t do much about that but you can decrease the number that enter through the nose via hands and fingers.
4. Get out the hot chocolate (or warm milk.) When kids come in from the cold, giving them a hot drink can allow them to inhale steam through their nose. There is no scientific evidence that this will keep them from getting a cold but it will help the nose temperature rise. And - well - it feels like a good mother - intuition - thing to do. 
5. Don’t get paranoid. Sometimes we, who worry, go overboard when we hear information like this and we over react by keeping our kids from doing things. Don’t. There are far more advantages for kids to be outside playing in the winter, risking a cold, than there are disadvantages. Kids need to burn off energy. They need fresh air. Mentally, getting outside and running, sledding or building a snowman leads to a much happier child - yes - perhaps with more upper respiratory infections or maybe even an ear infection. But - at least you’ll know that mentally, he’ll be far happier.

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