Of course, the common response to today has become, "Don't be silly, being cold can't give you a cold!"

當然現在多數的反應是：「別傻了，天氣冷不會讓你感冒！」

Or can it? Who wins in this battle of the beliefs?

是嗎？這場爭辯中誰才是贏家？

The correlation between cold weather and sickness does stand out.

冷天氣跟生病的關聯是顯而易見的。

Between 5 to 20 percent of Americans catch a cold or flu every year around late fall and winter.

大約 5-20% 的美國人在晚秋和冬天染上流感。

Not to mention, it's called a cold. But there are some important things to consider.

更不用說這個字本身就叫 「著涼」 (感冒)，但還有一些重要因素要考慮。

First and foremost: colds and the flu are caused by viruses. If there aren't any around, you won't catch a cold, no matter how cold you get. It's as simple as that.

首先最重要的：所謂著涼和流感都是病毒引起的，不論天氣變多冷，沒有它們就不會生病，就是這麼簡單。

So why the correlation with decreasing temperatures? Well, for one, people tend to stay indoors much more often during the winter, which in turn, puts them in contact with more people.

那為什麼會跟氣溫下降有關？ 一方面，冬天人們傾向待在室內，因此，使他們和更多人接觸。

More people, means more exposure opportunities for the pathogens to spread.

更多人意味著更多暴露在病原中的機會。

On top of this, humidity plays a role in the spread of some viruses.

除此之外，濕度是一個病毒散播的關鍵因素。

As the humidity decreases in the winter, not only does the virus spread more readily, but the mucus in your nose dries out.

冬天濕度下降，不止病毒更容易傳播，你的鼻腔黏膜也乾了。

Mucus which would otherwise act as a protective barrier to pathogens.

鼻腔黏膜一般扮演抵禦病原的角色。

Finally, the lack of Vitamin D, which we get from the sun, can affect our immune system adversely.

最後，缺乏來自太陽的維生素 D，會使我們的免疫系統下降。

Both being inside more often, and the fact that winter has shorter days makes this a big factor for your health.

在室內時間變長和冬天白晝時間變短都確實會影響你的健康。

So you've proven your parents wrong... right? Not so fast!

所以你證明了你父母是錯的嗎？先別急！

While some past studies have shown no correlation to temperature, recent evidence suggests otherwise.

雖然先前一些研究指出感冒和溫度無關，但最近有證據顯示相反的結果。

One study which put test subjects feet into ice water found that they were, indeed, more likely to develop common cold symptoms in the following days than those who didn't.

有個研究讓受測者把腳放進冰水，結果發現，相對於沒有泡腳的人，他們確實更加容易在接下來幾天產生著涼的症狀。

The developing hypothesis behind these results is that cold temperatures cause blood vessel constriction,

這個研究的發展理論是低溫會使血管收縮，

which slows the white blood cells from reaching the virus, ultimately inhibiting the immune response.

降低白血球找到病毒的速度，最終限制了免疫系統的反應。

Cortisol levels, which suppress the immune system, are also increased with temperature and induce stress.

而會抑制免疫系統的皮質醇，也因溫度增加並產生壓力。

Furthermore, studies on both mice and human airway cells found that immune reaction to the common cold virus is in fact, temperature dependent.

此外，關於老鼠和人類的氣管細胞研究發現，免疫系統對感冒病毒的反應，事實上跟溫度是有關的。

Warm-infected cells are more likely to undergo programmed cell death to limit the spread of infection.

在較高溫度下受感染的細胞會經歷正常細胞死亡流程，以限制感染的散布。

Finally, studies of the virus itself have revealed a secret weapon of sorts.

最後，這些研究揭露了病毒可說是有種祕密武器。

In winter temperatures, the virus' outer layer or envelope becomes much harder and acts like a shield.

在冬天的氣溫下，病毒的外層會變得硬的像是防護罩。

This allows it to spread from person to person much more easily.

這讓它更容易在人群中散布。

But at warm temperatures, this layer is more of a gel, which is not quite tough enough to protect the virus against the elements.

但在溫暖的氣溫下，會變成膠狀的外層，因不夠硬而無法替病毒抵禦外部物質。

As a result, its spreading ability is compromised.

散播能力因此下降了。

So, maybe your parents weren't so wrong after all. A happy compromise of going outside more often, bundled up, is likely to get you through the winter unscathed.

所以你父母也不盡然錯得離譜，所以想要多出門又不會感冒的辦法就是要穿暖一點，這樣能讓你不受冬天病害侵擾。

New to AsapSCIENCE? We've put together a couple playlists to make watching our videos a little easier.

第一次看 AsapSCIENCE？ 我們建了幾個讓你更方便看我們影片的播放清單。

The first is a mix of our favourite and most popular videos, and the other contains every single AsapSCIENCE video in a row... because why not.

第一個清單是我們最喜歡和最受歡迎的影片，其他則包含所有來自 AsapSCIENCE 的影片，因為... 何嘗不可呢?

Also make sure you're following us FB, Twitter, Google plus, Tumblr, Instagram, Vine, and any other social media you can think of.

還有，確定你已經有在 FB、Twitter、Google+、Tumblr、Instagram、Vine 和其他你想得到的社交媒體追蹤我們。

Links in the description.

連結在底下說明中。

As always, ask away any burning questions, and subscribe, for more weekly science video!

像往常一樣，留言任何你極想知道的問題，並訂閱更多每週科學影片！