你的床單多長時間洗一次呢？兩星期？一個月？還是半年？科學家給出了答案：一星期。你的肉眼看不見，不代表你的床單不臟。如果床單超過一星期不洗，落在上面的各種細菌和真菌就會讓你過敏甚至生病。

截圖來自ScienceAlert網站

We spend more than a third of our lives in bed - but that place can quickly blossom into a "botanical park" of bacteria and fungus, according to New York University microbiologist Philip Tierno.
紐約大學的微生物學家菲利普?緹艾諾指出，我們有超過三分之一的人生都是在床上度過的，而我們的床可以迅速發展成細菌和真菌的“植物園”。

If left for too long, the microscopic life within the wrinkles and folds of our bed sheets can even make us sick, Tierno told Business Insider.
緹艾諾告訴商業內幕網說，如果床單太久不洗，床單皺褶里的微生物就會讓我們生病。

To stem the invisible tide, he said sheets should be washed once a week.
為了防范于未然，他表示床單應該每周洗一次。

Humans naturally produce roughly 26 gallons of sweat in bed every year. When it's hot and humid outside, this moisture becomes what scientists call an "ideal fungal culture medium."
人類每年在床上自然分泌的汗液達26加侖。如果外面炎熱潮濕，床上的濕度就會變成科學家所說的“理想的真菌培養基”。

In a recent study that assessed the level of fungal contamination in bedding, researchers found that feather and synthetic pillows between 1.5 and 20 years old can contain between four and 17 different species of fungus.
最近的一項研究評估了床上用品的真菌污染水平，研究人員發現，使用年限在1.5年和20年之間的羽絨和化纖枕頭含有4到17種不同的真菌。

And it's not just your own microbial life you're sleeping with. In addition to the fungi and bacteria that come from your sweat, sputum, skin cells, and vaginal and anal excretions, you also share your bed with foreign microbes.
和你一起睡覺的不光是你身上的微生物。除了你的汗液、唾液、皮膚細胞、私處和肛門分泌物中的真菌和細菌，你還和外來微生物共享你的床。

These include animal dander, pollen, soil, lint, dust mite debris and faeces, and finishing agents from whatever your sheets are made from, to name a few.
這些外來微生物包括動物毛屑、花粉、泥土、線頭、螨蟲尸體和糞便，以及生產你的床單所用的整理劑，這些還只是其中一部分而已。

Tierno says all that gunk becomes "significant" in as little as a week. And unclean bedding still exposes you to materials that can trigger the sniffing and sneezing, since the microbes are so close to your mouth and nose that you're almost forced to breathe them in.
緹艾諾說，在短短一周的時間里，這些污物就會變得“嚴重”起來。不清潔的床單被罩會讓你暴露在這些物質中，從而引發鼻炎和噴嚏，因為微生物離你的嘴和鼻子太近了，你幾乎是被迫將它們吸進去。

"Even if you don't have allergies per se, you can have an allergic response," Tierno said.
緹艾諾說：“即使你本人不是過敏體質，你也可能產生過敏反應。”

截圖來自商業內幕網

Another reason your sheets get dirty quickly has little to do with your behaviour or sweat patterns - the issue is simply gravity.
你的床單迅速變臟的另一個原因和你的行為或流汗模式沒有太大關系，問題主要在于重力。

"Just like Rome overtime was buried with the debris that falls from gravity, gravity is what brings all that material into your mattress," Tierno said.
緹艾諾說：“就像羅馬隨著時間的流逝最終會被重力拉垮，被碎片掩埋，重力也將所有這些物質帶到了你的床上?！?/p>

One to two weeks of this build-up is enough to leave anyone with a scratchy throat - especially those with significant allergies or asthma.
這些物質在床上累積一到兩周就足以讓任何人喉嚨發癢，尤其是那些有嚴重過敏或哮喘病史的人。

"If you touched dog poo in the street, you'd want to wash your hands," said Tierno. "Consider that analogous to your bedding. If you saw what was there - but of course you don't see it - after a while you have to say to yourself, 'Do I want to sleep in that?'"
緹艾諾說：“如果你在街上碰了狗屎，你會想洗手。如果你的床單上粘上了不干凈的東西呢？如果你看到了床單上的那些物質——當然你看不到——你得問問自己：‘我想睡在那張床上嗎？’”

英文來源：商業內幕網
翻譯&編輯：丹妮