床单多长时间洗一次？两星期？一个月？还是半年？ 科学家给出了答案：一星期。 你的肉眼看不见，不代表你的床单不脏。如果床单超过一星期不洗，落在上面的各种细菌和真菌就会让你过敏甚至生病。
纽约大学的微生物学家菲利普•缇艾诺指出，我们有超过三分之一的人生都是在床上度过的，而我们的床可以迅速发展成细菌和真菌的“植物园”。 如果床单太久不洗，床单皱褶里的微生物就会让我们生病 。
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.
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.
为了防范于未然，他表示床单应该每周洗一次。 人类每年在床上自然分泌的汗液达约98升。如果外面炎热潮湿，床上的湿度就会变成科学家所说的“理想的真菌培养基”。
To stem the invisible tide, he said sheets should be washed once a week.
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."
最近的一项研究评估了床上用品的真菌污染水平，研究人员发现，使用年限在1.5年和20年之间的羽绒和化纤枕头含有4到17种不同的真菌。
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.
和你一起睡觉的不光是你身上的微生物。除了你的汗液、唾液、皮肤细胞、私处和肛门分泌物中的真菌和细菌，你还和外来微生物共享你的床。
这些外来微生物包括动物毛屑、花粉、泥土、线头、螨虫尸体和粪便，以及生产你的床单所用的整理剂，这些还只是其中一部分而已。
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.
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.
缇艾诺说，在短短一周的时间里，这些污物就会变得“严重”起来。 不清洁的床单被罩会让你暴露在这些物质中，从而引发鼻炎和喷嚏，因为微生物离你的嘴和鼻子太近了，你几乎是被迫将它们吸进去。 缇艾诺说： “即使你本人不是过敏体质，你也可能产生过敏反应。 ”
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.
"Even if you don't have allergies per se, you can have an allergic response," Tierno said.
双语早读 | 扇子最早不是扇风用的？古人：可以挡脸，可以写小抄
更多精彩请关注：中国日报网微信公众号
