如果你覺得最近頭髮掉的厲害,那可能是這個原因大綱

If you've been staring at your brush or your shower drain and feeling like you've been losing a lot of hair lately, don't freak out. A new British Journal of Dermatology study suggests that shedding more strands in the summer and fall is totally normal.

如果最近你老是盯着梳子或浴室排水閥，感覺自己掉了很多頭髮，千萬不要驚慌。英國《皮膚病學雜誌》刊出的一項新研究表明：夏天和秋天頭髮掉的比較厲害是完全正常的。

A seasonal pattern of hair loss has been long suspected; it's been observed anecdotally and documented in previous small studies. But those studies have focused on just one geographic location, so it hasn't been possible to know if those findings apply to everyone.

長久以來，人們一直懷疑掉髮有季節規律。先前的小型研究已經觀察到了這種現象。但這些研究只在某一區域進行，所以並不清楚是否對所有人適用。

Researchers at Johns Hopkins and Washington University changed that by compiling Google Trends data from eight countries in four hemispheres with high search rates for the term "hair loss." They looked at search volume from 2004 through 2016, and compared the data month to month and season to season.

約翰霍普金斯大學和華盛頓大學的研究人員通過編譯來自四個半球八個國家的谷歌數據改變了這一情況，這些國家搜索"掉髮"一詞的頻率很高。他們查看了從2004年到2016年的搜索量，並將這些數據按月份和季度進行比較。

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Across all eight countries, the results were the same: People searched the Internet using phrases related to hair loss more frequently in the summer and fall compared to the winter and spring. The finding is relevant to doctors whose patients complain of hair loss in those two seasons, the authors say, and it may be useful in assessing how effective certain therapies are at treating the condition. But more research is needed, they add, to determine exactly why this pattern happens-and how much patients should care.

八個國家的結果都是一樣的：與春冬兩季相比，人們更頻繁地在夏秋兩季搜索與掉髮相關的信息。研究作者表示，這一結果也與某些醫生息息相關，這些醫生的病人會在夏秋兩季抱怨自己掉髮；這一結果可能有助於評估治療掉髮的方法的有效性。他們補充道，還需要更多的研究來確定爲什麼會發生這一季節性規律--以及病人需不需要注意這個問題。

"Mildly increased hair loss in the summer and fall is normal," co-author Shawn Kwatra, MD, assistant professor of dermatology at Johns Hopkins University School of Medicine, tells Health. "This is speculative, but from an evolutionary perspective one of the roles of hair loss is to provide warmth," he says. "This would be less necessary during the summer months."

"夏秋兩季有輕度掉髮是很正常的，"合著作者Shawn Kwatra醫學博士對《健康》雜誌表示，他還是約翰霍普金斯醫學院的皮膚病學助理教授。"這是推測性的，但從進化的角度來看，掉髮的一個作用就是供暖，"他說道。"而夏季並不需要供暖。"

The tendency to grow thicker coats in the winter-and shed them in the summer-has also been documented in a variety of animals, including monkeys, cats, dogs, and camels. In humans, seasonal hair loss has been reported more in women than in men, Dr. Kwatra says, although the current study could not distinguish Google searches by gender. According to the American Academy of Dermatologists, it's normal to lose between 50 and 100 hairs a day.

冬季留長髮，夏季剪短髮的趨勢在動物身上也很常見，包括猴子、貓咪、狗狗和駱駝。女性季節性掉髮的情況比男性更多，Kwatra醫生說道，雖然現在的研究並不能判別搜索谷歌的人的性別。據美國皮膚病學會資料表示，每天掉50至100根頭髮是很正常的。