It’s eleven o’clock Sunday morning, and you’ve just woken up after a late night of carousing. You stumble out of bed, brace yourself on the bathroom sink and blink into the mirror.

There, under your eyes, are dark, puffy patches that make you look like an NFL linebacker. I need more sleep, you think, fingering the dark spots. And so you stumble back to bed.

Do I Need More Sleep?

You may indeed need to sleep a bit longer, but despite the common misconception, dark circles and puffiness under or around your eyes appear to have little to do with lack of sleep.

In fact, what seems to be a fairly common and hence supposedly explainable phenomenon remains something of a mystery to scientists.

Mystery

What scientists do know is that the skin under the eyes is very thin and sensitive. When for a variety of reasons blood and other fluids accumulate in the area under your eyes, the delicacy of the skin makes the fluid’s color partly visible. This is what appears to account for the dark patches.

Allergies may also be to blame. An allergic reaction can cause cells under the skin of the eyes to release histamine, a chemical that causes fluid accumulation and swelling. This is what appears to cause puffy eyes.

And finally, there is heredity. Do your parents have dark circles under their eyes? If so, you may have found the source for your own dark circles.

为何会形成黑眼圈?

现在是周日上午11点，而你刚从前一晚的狂欢过后醒来。你跌跌撞撞地走下床，双手撑在盥洗台上，睡眼惺忪地看向镜子。

看到了吗，你眼睛下面那深色浮肿的眼袋，让你看起来像美国橄榄球联盟的后卫队员。用手抚摸着黑眼袋，你想，我需要更多的睡眠。于是你又踉跄着回到床上。

我需要更多睡眠吗?

也许你的确需要多睡一会儿，尽管有着普遍的误解，但眼周或眼底的黑眼圈和浮肿似乎与睡眠不足没有太大的关系。

事实上，这个看起来相当容易解释的常见现象对科学家们来说却仍然是个谜。

谜题

科学家们所知道的是，眼底的皮肤非常薄，非常敏感。当由于种种原因，血液和其他液体在眼底部位积聚时，这层细腻的皮肤就会使得液体的颜色浮现出来。这似乎才是黑眼圈形成的原因。

过敏也是可能的原因之一。过敏反应导致眼底皮肤细胞释放出组胺，这种化学物质会引起积液和皮肤肿胀。这似乎才是眼袋形成的原因。

最后还有遗传因素的影响。你的父母是否有黑眼圈?如果有，也许你就能够找到你有黑眼圈的原因。