你会发光，只是没人看得见

即使坐在一间完全黑暗的房间里，你依然在发光。你的皮肤会持续散发出微弱的光芒，而这与体温毫无关系。

Sit in a completely dark room and you are still giving off light. Your skin emits a faint glow, continuously, and it has nothing to do with body heat.

一支日本研究团队在二零零九年证实了这一点。他们让志愿者赤裸上身进入一间完全不透光的房间，用一台极其灵敏的相机对着他们拍摄二十分钟。相机捕捉到皮肤上持续而斑驳的光芒，脸部区域最亮。这种光其实是细胞内部普通化学反应的副产物：涉及氧气的反应在进行时，会不断释放出单个的光粒子。

A Japanese team proved it in two thousand and nine. They put volunteers, stripped to the waist, into a light-tight room and pointed an extremely sensitive camera at them for twenty minutes at a time. The camera picked up a steady, patchy shine coming off the skin, brightest around the face. The glow is a by-product of ordinary chemistry inside your cells: reactions involving oxygen throw off single particles of light as they go.

不过这里有个关键点，也解释了为什么从来没人注意到这件事：这种光大约比人眼能察觉的最微弱光线还要暗一千倍。你永远看不到它，别人也一样。同一项研究还发现，这种光会在一天之中起伏变化，早晨最弱，傍晚最强，这说明在这一切背后，你的脸其实在按照某种规律运作。

There is a catch, and it explains why nobody ever noticed. The light is roughly a thousand times weaker than the faintest thing a human eye can detect. You are never going to see it, and neither is anybody else. The same study found the glow rises and falls across the day, weakest in the morning and strongest in the late afternoon, which means that somewhere in all of this your face is keeping a schedule.