translation.en: You can see this most clearly when you take away someone's watch and you shut them into a bunker, deep underground, for a couple of months.  People actually volunteer for this, and they usually come out kind of raving about their productive time in the hole.
translation.zh: 当你拿走某个人的手表，把他关进一个深入地下的地下堡垒 关上几个月，你就能更清楚地观察到 生物钟的作用。 实际上有志愿者做过这个实验， 他们从洞里出来时 对他们在洞里的时间有点混乱。