As it turns out, many blind people people with no visual perception of light at all do have the same sleep cycle as sighted people.

事实证明，许多完全没有视觉感知光的盲人与正常人的睡眠周期是一样的。

Somehow, the eyes of these subjects, even though they were damaged and had no visual perception of light, could tell their brain when there was more or less light.

不知何故，这些受试者的眼睛，即使它们受损并且没有光的视觉感知，也可以告诉他们的大脑什么时候有更多或更少的光线。