Why does Valet have no eyelids? Why does this bother Garcin?

In Hell.... there is no sleep. There is no use for eyelids if one cannot sleep.

Your eyelids. We move ours up and down. Blinking, we call it. It's like a small black shutter that clicks down and makes a break. Everything goes black; one's eyes are moistened. You can't imagine how restful, refreshing, it is. Four thousand little rests per hour. Four thousand little respites--just think!...So that's the idea. I'm to live without eyelids. Don't act the fool, you know what I mean. No eyelids, no sleep; it follows, doesn't it? I shall never sleep again.