Sleep is central to us. It's central to the experience of being human. That every person goes to sleep every night, that we all seek a warm, safe place to cover and restore ourselves for a third of every day, that people of every race and every age do this, that we have done it since before we were
Homo sapiens, is amazing. Lying down to sleep is the most childlike of gestures, the most trusting. It is at the same time a symbol of ebbing life force, a rehearsal for the day we will lie down and not get up.
- D.T. Max, The Family That Couldn't Sleep
