Sleep

According to this theory, sleep was probably “invented” some two hundred million years ago when sea creatures crawled up on the shore. Land dwellers developed the habit of sleeping as a safety measure. During the day they had to be alert and ready to run away from danger. At night they couldn’t be seen, but they could be heard, so the best thing to do was to stay still and quiet and out of the way. The rest would help them to run faster and farther the next day, and while they were resting they also ensured their inconspicuousness by staying asleep.

Everett B. Mattlin, Sleep less, live more, New York, 1979, p. 67-68

My eyes feel dry and hard as stones…My mind clicks on and off…Sleep is winning. My whole body argues dully that nothing, nothing life can attain is quite so desirable as sleep.

Charles A. Lindbergh, The Spirit of St. Louis, St. Paul, 1953