The Sleeping Habits of Mammals
Reading edition
The tiny elephant shrew (its elongated nose gives it the appearance of a miniature elephant) apparently never closes its eyes. It is a desert animal, continually exposed to danger, and must “see” even when it is asleep.
Soundest sleepers are the burrowing animals, even when they take their naps above ground. They are conditioned through innumerable generations of safe slumber in their subterranean chambers. Sleeping pocket mice and hamsters can be picked up without being awakened.
Sleep habits appear to be well adjusted to the needs of each species. Most bats, for example, sleep hanging head downward, suspended by the nails of the hind feet. This places them in a good position for sudden flight at any alarm. They have only to let go with their toes and spread their wings.
Curious sleepers are the armadillos. They tremble almost continually in their sleep.