Who Sleeps?
Reptiles, birds and mammals all sleep. Some fish and amphibians reduce their awareness but do not ever become unconscious like the higher vertebrates do.
Insects do not appear to sleep, although they may become inactive in daylight or darkness.
By studying brainwaves, it is known that reptiles do not dream. Birds dream a little. Mammals all dream during sleep. Whales and dolphins are “conscious breathers” and because they need to keep conscious while they sleep in order to breathe, only one half of their brain sleeps at a time.
GLOSSARY:
awareness = consciência
In “... although they may become inactive...”, the underlined word implies an idea of
