Torpor

Torpor is a physiological state of the body. It occurs in some small warm-blooded animals when food is scarce.
Some animals have periods of torpor every day, including hummingbirds.
So do some small mammals, for example, rodent species (such as mice), and bats. Many small marsupials also have daily periods of torpor.
Torpor is a well controlled thermoregulatory process. It is not the result of switching off thermoregulation.