SLEEPERS, in natural history, a name given to some animals which are said to sleep all the winter; such as bears, marmots, dormice, bats, hedge hogs, swallows, &c. These do not feed in winter, have no sensible evacuations, breathe little or not at all, and most of the viscera cease from their functions. Some of these creatures seem to be dead, and others to return to a state like that of the fetus before the birth: in this condition they continue, till by length of time maturing the process, or by new heat, the fluids are attenuated, the solids stimulated, and the functions begin where they left off.