Sleep in animals refers to how the behavioral and physiological state of sleep, mainly characterized by reversible unconsciousness, non-responsiveness to external stimuli, and motor passivity, appears in different categories of animals.
Rats kept from sleeping die within a couple of weeks, but the exact function of sleep is still unknown. Have you had enough sleep this week? Are you looking forward to Friday and then have a really good sleep at weekends? Here we have selected the following 40 Melt-Your-Heart Sleeping Animal Pictures.