Sleep is a natural Nature, in the broadest sense, is equivalent to the natural world, physical world or material world. "Nature" refers to the phenomena of the physical world, and also to life in general. It ranges in scale from the subatomic to the cosmic state of bodily rest observed in humans and other animals. It is distinguished from quiet wakefulness by a decreased ability to react to stimuli, and it is more easily reversible than hibernation Hibernation is a state of inactivity and metabolic depression in animals, characterized by lower body temperature, slower breathing, and lower metabolic rate. Hibernating animals conserve energy, especially during winter when food is short, tapping energy reserves, body fat, at a slow rate. It is the animal's slowed metabolic rate which leads to a or coma In medicine, a coma is a profound state of unconsciousness. A comatose person cannot be awakened, fails to respond normally to pain or light, does not have sleep-wake cycles, and does not take voluntary actions. It is common to all mammals and birds, and is also seen in many reptiles Reptiles, or members of the class Reptilia, are air-breathing, cold-blooded amniotes that have skin covered in scales or scutes as opposed to hair or feathers. They are tetrapods and lay amniote eggs, whose embryos are surrounded by the amnion membrane. Modern reptiles inhabit every continent with the exception of Antarctica, and four living, amphibians Amphibians , such as frogs, toads, salamanders, newts, and caecilians, are ectothermic (or cold-blooded) animals that metamorphose from a juvenile water-breathing form, to an adult air-breathing form. Though amphibians typically have four limbs, the Caecilians are notable for being limbless. Unlike other land animals (amniotes), amphibians lay, and fish A fish is any aquatic vertebrate animal that is typically ectothermic , covered with scales, and equipped with two sets of paired fins and several unpaired fins. Fish are abundant in the sea and in fresh water, with species being known from mountain streams (e.g., char and gudgeon) as well as in the deepest depths of the ocean (e.g., gulpers and. In humans, other mammals, and a substantial majority of other animals that have been studied (such as some species of fish, birds, ants, and fruit flies Drosophilidae is a diverse, cosmopolitan family of flies, including the genus Drosophila, which includes fruit flies. The best known species is Drosophila melanogaster that is used extensively for studies concerning genetics, development, physiology, ecology, behaviour, etc. The fruit fly is mostly composed of post-mitotic cells, has a very short), regular sleep is essential for survival.
The purposes and mechanisms of sleep are only partly clear and are the subject of intense research.[1]
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New York Times
After bouts of activity they skidded to a halt and fell quickly, deeply, luxuriously to sleep . Draped over striped couches, curled on deck chairs, ...
