Emily Dickinson Lexicon

SLEEP, n.

A natural and healthy, but temporary and periodical suspension of the functions of the hemispheres of the cerebrum, or in other words of the intellectual powers. Sleep may be complete or incomplete. That state of an animal in which the voluntary exertion of his mental and corporeal powers is suspended, and he rests unconscious of what passes around him, and not affected by the ordinary impressions of external objects. Sleep is generally attended with a relaxation of the muscles, but the involuntary motions, as respiration and the circulation of the blood, are continued. The mind is often very active in imperfect sleep, but its powers not being under the control of reason, its exercises are very irregular. Sleep is the natural rest or repose intended by the Creator to restore the powers of the body and mind, when exhausted or fatigued. Sleep of plants, a state of plants at night, when their leaves droop or are folded. – Linnæus.