Domestic Encyclopædia (1802)/Sleep, in Physiology

2440175Domestic Encyclopædia (1802), Volume 4 — Sleep, in Physiology

SLEEP, is that condition of the body, in which the senses are not excited or affected by external objects; while the functions of life are regularly performed, though not with the same energy or celerity, as is observable in a waking state.

"Tir'd Nature's sweet restorer, balmy sleep," is one of those requisites, which are indispensable to the continuance of life and health: thus, providential Nature has appropriated the night for the recovery of that strength, which had been expended by exhausting the irritable principle during the day.

The disposition to sleep is indicated by a drowsiness pervading the whole system: the senses and muscles become languid; the head, unable to retain its erect position, bends towards the chest; the eye-lids close; and, at length, the ideas become confused; and the intellectual faculties are suspended.

Sleep not only contributes to reinvigorate the muscular power, but also promotes nutrition; because the organs of digestion act, on the whole, more speedily and effectually in this state of rest, than during bodily exercise. Hence, many persons are accustomed to take a nap, regularly after dinner; a practice which has, by some, been highly commended, for its invigorating the body, and enabling it to undergo additional fatigue; while others have censured it, as tending to induce corpulency, a phlegmatic or phlethoric habit, and various indispositions.—The relative propriety of this indulgence, however, depends on particular circumstances. Thus, if a person eat solid or hard food, or be naturally of slow digestion, a short sleep (not exceeding one hour, at the farthest) may be of service; but, in cases of debility, and great muscular relaxation, such practice ought by no means to be encouraged, particularly by the young; as each repetition will have an aggravating effect.

In taking this nccessary repose, the body ought to be reclined on the left side, in a straight direction, with the limbs slightly bent; the head being rather elevated. The body ought, on no account, to be placed in a crooked posture; as it impedes the circulation of the blood, and pre-disposes the system to swoonings, or apoplectic fits. Lying on the back is equally improper; as it tends to produce frightful dreams, and numerous inconveniencies, especially the night-mare.