SLEEP.

Globe, Volume VI, Issue 611, 3 June 1876, Page 3

SLEEP.

( Times , March 23.) At the London Institution on Monday afternoon Professor Ferrier, of King’s College, delivered a lecture on this subject before a large and deeply interested audience. Dr Ferrier began by remarking that it was quite unnecessary to define what was meant by sleep and dreaming, seeing that the phenomena were so familiar to everyone. Nor did he think it necessary to take up time with an historical account of the speculations respecting the nature of these phenomena, nor of the fancies with which poetical imagination had clothed them. His object was principally to endeavour to reduce the phenomena of sleep and dreaming to the operations of strict natural laws. In order to do so it was necessary first to consider some of the laws and conditions of activity and repose in general. No living being is capable of continuous, uninterraittent activity. All work implies waste, and the possibility of continuous life and activity necessitates as a postulate the constant repair of the waste of action. During active work the process of waste is in excess of the process of repair; hence, if action is kept up, a period comes when the stores of energy are expended. Inaction, rest, or repose follows, during which the waste is again repaired or made good, and the duration of this period of inaction will depend on the rate at which the process of repair proceeds. Illustrations of these genera’ principles were given, the phenomena of the simplest organism, such as the am:cba, were considered, and it was shown that when such organisms were stimulated to constant and prolonged activity, as by heat, they after a time became exhausted and inactive, ami remained quiescent until sullicieut nourishment was again absorbed to repair the waste. What was true of the amaeba was true of the body in general, and its various parts, for the body, in ultimate analysis, in reality consists of elements similar to the auueba, or modifications of these, each with its separate life, but all working together to constitute the general life of the body. The various organs and tissues had, however, their own vitality, and within certain limits were capable of action and inaction independently of that of a body as a whole. The muscles could not be kept in constant contraction. Exhaustion came on, and ultimately refusal to react to any stimulus which might be applied This was well exemplified by the facts ob served whetx the muscle of a frog was stimulated by the electric current applied to the nerve. The contractions became feebler and feebler, and ultimately C Based, the muscle becoming thoroughly ex hausted. During the period of inaction, or sleep of the muscle, the wasted tissues were again restored, the period of rest depending on the degree of exhaustion. What was true of the muscle was true, mutatis mutandis, of the organs of digestion. Some organs seemed to be in a state of constant activity, and therefore might be thought to be exceptions to the general law laid down. This, however, was not bo, for in reality these organs.

the heart and respiratory organs, were not in a state of constant, but of rhythmical activity, a period of action being followed by a pause or rest. The only difference between the heart and the voluntary muscles was that the periods of action and inaction of the heart were short, and followed each other in quick succession. This the lecturer repre seated graphically by curves of action and inaction on the black board. In fact, if the pauses of the heart were all summed up and put together, it would'be found that the heart rested or slept eight hours out of the twentyfour, the sleep being in the proportion of one-third as compared with the hours of action or work The brain, the organ of conscious activity, was kept in constant action during the day for many consecutive hours, and therefore it was necessary that there should be a correspondingly prolonged period of relaxation from action, and repair of the brain waste conditioned by all thought, solution, &c. The rest of the brain was sleep par excellence , but, in addition, sleep was the period during which the repair of the excess of waste over nutrition in the body generally occurred, in so far as it had not been made good during the day. This was proved experimentally by the researches of Fettenkofer and Yoit, who showed that, in reality, more oxygon in the form of carbonic acid, &c. was given off during the day than was taken in, and it was during ■deep that the excess of oxygen was stored np as a reserve fund against the possible needs of the following day. The relation of the duration of sleep to the period of action and its modifying circumstances were also considered and a parallel drawn between the average duration of sleep and the rest of the heart. The physiological condition cf active exertion on the part of any organ is an active circulation through it. The local increase of the circulation, or local hypenemia, was brought about through reflex dilatations of the blood vessels, effected by the organs or tissues themselves. Muscles in a state of action drew a much larger supply of blood than when quiescent; so, also, the stomach during digestion. The same was observed in the brain during active thought. This had been demonstrated by direct experiment, and it was also shown indirectly by the fact that when a large amount of blood was draughted off to any one particular organ, there was an impoverishment of the circulation elsewhere, Hence deep thought, necessitating a large supply of blood on the brain, was unfavorable for digestion. Also, in deep thought, the circulation became feeble in the extremities, hence cold feet, &c. In sleep the brain is anaemic. This has been shown by Durham, Hammond, &c., by way of direct experiment. This is proved, also, indirectly by the greater quantity of blood which circulates in the skin and extremities during sleep. Hence the danger of catching cold during sleep, because there is greater radiation of heat from the skin. Whatever tends to abstract blood from the brain favours sleep. Hence digestion tends to cause sleep, as do hot drinks, &c, by drawing the blood supply from the brain to the stomach. Conversely, whatever tends to keep up the activity of the brain cells and the circulation tends to prevent sleep. This, therefore, is the effect of any st raulus applied to the senses, sights, sounds, thought, anxiety, &c. The opposite favours sleep. Hence night is the period of sleep, because sources of disturbance or stimulation of the organs of sense is diminished or altogether lulled. Uniformity of impression practically is the same as no impression at all. Hence monotony, or uniform rhythm, tends to produce quiescence and predisposition to sleep. The commencement or cessation of the impression is the real stimulus, and therefore a person will awake suddenly when a constant sound is suddenly stopped. Various other practical illustrations were given by the lecturer.