SLEEP. - From a biological point of view, sleep reveals itself as an aspect of a phenomenon common to all living beings, in the animal and plant kingdoms, which have alternations of activity and rest. Houssay defines it as a necessary physiological state, restorative, normally periodic and reversible, characterized by a depression of sensitivity, of consciousness and of spontaneous motility and above all of muscular tone, without there being a notable lowering of the basal metabolism and without a perceptible slowing of the vegetative functions.
I. PHYSIO-PATHOLOGY OF SLEEP
The passage from the waking state to that of sleep is normally progressive and is heralded by a sense of fatigue, of heaviness, of letting go, by a lack of interest in what happens around us, by difficulty in keeping the eyes open; it comes on after an alternation of phases of attention and inattention during which hypnagogic hallucinations take place, represented by disconnected, momentary images that undergo rapid metamorphoses and vanish upon opening or moving the eyes.
In sleep, relaxation of the entire musculature predominates, except that of the masseters, of the orbicularis of the eyelids, of the sphincters and of the fist in the child. The pupils are contracted and the eyeballs are rotated upward and outward. The number of heartbeats decreases by 10-30 per minute and the arterial pressure by 10-20 millimeters of mercury. The number of respiratory excursions also decreases, with a long and noisy inspiratory phase and a rapid expiratory phase. The basal metabolism falls, in deep sleep, by 10-15% and the body temperature drops by a few tenths of a degree. Sweat secretion increases in deep sleep and the urine is less abundant, but dense, acid and richer in phosphates. Gastric function undergoes no notable variations. Cerebral activity is diminished but not abolished. In the electroencephalogram, in deep sleep, all the rapid waves disappear and only the very slow waves persist. The average duration of physiological sleep varies according to age, constitution, occupations, season; in general the newborn sleeps 20 hours a day and a child from one to seven years old sleeps from 10 to 14 hours; the adult sleeps from 7 to 9 hours and the old person from 5 to 6 hours. Sleep is an indispensable need of the organism. Some experimenters, among them Kleitman, have observed that after 80-115 hours of insomnia the persons they studied presented modest psychic disturbances; it has nevertheless been found that a prolonged insomnia of ten days produces death in man, if sufferings of another kind coexist. Sleep is favored by all those causes that reduce sensory excitations, that is, darkness, silence, the lying-down position, fatigue; conversely it can be hindered by movements, by discontinuous noises, by emotions, by physical pain, by worries, etc.
Among the disorders of sleep the following are recalled: 1. Simple constitutional hypersomnia: it is characterized by a particular tendency to fall asleep even during the day in the face of even partially favorable conditions such as heat, silence, boredom. 2. True hypersomnia: it consists in a marked disposition to fall deeply asleep even when environmental conditions are not suitable. 3. Narcolepsy: a paroxysmal crisis of sleep whereby the patient feels an invincible drowsiness: his eyelids close, he falls asleep and this sleep lasts from a quarter of an hour to one and even two hours; he then wakes up refreshed and ready to resume his occupations. There may be one or several crises a day. The attacks begin suddenly and rapidly, but not brutally, so that the patient often has time to choose the place where he will sleep. It may be associated with cataplexy: the patient falls to the ground for a few moments, but his fall is not as abrupt as in the apoplectic act or in the epileptic attack; he witnesses his crisis in full consciousness but cannot utter a word. This crisis lasts a few seconds or a few minutes, and even half an hour; then the patient gets up again and immediately resumes the interrupted occupations. The association of narcolepsy with cataplexy constitutes Gélineau's syndrome; both the former and the latter are related to emotional events. 4. Lethargic encephalitis: it is caused by a filterable virus that is believed to be endowed with a marked nervous affinity and especially for the gray matter of the third ventricle. It manifests itself with a more or less marked drowsiness and with phenomena of deficit of the cranial nerves, especially of those that innervate the external musculature of the eye. 5. Sleeping sickness or African trypanosomiasis: it is caused by trypanosoma gambiense transmitted by glossina palpalis and by trypanosoma rhodense transmitted by glossina morsitans, flies of the tsetse type. It is characterized by fever, enlargement of some glands, drowsiness and then prolonged sleep and terminal coma. 6. Hypnotism (v.): it is a sleep artificially provoked by means of suggestion. 7. Insomnia: it consists in the difficulty of falling asleep or in the difficulty of resuming sleep after having woken up. Insomnia of the first period is found in erethistic subjects, in persons who digest badly, in many children who have dreams that impress them; sometimes it depends on the decubitus of the patient, as in cardiac patients who wake up easily when they are supine. Insomnia of the second period is found in chronic intoxications from alcohol, in the abuse of coffee, in bad digestions, in sexual excesses, in painful affections, after tiring work, in anxious states.
Among the substances capable of inducing sleep, mention should be made of the opiates and barbiturates that are administered by mouth or by injection; ether, chloroform, nitrous oxide and ethyl chloride that are used by inhalation. Other substances such as simpanina, pervitin, etc., serve to combat drowsiness.
II. VARIOUS THEORIES OF INTERPRETATION OF THE GENESIS OF SLEEP
Numerous theories attempt to explain the genesis of sleep. Blumenthal in 1875 adduced that sleep is due to cerebral ischemia, but Czerny in 1891 and Brodmann in 1902 demonstrated that in sleep there is instead dilation of the cerebral vessels. W. Preyer in 1875 maintained that sleep is produced by the accumulation in the organism of hypnogenic substances that are produced by fatigue. Two facts stand against this theory: first, there is no correspondence between the degree of fatigue and the depth of sleep; second, the sleep produced by monotonous noises, by darkness and by silence remains unexplained. Lépine in 1895 attributed sleep to the retraction of the cerebral ramifications of the central sensory neuron, similar to that of pseudopodia; upon waking these ramifications would lengthen; however, Ramon y Cajal and others have denied the existence of these amoeboid movements. Claparède in 1905 put forward the psychological theory of sleep: primitive man defended himself with sleep from the discomforts of the night, whence the need to sleep at night, hereditarily transmitted by his ancestors. Sleep would be a reaction of disinterest. Piéron in 1913, after having found that the injection of cerebrospinal fluid from a dog in a state of insomnia into an awakened dog provokes in the latter a deep sleep, held that this is caused by a hypnotoxin produced by the brain in the waking state. It has, however, been demonstrated that analogous effects are produced by injections of normal cerebrospinal fluid. Zondek and Bier advanced the hypothesis that the pituitary gland produces a brominated hormone with hypnotic action. Pavlov in 1927 put forward a theory according to which sleep would be the effect of a process of irradiated internal inhibition. But the theory is at least incomplete, because it does not explain, for example, the sleep of newborns, who sleep before they have acquired conditioned reflexes. Kleitman in 1929 explained sleep by the reduction of the afferent stimuli that continuously reach the cortex and more especially of the proprioceptive excitations that originate from the muscles under the influence of muscular tone. This diminution of excitations, due to fatigue or to muscular relaxation, would be the most important factor in the onset of sleep.
In all the above-mentioned theories, account has been taken above all of the cortical substrate of the brain. It is a fact, however, that observers who have carried out studies on animals, especially dogs and cats, have noted that, following decortication, states of drowsiness appear equally in them, at least in appearance, not unlike those observed in normal animals. The only effect produced by decortication, observes Spadolini, is that of converting the periodicity of sleep and wakefulness from a monophasic diurnal type (long sleep during the night and brief states of drowsiness during the day) to a polyphasic type characteristic of the suckling animal, which presents several periods of drowsiness in the course of the hours.
Studies of recent times, which began with the epidemic of lethargic encephalitis of 1917, have been able to establish that, without disregarding the importance of the cerebral cortex, the subcortical centers have great value in the production of the phenomenon of sleep. Among the authors who have dealt with the question, Demole should be remembered, who in 1921 observed, in the cat, that the injection into the infundibular region of infinitesimal doses of a Ringer's solution, with added calcium chloride, puts the animal to sleep. Hess obtained the same results by means of mechanical and electrical stimulation. Similarly Foerster and Gagel on the one hand and C. Vincent on the other, in the course of surgical operations observed, in man, that mechanical stimulations falling on the floor of the third ventricle, in the perinfundibular region, provoked in the patient an irresistible drowsiness. The localization of this center was subsequently specified by Etors, by Bayley and Harrison, who established it in the region of the posterior nuclei and of the mammillary bodies. It is likely that there exists a center of sleep and one of waking. According to A. Salmon, the posterior pituitary would also have notable importance in the regulation of sleep.
Bibliography8 works
Eleuterio Boganelli
III. ETHICAL AND LEGAL NOTES
During sleep there is per se no responsibility, since the basis for any imputability is lacking, namely the use of reason. At most one may speak of responsibility in cause, if the causes of certain phenomena that occur during sleep were consciously brought about beforehand, for example, in erotic dreams (v. SOGNO) and in seminal emissions during sleep, or if it is a case of artificially induced sleep (v. IPNOTISATO). With regard to seminal emissions during sleep, preceded by erotic dreams, it should be observed that in themselves they are purely physiological and natural phenomena, and therefore not imputable. The state of drowsiness-wakefulness, which precedes or follows deep sleep, is a state in which one does not have the complete use of reason and therefore imputability and responsibility are attenuated.
Sleep is also taken into consideration by law, inasmuch as it deprives the person of the capacity to understand and to will; thus depriving the subject of the legal order of the knowledge and awareness of his own acts, it renders him incapable of giving effect to a legally valid will, of being imputable for his unlawful or criminal conduct. Natural sleep, it is well understood, is the most normal and complete case of incapacity of the person, depriving him of every power of self-determination: indeed it is generally accompanied by an almost absolute inertia and immobility of the body (CIC, can. 2201 § 1; Italian Penal Code, art. 42).
Different is the case of artificial sleep, for which various forms are usually distinguished, and among these hypnosis, narcosis, narcoanalysis (v.), and somnambulism. All of them concern the law according to the degree of lack of free determination of one's own acts that they produce in the subject. And since this is a restriction of liberty, to which the subject is subjected by third parties, the first three forms find their sanction outright in the very Constitution of the Italian Republic, in art. 13. As for the hypnotized person - who acts like an automaton, commanded by others - the law regards him as not imputable for the purposes of the penal norm and incapable of acting for the purposes of the civil norm, if the hypnosis is true and complete. Punishable, on the other hand, will be the one who has induced the hypnosis, or the hypnotized person himself who has submitted to such suggestion in order to commit a crime with impunity (Penal Code, arts. 86, 87, 613; Civil Code, arts. 591, 1425, 2046). Hypnosis for curative necessity is, however, permitted (Penal Code, art. 728).
As for narcosis, which is accompanied by absolute physical immobility, punishable will be anyone who has taken advantage of this artificial sleep for unlawful purposes upon a person (Penal Code, arts. 519 no. 3, 521-579 no. 2). Narcoanalysis, moreover, cannot be admitted in criminal law either as an investigative means or as an expert inquiry (Code of Criminal Procedure, arts. 314, 365), nor can it be considered a judicial experiment (Code of Criminal Procedure, art. 312): it should be remembered that in narcoanalysis the so-called "truth serum" and other drugs are used.
The same things can be said of the sleep of the somnambulist, whom the morbid state allows to perform various acts, but without any will whatsoever, and therefore irrelevant for the law: at most a responsibility may be configured in those who are bound to supervise the behavior of the somnambulist.
Bibliography2 works
Paolo Zamboni