SLEEP SLEEPLESSNESS. 499 



sound asleep on losing a large quantity of blood, a proportion being, of course, drawn 

 from the brain. Most people have noticed the influence of heat that of the fire, 

 for example in causing drowsiness, and eventually sleep, if sufficiently prolonged. 

 During the prevalence of high temperatures the blood flows in increased proportion 

 to the surface of the body, and consequently the quantity in the brain is diminished. 

 A slight degree of cold excites wakefulness at first ; but if the constitution be strong, 

 the effect is to favour the production of sleep. This it does by reason of the deter- 

 mination of blood to the surface of the body which moderate cold induces in th 

 vigorous. The ruddy complexion and the warm hands and feet produced in such 

 persons under the action of this influence are well known. If, however, the cold 

 be very intense, or the reduction of temperature sudden, the system even of 

 the strongest fails to resist it, and then a very different series of phenomena result 

 Stupor, not sleep, is the consequence. The blood-vessels of the surface contract, 

 and the blood accumulates in the internal organs, the brain among them. Many 

 instances are on record showing the influence of extreme cold in the production 

 of sleep, or rather stupor. One of the most striking is given in Captain Cook's 

 "Voyages," in regard to an excursion undertaken by Sir Joseph Banks, Dr. 

 Solander, and nine others, over the hills of Terra del Fuego. Dr. Solander, knowing 

 from his experience in Northern Europe that the stupor produced by severe cold would 

 terminate in death unless resisted, urged his companions to keep in motion when they 

 began to feel drowsy. " Whoever sits down" said he, " will sleep, and whoever sleeps 

 will wake no more" Thus, at once admonished and alarmed, they set forward ; but 

 they had not gone far before the cold became suddenly so intense as to produce the 

 effects that had been most dreaded. Dr. Solander was the^rs^who found the inclination 

 against which he had warned others invincible, and he insisted on being suffered 

 to lie down. Mr. Banks (as he was then) entreated and remonstrated with him in 

 vain ; down he lay upon the ground, although it was covered with snow, and it was 

 with much difficulty that his friends kept him from sleeping. Richmond also, one 

 of the black servants, began to linger in the same manner ; when he was told that if 

 he did not go on he would in a short time be frozen to death, his answer was that 

 he desired nothing but to lie down and die. The Doctor said he was willing to go 

 on, but that he must first take some sleep ; although but a short time before he had 

 told the company that to sleep was to perish. It was found impossible to carry them, 

 'and there being no remedy they were both at length suffered to lie down, being partly 

 supported by some bushes, and in a few minutes they fell into a profound sleep. 

 Soon after some of the people who had been sent forward returned with the welcome 

 news that a fire was kindled about a quarter of a mile ahead. Mr. Banks then 

 endeavoured to wake Dr. Solander, and happily succeeded ; but though he had not 

 slept five minutes, he had almost lost the use of his limbs, and the flesh was so 

 shrunk that his shoes fell from his feet. He consented to go forward with such 

 assistance as could be given him, but no attempts to relieve the servant were 

 successful. He, together with another black left with him, died. 



Another potent cause of sleep, and one of which we habitually avail ourselves, is 

 diminution of attention. Shutting the eyes so as to exclude the light, getting 

 beyond the sound of noises, refraining from the employment of the other senses, and 



