240 



DISCOVERY 



craving for sleep, and they slept standing, with their 

 heads falling over the parapet ; slept sitting, hunched 

 in ditches ; slept like dead men where they lay in the 

 open ground. In body and brain these men of ours 

 were tired to the point of death. WTien called upon 

 to make one last effort after six days and nights of 

 fighting and marching, man}' of them staggered like 

 men who had been chloroformed, with dazed eyes and 

 grey, drawn faces, speechless and deaf, blind to the 

 menace about them." This is an excellent description 

 of the results of fatigue poisoning of the brain cells. 

 It was so profound that the centres for hearing, seeing, 

 and speech were benumbed, or as though narcotised. 



The late Mr. Stevens told us how the camel-drivers 

 in Lord Kitchener's famous forced march to Khartoum, 

 overcome with fatigue, fell from the camels and slept 

 on the sand while the rest of the Army Corps thun- 

 dered past them. Sentries thoroughly fatigued have 

 fallen asleep on their feet and remained standing ; 

 postillions, in the good old coaching days, often fell 

 asleep on horseback and yet rode on in the saddle. 

 We recall that de Quincey wrote his " Vision of 

 Sudden Death " after having been driven at thirteen 

 miles an hour by a driver fast asleep on the box seat 

 of a mail coach. More than once the cross-Channel 

 swimmer, Holbein, has been noticed by the men in 

 the boat to be swimming asleep. A friend of my own, 

 a Colonel of Volunteers, told me that after undergoing 

 twenty-two hours of extreme fatigue after the Great 

 Review at Edinburgh in 1881, he walked home sound 

 asleep for several miles along a familiar road in 

 Fifeshire. This is not the so-called^ somnambulism, 

 it is co-ordinated muscular activity during chemically 

 induced sleep. A similar experience is related in 

 Kipling's Stalky and Co. : " After that I went to 

 sleep ; you can, you know, on the march, when your 

 legs get properly numbed : Mac swears we all marched 

 into camp snoring and dropped where we halted." 



Extreme misery, stimulation, or the endurance of 

 long-continued pain finally brings on sleep. In the 

 good old days of torture, people used to fall asleep 

 on the rack. A vivid instance of sleep after prolonged 

 physical and mental pain — " bullying" — is also given 

 in Stalky and Co. : " When Fairbairn had attended 

 to me for an hour or so, I used to go bung off to sleep 

 on a form sometimes." These sleep-producing fatigue 

 substances have not been identified by physiologists, 

 though attempts have been made to isolate them. 



Whatever their exact chemical nature may be, 

 there is no doubt that they are similar in action to the 

 well-known vegetable alkaloidal poisons, morphine, 

 nicotine, curare, and atropine, substances which inter- 

 fere with the passing of impulses over the cell units of 

 the nervous system. Hence there is related to this 

 chemical factor in normal sleep the pathological type 



of sleep due to drugs — narcosis — whether the drug 

 be bromides or ether, chloroform, alcohol, chloral, 

 sulphonal, or any of the newer hypnotics ; hypnosis 

 being but the Greek for "putting to sleep." 



Lastly as to this factor we have the insomnia or sleep- 

 lessness from being " too tired to sleep.' ' This insomnia 

 may be due to the discomfort or pain arising from 

 the over- exercised muscles, tendons, and ligaments, 

 but some of it is due to the fatigue substances having 

 an irritant instead of a hypnotic effect on sensory cells. 

 Shakespeare, in the famous passage in King Henry IV 

 (Act III, sc. i), has contrasted the sleeplessness of 

 the King owing to cares of state with the sound sleep 

 of his humble subjects and also with the fatigue- 

 produced slumbers of the tired-out sea-boy in such 

 majestic language that the quotation of the lines will 

 be pardoned ; 



"How many thousand of my poorest subjects 

 Are at this hour asleep ! O .sleep, O gentle sleep, 

 Nature's soft nurse, how have I frighted thee, 

 That thou no more wilt weigh my eyelids down 

 And steep my senses in forgetfulne.ss ? 

 Why rather, sleep, liest thou in smoky cribs. 

 Upon uneasy pallets stretching thee 

 And hush'd with buzzing night-flies to thy slumber. 

 Than in the perfumed chambers of the great. 

 Under the canopies of costly state. 

 And lull'd with sound of sweetest melodv ? 



Wilt thou upon the high and giddy mast 



Seal up the ship-boy's eyes, and rock his brains 



In cradle of the rude imperious surge ? 



Canst thou, O partial sleep, give thy repose 

 To the wet sea-boy in an hour so rude. 

 And in the calmest and most stillest night 

 Deny it to a king ? Then happy low, lie down, 

 Uneasy lies the head that wears a crown." 



(2) Absence of Sensations 



The second factor productive of sleep is a negative 

 one, the absence of sensations. Everyone knows we 

 get off to sleep best when we retire into the dark, 

 shut our eyes, and exclude as perfectly as we can the 

 distracting sounds of the outer world. Rarely can we 

 sleep in a bright light or in a noise, or if we are suffer- 

 ing pain ; sensations must be minimised or abolished. 

 As we have just seen, in the sleep of extreme fatigue 

 sensations are disregarded, but ordinary somnolence 

 is brought about by a mild degree of fatigueco-operating 

 with the more or less complete abolition of sensations. 

 Any sensory stimulation can keep us awake — being 

 too hot or too cold, or finding the bed- clothes too light 

 or too heavy, or, of course, being in pain. This is 

 the insomnia related to this second type of sleep. 

 Cold feet — our own or someone else's — are a famihar 

 cause of sleeplessness. 



The onset of sleep as due to the withdrawing of 



