SLEEP. 



the external funftions ? Becavife, during the day, the ani- 

 mal is furrounded with a multitude of excitiiij^ caufes ; a 

 thoufand things exhavift the powers of the ientieat and loco- 

 motive organs, fatigue them, and thus prepare a relaxation, 

 which is favoured at night by the abfence of all itimuh. 

 Thus, in the modern way of life, in which this order is 

 partly inverted, we affemble round us, during the night, vari- 

 ous Itimuh, which prolong the ilate of watchfulnefs, and 

 make the intermiflion of the animal life coincide with the firlt 

 hours of the dawn, favouring it by removing all circum- 

 ftances that might produce fenfations. 



" By multiplying around them caufes of excitation, we 

 can, for a certain time, prevent the organs of the animal life 

 from obeying the law of intermiflion ; but they yield at 

 laft, and nothing, after a certain time, can fufpend its in- 

 fluence. Exhaufted by continued exertion, the foldier fleeps 

 at the fide of the cannon, and the criminal even amid the 

 tortures of the queftion. 



" Let us, however, diftinguifh natural deep, the confe- 

 quence of fatigue of the organs, from that which is caufed 

 by afFeftions of the brain, as apoplexy, or concuflion. In 

 the latter cafe the fenfes are awake, they receive impref- 

 fions, and are affedled by them as ufual ; but thefe impref- 

 fions cannot be perceived by the difordered brain, and we 

 confequently are not confcious of them. In fleep, on the 

 contrary, the intermiflion of aftion affedls the fenfes as 

 much, and even more than the brain." Recherches Phyfiol. 

 fur la Vie et la Mort, p. 34 — 37. 



Although the remarks of Bichat m the preceding quo- 

 tation, refpefting the fleep of the particular fenfes, may 

 be regarded rather as illuftrations, than as proofs that the 

 ftate of fatigue from exertion of any particular organ is ex- 

 aftly the fame as its condition in fleep, we confider the 

 general view of the fubjedl as perfeftly correft. In the 

 moft complete fleep, our relations to external objefts are en- 

 tirely fufpended, and confcioufnefs undergoes an equally 

 complete interruption. The appropriate ftimuli, prefented 

 to the external fenfes, excite no fenfations ; the operations 

 of the mind do not go on ; hence there is nothing to ex- 

 cite volition, and the voluntary powers are confequently 

 quiefcent. The portion of exiilence parted in fuch fleep is 

 a perfeiit blank. We have examples of it in the molt tran- 

 quil and healthy Hates of the body and mind, and after 

 confiderable fatigue, or in the recovery from fevere and 

 painful difeafe. 



But this found fleep is much lefs common, than that 

 which is more or lefs interrupted by dreams, in which a 

 ferics of fenfations, perceptions, and reflections, pafl'es 

 through the mind, as in the waking itate. We are con- 

 fcious of the fame kind of tranfaftions as occupy our wak- 

 ing hours ; we fee, hear, walk, talk, and perform all the 

 cuitomary offices of life. The mind reafon=!, judges, per- 

 forms volition, and experiences the various afiFedlions, as 

 love, hatred, indignation, anxiety, fear, joy, even in a 

 much more lively degree, than when they are excited by 

 their real caufes. In dreaming, as in the foundelt fleep, 

 the attion of the external fenfes is fufpended ; but the in- 

 ternal faculties are aftive in greater or lefs number. Voli- 

 tion tikes place, but the inufcles do not obey the will. 

 That dreaming is a lefs fou.id fpeciis of fleep, appears from 

 the familiar faft, which has pmbably "teen obferved by 

 every individual ; viz. tha'. .he firfl: fleep is much freer from 

 it than the fecund. We retire to rdt, fatigued by the ex-- 

 ertions of the day, and fleep foundly for five or fix hours: 

 we wake, and then fall afleep again towards the morning, 

 and dream the whole time of tliia fecond fleep. 



Haller, who mentions that he had attended much to his 



dreams, obferves, that in perfeft health he remembered 

 only the fenfation of flying throuj;h the air, conceiving him- 

 felf fufpended above the earth and carried to a diitance. 



The order of the images and refleAions, which pafs 

 thr -ugh our minds in fleep, and the laws of their fucceflion 

 and connexions, are the fame as when we are awake. We 

 mult obferve, however, that thefe internal procefles now go 

 on by tliernfclves, and are not coriefted by that referencc 

 to external objects, and that exercife of the external fenfes, 

 which takes place in the waking ftate. Thus we fee a 

 friend long dead, without being aware that he is not alive ; 

 and grofs incorfiilencies and abfurdities take place without 

 being remarked. 



The great activity of the imagination and judgment in the 

 act of dreaming, is evident from the nature of many dreams. 

 " Often," fays Haller, " in my dreams, I feem to read books, 

 printed poema, hiftories of travels, &c. ; and I even fee the 

 plants of diltant regions, fuited to their climates." Others 

 folve problems, write, make verfes, &c. The reafonings 

 which are carried on in fleep, the fpeeches which are made, 

 &c. are often more quickly and eafily performed than when 

 we are awake. 



The caufes of dreams are very obfcure ; we cannot deter- 

 mine how the intellectual po.vers are called into exercife, nor 

 what (limiili fliould be applied for that purpofe. It is known, 

 however, that various bodily derangements have an important 

 influence. The Itate of the ftomach, which fo often afts on 

 the brain, will frequently difturb our reft ; if a perfon, un- 

 accullomed to fuch mdulgence, eat a hearty fupper, he will 

 experience nightmare, that is, a fenfe of prefl^ure about the 

 cheft, and of fome moft dreadful impending danger, without 

 the poffibility of efcaping it. When the painful fenfation is 

 arrived at its height, we awake, and can immediately move. 

 Or the fame caufe, inftead of producing nightmare, may 

 diftrefs us with terrific dreams, in which dangers aflail us 

 in every fliape : we fancy that we cannot efcape from the 

 intricate pallages and rooms of a houfe ; that we ftiall fall 

 from a precipice, or into a river. In thefe inftances, too, 

 fome very ftrong impreffion generally roufes us in 3 ftate of 

 great alarm. Inftances are not wanting of perfons who have 

 determined to remember that the dangers prefented to the 

 mind in dreaming are fallacious, and have recollected this at 

 the time, fo as to be protefted from the alarm, which would 

 otherwife have been caufed. Profeflbr Stewart mentions 

 that Dr. Reid freed himfelf in this way from the diftrefs of 

 frightful dreams, which had annoyed him for fome time. 

 The writer of this article has experienced the lame circum- 

 ftance, and Haller mentions a fimilar faft : " Ita ille, quern 

 diximus, ad vitandas pollutione? voluntatem firmam attuhfie, 

 expergifcebat ad fenfum lubricas imaginis." 



In many bodily diforders, broken fleep, and alarming 

 dreams, which make the patient Hart and awake, are com- 

 mon fymptoms ; fuch is the cafe in hydrothorax, and dif- 

 eafes of the heart. The delirium of fever is an unnatural 

 activity of the internal faculties, the fenfes being more or 

 lefs quielcent, produced by the excitation of the brain, and 

 not diff'enng in its eflential nature from dreams. 



Immediate impreffions fometimes influence us during fleep ; 

 children will evacuate their urine on a chamber-pot being put 

 in their bands ; and the fame effcft is faid to have been pro- 

 duced by puttmg the hand of a flecping child in cold water. 

 The caufe adts more powerfully than it would in the waking 

 ftate ; and the fame remark holds g'^od with refpeft to the 

 excretion of the feminal fecretion in fleep. " Somnium," 

 fays Haller, " quam fer.'.atio fortius eft, et vehementius ani- 

 mam percellit. Id tribuas folitudini, quieti, adtentioni ad 

 unicum objedtum. Certe vix unquam fanus homo ex qua- 



cunque 



