2 30 THE POPULAR SCIENCE MONTHLY. 



THE CHEMISTRY OF SLEEP. 



By HENEY WURTZ, Ph. D. 



WE do not comi)reliend the mystery of wakeful conscious- 

 ness; and therefore that of temporary unconsciousness, 

 including sleep of all kinds, is equally beyond our understanding. 

 To say that sleep is a suspension of our control over our thoughts 

 and our motor nerves and voluntary muscles is a mere substitu- 

 tion of other classes of mysteries equally inscrutable. 



The same should be frankly admitted as to all our so-called 

 explanations of natural phenomena, which consist mainly of gen- 

 eralizations, expressing in few words the laws that rule and con- 

 nect, so far as we can discover, the infinity of cosmical facts and 

 transformations. Such generalizations whose surpassing im- 

 portance and value are nevertheless undeniable imply, as essen- 

 tial preliminaries, the laborious classification of the facts in any 

 field of investigation that we have in hand. 



But in the field of which we are now to attempt a brief and 

 necessarily superficial survey it must be conceded that such classi- 

 fication is as yet highly imperfect. The forms and modifications 

 of existence varying in cause or origin, nature, and degree which 

 may be called by the general name of sleep have not yet been 

 subjected to the exact and critical experimental research needed 

 for scientific classification. Little can now be done except to 

 point out wherein our knowledge is defective, and to indicate 

 some more or less tentative arrangement of the facts under differ- 

 ent heads as a provisional guide to the study of this condition of 

 existence, in which mos persons expend one third of their terms 

 of life. Such heads may be as follows : 



An attempt at a definition of normal healthy slumber, which 

 only is entitled to be called 



"Tired Nature's sweet restorer, balmy sleep." 



Such a definition must be sufficiently well founded on the con- 

 ditions presented in natural sleep to admit of drawing lines of 

 parallelism with and of divergence from other species of lethargy 

 or unconsciousness, or modified consciousness, that arise from 

 abnormal or morbid conditions, mental and nervous disorders, 

 drugs, anaesthetics, cold, heat, exhaustion, partial asphyxiation 

 by drowning or otherwise, etc. 



A statement of our present narrow range of facts and observa- 

 tions relative to the chemical, physical, and physiological changes 

 of the organs of the body, and of their functions, during normal 

 sleep. 



A consideration of the mental, moral, and emotional phenom- 



