American citizen. [volume] (Canton, Miss.) 1864-1890, 1873-02-22
Sleep.

IHE history OF the opinions OF physlOlO.
gists in regard to the cause of sleep pre-
sents an instructive example of the folly
of theoriZing on such a subject, in the
absence of any adequate basis of facts es-
tablished by observation. From the good
old times, when the ascension of vapOrs
from the stomach, their cOngelatiOn by
the GOODNESS of the brain, and the cOnse-
quent plugging of the vessels of the head
was deemed quite lucid and satisfactory
account of the matter, down to a cOmpar-
atively recent period, there have been in
Vulnerable opinions in regard to the cause
of sleep. The latest writer on the sub
ject, when setting up his own theory, de-
molished without difficulty those of his
predecessors. At last the balance of
scientific opinion, after many uncertain
oscillations, settled pretty steadily down
to the conviction, that the proximate
cause of sleep is state of fulness or dis
tension of the bloOd-vessels of the brain.
Slumber is brought about, it was believed,
by pressure of the distended vessels on
the brain tissue. Though some men of
high standing could not repress their
doubts that natural sleep is not caused in
this way by tight sanguineous nightcap,
this opinion was generally held, and the
doubters could not give any better solu-
ton of the problem, but were rather in
clined to treat it as insoluble. One thing
was certain: that a condition in some re-
spects resembling sleep could be artifici-
ally produced by pressure on the brain.
This condition, though often identified
with sleep, was really its counterfeit,
coma or stupOr, state distinguishable
from true slumber by the great difficulty of
arOusing the unfortunate subjects of it.
This theory, after it had long held sway,
was at last proved to be at variance with
some established physiological principles,
and with observations made on the brain
vuyI,n hot hoH hlQ
posed by fracture of its bony covering. 1t
was shown, besides, that state in every
way resembling natural sleep could be in
duced by diminishing instead of increas-
ing the supply of blood to the brain. In
1855, it occurred to DIR. Fleming, then a
professor in Cork, to try the effect of COM
pressing at the upper part of the neck the
carotid arteries. two of the vessels which
convey the vital fluid to the brain. He
requested friend to make the experiment
on himself. The result was the prOduc-
ton of a state of complete unconscious
ness, in which, however, the subject of
the somewhat hazardous experiment
dreamed with great activity, a few Sc
cOIIds appearing as hours, from the num-
Der and rapid succession of the thoughts
passing through his mind. The effects
passed off on the removal of the pressure
from the vessels. This was clearly a
very different condition from that OF
stupor, and one not distinguishable from
ordinary sleep. DIR. F leming was cautious
in drawing conclusions, but he threw out
the suggestion that possibly after all Or
binary sleep might be connected with an
opposite cerebral condition to that COM
monty assigned as its cause. In few
years this was placed beyond all doubt.
Mr.. Durham, a London surgeon, and al
most simultaneously DR.. Hammond of
New York, showed, by a series of ext eri-
ments on the lower animals, the results
of which were first published in 1SGO, that
during sleep the brain is in a compare
lively bloodless condition. The expert
mentors observed the brain becoming
pale, and sinking down as sleep came on ;
and as that condition passed off, they saw
its surface rising up and becoming suffused
with the red blush of the returning cir
culation. At the period of complete
awakening the vessels became more full
and distended, and a large number sprang
into sight which had been invisible dur
ing slumber. These experiments, when
viewed in connection with that of D..
Fleming, formerly mentioned, proved
conclusively that the immediate antece-
dent of sleep is diminutiOn of the stream
of blood flowing to the brain, which con-
dition lasts curing the continuance OF
sleep.-Chamber's Journal.