New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1898-05-22
WHAT MAKES PEOPLE SLEEP
SOME OF THE CURRENT THEORIES ON
THIS PULLING SUBJECT.

HAS THE WITHDRAWAL OF BLOOD FROM THE
BRAIN ANYTHING To Do WITH Ir7-oTHER
EXPLANATIONS DISCUSSED.
There is scarcely any human experience that
Is ut the same time common and yet 80 much
Of a mystery sleep. great variety OF theo-
ries have been advanced to explain the phe-
nomenon. but IA yet not one gives thorough
satisfaction TO the scientists. to say nothing CT
the general public. which often has its own
notions about such things. recent writer IN
Mature" says that no explanation has received
so wide credence as the absence OF blood from.
or anamia Of. the brain. But he goes on to
mention several reasons why that theory IS not
altogether acceptable.
No doubt the belief that sleep was Induced
by the withdrawal Of blood from the brain arose
from the discovery. which is undsputed. that
the volume of that organ is sensibly dimin-
.shed during sleep 1t is also an established
fact that there is less blood there when one Is
asleep than when he Is awake. But the writer
referred TO holds that these are merely attend
ant circumstances, and not causes.
He points out TO begin with that the c!rcu-
lation Of blood In the brain depends hot on
special excitation as In other parts OF
the body but on the pressure in the arteries Of
the whole system. II IL then asserted that this
pressure is regulated largely by The physical
activity OF a person. The pressure Is higher
II man walks brskly than II he is engaged
In quiet thought but lying down. The fall OF
pressure then appears TO be an accompani-
ment 81 rest rather than Of sleep. Further
more It has been found that although one an
aesthetic agent. choroform. reduces the guam
tity Of blood in the brain. others, notably ether
or a mixture OF nitrous oxide and oxygen fail to
produce that effect. And II IL still further urged
that fatigue does not. as was once believed. re-
duce the arterial pressure. The latter Is now
attributed TO inactivity or rest.
Here are some Of the phenomena that at
tend sleep The breathing becomes shallow.
the amount Of air inspired is lessened. the out
put OF carbonic acid gas is likewise diminished.
the bodily temperature falls the muscles are re-
liked. and consciousness Is suspended. 1t is
argued in Nature" that II is no more prope.
To say that the che last mentioned is any more
due to anmma Of the brain than are the others
II has been suggested that there is a chemical
effect Of fatigue which induces sleep: that
fatigue robs the brain OF a certain store OF
oxygen. or deposits alkaloida substances that
clog It's action. and 80 brings unconscious
ness The anonymous writer here cited does
facts that he mentions by way Of disproof is
that overfatigue is likely prevent sleep
Recent additions TO the knowledge Of the
structure and behavior OF the central nervous
system have given rise to still another theory.
II has been thought TO be possible that certain
dendrtes or mosske projections from the
nerve cells. are contractile and reach out and
meet 10 produce consciousness and other mental
phenomena when the brain is fresh but draw
back and break the connection when that organ
is weary Regarding this idea. Mature" says:
The difficulty of accepting II is that nobody
can locate consciousness In any particular group
of nerve cells Moreover the anatomical evil
dence Of such changes taking place is at present
OF the fiimsiest character.
II these theories be true. what. II may be
asked Is the agency that causes the dendrtes
TO contract? Is there really soul sitting aloof
I'm the pinea gland. as Descartes held? When
a man like Lord Brougham can at any moment
shut himself away from the outer world and
fall asleep does his soul break the dendritic
contacts between cell and cell; and when ne
aWakes does II make contacts and switch the
impulses evoked by sense stimuli on to one or
other tract Of the axons, or axis cylinder proc
esses which form the association pathways?
Such nm hypothesis Is no explanation; II simply
puts back the whole question step further.
and leaves 1t wrapped In mystery. 1t cannot
be fatigue that produces the hypothetical in
terruptons Of the dendritc interlacings and
then induces sleep. for sleep can follow after
fatigue Of very limited kind man may
sleep equally we'll after a day spent In scien.
tifc research as after one spent In mountain
climbing or after another passed In idling by the
seashore He may spend whole day engaged
In mathematical calculation or in painting a
landscape He fatigues--if We admit the To-
caization Of function to definite parts OF the
brain-but one set Of association tracts. but one
group OF cells and yet. when he falls asleep.
consciousness IS not partially but totally sus-
pended.
The primary and immediate cause Of sleep
seems to be the withdrawal or cessation Of slim
Vii to the senses II there 10 only gentle ana