Evening star., 1938-01-11
STARS, MEN AND ATOMS
Notebook of Science Prosress in F;eld.
Laboratory and Sfudx
l. Laboratory and Study
BY THOMAS r. HENRY.

Finding Of "sleep waves"-a hitherto
unrecorded sort Of brain waves-is re-
ported by DR.. Hallowell Davis and his
associates Of the Harvard Medical
School
These are electrical impulses orieinat-
Ing IN the gray matter Of the cerebral
cortex which can be detected and
measured on the outside of the scalp
Two forms. the alpha and beta waves
are well known The former are BY far
the most common, occurring At q rate
OF about 10 second when . person Is at
rest, preferably with the eyes closed,
and not thinking Of anything. They
are shut of, or greatly diminished, when
there Is any mental activity. The second
are short, low voltage waves which in
some persons occur simultaneously with
the alpha waves and in some seem to
replace them entirely. Both, however,
can be detected only when q person is
awake. There Is . third, and much less
common, delta wave which recurs at
the rate Of from three to five q second
and which Is characteristic of states of
drowisness in normal persons Is well
as OF some mental abnormalities.
The new type of waves recur at the
rate of about II second and make
their appearance only when the subject
Is absolutely asleep. They are, In fact,
diagnostic Of sleep.
DIR. Davis and his associates, Drs. p,
A. Davis, A. L. Loomis, E. N. Harvey and
G. H. Hobart experimental with persons
in the process of going to sleep. These
persons were put to bed In q quiet,
darkened room, with the appropriate
recording apparatus attached to their
scalps. They were instructed to make
an automatically recorded signal by
pressing rubber bulb held In the hand
whenever they awoke or recovered
awareness after dosing.
The first sign of falling asleep an.
peared usually in the falling of of both
alpha and beta waves and the appear-
ance of the slow delta waves. Persons
with well-developed alpha waves often
showed repeated depressions of them
when drifting of to sleep. Just after
such = depression the subject USUALLY
signaled that he had "foated" or
"drifted on" for . minute. The delta
waves usually appeared during the de-
preston intervals. The floating stage, !"
as described by the persons themselves,
always involved loss of awareness for
immediate external stimuli. Some sub
jects, but not all, also described visual
fantasies, hallucinations of movement.
and Interruptions Of logical thought.
Real sleep, DR.. Davis reports. was
regularly signaled, or admitted on SUBJ
sequent questioning, when the delta
waves had reached $50 microvolts or
more and had persisted for a half
minute or more. When the brain wave
record showed bursts of the new waves
with frequency Of II . second. ia
addition to the large delta waves. the
subject was certainly asleep, as Judged
not only from his own subsequent re-
port but from the character Of his
breathing.
From these brain waves experiments
DR.. Davis reported, there seem to be
three distinct stages to going to sleep.
First Is that characterized by the dis
appearance Of the alpha or beta waves.
The subjects themselves were certain
that they still were awaks but thev re-
ported that their minds went blank
for . second or %, they no longer noticed