The Functions of Sleep

298 Pages·1979·4.907 MB·English

by  Rene Drucker-Colin (Eds.)

THE FUNWONS OF SLEEP
edited by
René Drucker-Colin
Departamento de Biologia Expenmental
Institute de Biologia
Universidad Nacional Autonoma de Mexico
Mexico, D.F., Mexico
Mario Shkurovich
Seruicio de Neurofisiologia Clinica
Hospital del Nino, DIF
Mexico, D.F., Mexico
M. B. Sterman
VA. Hospital
Sepulueda, California
and
Department of Anatomy
UCLA School of Medicine
Los Angeles, California
ACADEMIC PRESS New York San Francisco London 1979
A Subsidiary of Harcourt Brace Jouanouich, Publishers
COPYRIGHT © 1979, BY ACADEMIC PRESS, INC.
ALL RIGHTS RESERVED.
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United Kingdom Edition published by
ACADEMIC PRESS, INC. (LONDON) LTD.
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Library of Congress Cataloging in Publication Data
Main entry under title:
The Functions of sleep.
Proceedings of a symposium sponsored by
Hospital del nifto and Universidad Nacional
Autonoma de Mexico, Instituto de Biologia,
Mexico, August 17-19,1977.
1. Sleep—Physiological aspects—Congresses.
2. Sleep disorders—Congresses. I. Drucker-Colin,
René Raul. II. Shkurovich, Mario. III. Sterman,
Barry M. IV. Mérida, Mexico. Hospital del niflo.
V. Mexico (City). Universidad Nacional.
Instituto de Biologia. [DNLM: 1. Sleep-
Physiology—Congresses. WL108 D794f 1977]
QP425.F86 612'.821 78-25669
ISBN O-12-222340-3
PRINTED IN THE UNITED STATES OF AMERICA
79 80 81 82 83 84 987654321
CONTRIBUTORS
Numbers in parentheses indicate pages on which authors' contributions begin.
WILLIAM C. DEMENT (273), Sleep Research Center, Stanford University School of Medicine, Stan­
ford, California.
RENÉ DRUCKER-COLJN (99), Departamento de Biologia Experimental, Instituto de Biologia, Uni­
versidad Nacional Autonoma de Mexico, Mexico, D. F'., Mexico.
FRANCISCO ESTRADA-VILLANUEVA (73), Division de Neurofisiologia, Departamento de Inves-
tigacion Cientifica, Centro Medico Nacional, IMSS, Mexico, D. F., Mexico
AUGUSTO FERNANDEZ-GUARDIOLA (147), Unidad de Investigaciones Cérébrales, Instituto Na­
cional de Neurologia, Mexico, D. F., Mexico.
PETER HAUR1 (251), Department of Psychiatry, Dartmouth Medical School, Hanover, New Hamp­
shire.
ROBERTA. JENSEN (295), Department of Psychobiology, University of California, Irvine, Califor­
nia.
JAMES L. McGAUGH (295), Department of Psychobiology, University of California, Irvine, Califor­
nia.
DENNIS J. McGINTY (171), Veterans Administration Hospital, Sepulveda, California
JOE L. MARTINEZ, JR. (295), Department of Psychobiology, University of California, Irvine,
California.
ALLAN RECHTSCHAFFEN (1), Sleep Laboratory, University of Chicago, Chicago, Illinois
JEROME M. SIEGEL(37), Neurophysiology Research, Veterans Administration Hospital, Sepulveda,
California, and Brain Research Institute, University of California, Los Angeles, California.
HUGO SOLIS (147), Unidad de Investigaciones Cérébrales, Instituto Nacional de Neurologia,
Mexico, D. F., Mexico.
M. B. STERMAN (207), Veterans Administration Hospital, Sepulveda, California and UCLA School of
Medicine, Los Angeles, California.
YASURO TAKAHASHI (113), Department of Psychology, Tokyo Metropolitan Institute for Neurosci­
ence, Fuchu City, Tokyo, Japan.
CARLOS VALVERDE-R. (147), Departamento de Medicina Nuclear y Clinica de Tiroides, Instituto
Nacional de la Nutricion, Mexico, D. F., Mexico.
FRANCISCO VELASCO (73), Division de Neurofisiologia, Departamento de Investigacion Cientifica,
Centro Medico Nacional IMSS, Mexico, D. F., Mexico.
MARCOS VELASCO (73), Division de Neurofisiologia, Departamento de Investigacion Cientifica,
Centro Medico Nacional IMSS, Mexico, D. F., Mexico.
GERALD W. VOGEL(233), Emory University School of Medicine, Sleep Laboratory, Georgia Mental
Health Institute, Atlanta, Georgia.
WILSE B. WEBB (19), Department of Psychology, University of Florida, Gainsville, Florida.
υη
PREFACE
Man has always been intrigued with the process of sleep. When technical means
became available to explore this process scientifically, a systematic search for its
functions was begun. In the context of evolutionary biology, sleep must contribute
to survival and fitness and promote adaptation to environment and reproduction.
Scientists and others assumed that sleep functioned to reverse the ''fatigue" of
sleeplessness, and attempted to define more precisely how fatigue affected the brain
and body and how sleep reversed these effects. That search, however, disclosed a
surprising fact. No matter what aspect of physiology or behavior was examined, its
characteristics were significantly altered as a function of sleep states. While
physiologists and later biochemists explored the basic dynamics exposed by these
findings, clinicians focused on the psychological and medical implications of such
alterations.
The search for function, however, was not entirely abandoned. A major effort
was directed to the study of the effects of prolonged sleep deprivation. Another
surprise was in store. Extended periods of enforced wakefulness did not appear to
produce significant psychological or physical consequences other than sleepiness.
While it was difficult to confirm absolute sleep deprivation in these studies, such
findings threw doubt on the historically popular notion of sleep as an essential
mechanism for reversal of some physiological substrate of fatigue.
The lack of focus on the question of the functions of sleep and the obvious ab­
sence of a simplistic answer to this question led us to organize a symposium on the
topic. Our objective was to bring together an interdisciplinary group of productive
investigators in the field of sleep research whose contributions, past and present,
qualified them as spokesmen on this difficult issue. The meeting was held in August
1977 at Mexico City. This text is an outgrowth of that symposium. The papers
presented address the question of the functions of sleep from a wide variety of
perspectives, examining the developmental, neurophysiological, metabolic, be­
havioral, and clinical correlates of normal and disturbed sleep. Additionally, basic
strategies and subtle pitfalls in the study of sleep functions are outlined in an unusu­
ally comprehensive methodological discussion.
Judging from the diversity of views expressed, it is clear that at least two posi­
tions must be considered. Either we still have failed to grasp the true functional
significance of sleep or, in fact, sleep serves many adaptive purposes. Arguments
presented in these pages appear to favor the latter position. Certainly, many impor­
tant and perhaps fundamental points of view concerning the functions of sleep are
not represented here. For this we apologize, both to their advocates and to the
ix
χ Preface
reader. However, what has been accomplished is a collection of contributions that
focus on this question and depict the state-of-the-art in our quest for its answer. It is
hoped that this compendium will facilitate further inquiry into this fundamental area
of sleep research and discourage a narrow conceptualization of its boundaries.
ACKNOWLEDGMENTS
This symposium was supported by the Hospital del Nino, DIF and by the Uni­
versidad Nacional Autonoma de Mexico. We wish to express our gratitude to
Rosalia Zertuche de Drucker for spending countless hours in the never ending de­
tails necessary for preparing the manuscript. Above all, we are grateful to her for
giving to this book with her good disposition an incredible amount of patience and
attention.
XÎ
THE FUNCTIONS OF SLEEP
THE FUNCTION OF SLEEP:
METHODOLOGICAL ISSUES
ALLAN RECHTSCHAFFEN
Sleep Laboratory
University of Chicago
Chicago, Illinois
All of us who work on the function of sleep
are fortunate to have such a virgin frontier as a
challenge. The functional significance of most
major biological systems such as respiration, cir­
culation, and metabolism is largely understood, but
we do not know why so much of our own lives, the
lives of all mammals and, very likely, submammalian
species as well, should be captured by sleep. The
possible significance of the question almost exceeds
imagination. When the layman asks why we study the
function of sleep, we usually give practical
answers, such as the possibility of learning how
to fulfill the function more efficiently. However,
the function of sleep might have a much deeper sig­
nificance which extends across a large range of
biological phenomena. For example, sleep might
permit periodic readjustments of several biological
systems or parts of a system to optimal relation­
ships with each other; such readjustments might be
difficult during wakefulness when more vigorous
interaction with the environment creates differen­
tial demands on different components. Sleep
function may have unsuspected implications for
health and disease. Now we prescribe sleep like
a folk remedy, but in spite of the age old admoni­
tion for the sick person to get plenty of sleep,
I do not know of a single, well controlled study
which demonstrates that sleep ever helped anyone
get over any malady--except for lack of sleep.
Some day we may be able to prescribe sleep for
specific disorders because we know specifically
what it does. Our current speculations about the
function of sleep may turn out to be petty approxi­
mations of a huge significance that we will not
really appreciate until we are part way toward
the answer.
Copyright © 1979 by Academic Press, Inc.
1 All rights of reproduction in any form reserved.
ISBN 0-12-222340-3
2 Allan Rechtschaffen
Perhaps I do my colleagues an injustice. So­
me of them have offered theories of sleep function
which may be prophetic visions of the truth. But
if they are, these prophesies have not rallied the
faithful. None of these theories have compelled
large numbers of sleep researchers to say "I
believe. Yes, this is the function of sleep." We
wait for more evidence. What kind of evidence?
What do we want? That is what this paper is about
--the kind of evidence we will require to convince
each other about the function of sleep. Our dis­
cussion might well begin with a brief review of
what we mean by need or function and of how we
deal with it scientifically.
THE CONCEPT OF NEED
Although needs or functions may be defined by
empirical measures, these measures are usually
guided by concepts of need. In our effort to
estimate truths beyond what is empirically known,
we are forever generating concepts (i.e., ideas,
hypotheses, theories) which organize and elaborate
upon old facts and hopefully guide us to new facts.
Our ordinary concept of function in biology is that
life processes or interactions with the environ­
ment periodically create states or needs which
threaten the organism's welfare. These needs act
as stimuli for corrective mechanisms which generate
activities or consummatory responses that alleviate
the need.
The success of a concept is evaluated by the
number of different facts which it encompasses--
both old facts and new facts which emerge from
research generated by the concept. The concept of
need has been very successful in some areas. It
has, for example, been able to connect facts about
stimulus conditions (e.g., giving or withholding
of food), organic deficit (e.g., cell damage and
weight loss), behavioral deficit (e.g., motor
weakness), sensing mechanisms (e.g., satiey
centers), consummatory activity (e.g., eating and
digestion), and reversal of deficits after compen­
satory consummation.
Several features of sleep suggest but cannot
guarantee in advance, that it could be success­
fully conceptualized as a consummatory activity:
Methodological Issues 3
the ubiquitousness of sleep across species and
within individuals; the periodic occurrence of
sleep; the effects of sleep deprivation; the re­
versal of deficits after recovery of sleep; the
correlations between sleep and fundamental biolo­
gical parameters (Zepelin & Rechtschaffen, 1974).
To know the function of sleep would mean to iden­
tify with confidence the specific state of mal-
adaptiveness or need which sleep alleviates. A
more complete understanding of the functional
system as a whole would include knowledge of how
this maladaptiveness stimulates sleep mechanisms,
how these mechanisms produce sleep, and what it is
about sleep that alleviates the condition of need.
The relationship between the search for function
and the search for mechanism cannot be decided
a_ priori. Conceivably, considerable understanding
of either could be achieved independent of the
other. One could understand why sleep is adaptive
without understanding how it is produced, and
vice versa. More likely, the two searches would
be mutually enhancing. Clues to mechanisms can
come from knowing the need conditions which should
stimulate the mechanisms and the "directions" in
which the mechanisms had to move to satisfy need.
Clues to function could come from knowing how
mechanisms were activated and the apparent
"directions" in which they were moving. Some may
wonder whether there is merit in invoking the
concept of need at all, whether the whole issue
could not be approached less teleologically in
terms of mechanism alone. Our preferred response
is that function is simply a convenient, short­
hand way of referring to the data of survival and
propagation, the conditions which favor and reduce
them, and the mechanisms of natural selection
which determine the responses to these conditions.
Need really refers to a class of data and
mechanisms, with no mysterious notions of purpose
intended.
The success of a concept depends upon its
interaction with empirical observations. Empirical
information shapes the formation of concepts which
in turn may guide the selection of empirical in­
formation. For example, the concept of need for
food was generated in antiquity by commonplace
observations of relationships among lack of food,
consequent deficits, subjective desires.
4 Allan Rechtschaffen
compensatory consummation, and reversal of deficits
after consummation. These relationships were
sufficiently strong that one could then use any one
of a number of empirical measures to designate the
need" amount of food eaten; reports of desire for
food; weight loss, etc. Each of these manifestly
different observables could be used as a measure of
the theoretical concept of need for food. Almost
inevitably, however, empirical observations arise
which do violence to the concept; they do not fit
into the network of relationships from which need
was inferred. For example, there may be no organ
deficits following prolonged food deprivation, as
in the case of prior obesity, or deficits may occur
in spite of abundant eating, as when one eats the
''wrong foods". At this point one may change the
concept because it does not fit the empirical obser­
vations, or one may reject the discordant observa­
tions under the rationale that in some situations
empirical data may yield poor estimations of the
concept. The best outcomes are when concepts or
measures or both can be changed to become more
concordant, e.g., as when the need for food becomes
identified more specifically as a need for certain
nutritional substances. Under this revised concept,
food intake per se becomes only a very crude and
sometimes misleading indicator of the revised
concept of need for nutritional substances.
The important point for us now is that the
choice of empirical referents for the sleep need
can sometimes be very misleading, not only with
respect to what that need may eventually turn out
to be, but also in the initial recognition of when
a state of need exists. In some cases the choice
of empirical referent may do violence to the very
concept of need itself. We will try to illustrate
these problems more specifically later, but first
we may take note of the problems which arise from
the limitations of empirical data.
EMPIRICAL INFORMATION
Fundamentally, the scientist gathers three
kinds of empirical information; each has its
intrinsic limitations. 1. Description. This
includes the selection of target phenomena, develop­
ment of the methods of reliable measurement, and
organization of the observations for public pre­
sentation. The choice of phenomena to be described
as indicative of need for sleep is largely a matter