Tài liệu Dreaming - An Introduction to the Science of Sleep pptx

17 3 How is the brain activated in sleep?. 35 4 Cells and molecules of the dreaming brain 53 5 Why dream?. The functions of brain activation in sleep 71 6 Disorders of dreaming 88 7 Drea

An Introduction to the Science of Sleep

J A l l a n H o b s o n i s Professor o f Psychiatry a t Harvard M e d i c a l

School, B o s t o n , Massachusetts H e was the r e c i p i e n t o f the Distinguished Scientist Award o f the Sleep R e s e a r c h S o c i e t y

in 1 9 8 8

His major research interests are the neurophysiological basis of the mind and behaviour; sleep and dreaming; and the history of neurology and psychiatry, with his m o s t r e c e n t w o r k focussing

on the cognitive features and benefits of sleep He is the author

or co-author of many b o o k s , including: The Dreaming Brain ( 1 9 8 8 ) , Sleep ( 1 9 9 5 ) , Consciousness ( 1 9 9 9 ) , Dreaming as Delirium:

How the brain goes out of its mind ( 1 9 9 9 ) , The Dream Drugstore

( 2 0 0 1 ) , and Out of its Mind: Psychiatry in Crisis ( 2 0 0 1 )

U N I V E R S I T Y P R E S S

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author's laboratory at the Massachusetts M e n t a l Health C e n t r e when it was supported by grants for the N I H , N S F , N I D A , and the J o h n T and C a t h e r i n e D M a c A r t h u r Foundation I thank my colleagues for their c o l l a b o r a t i o n and N i c h o l a s Tranquillo for help with the manuscript

1 What is dreaming? 1

2 Why did the analysis of dream content fail to become a

science? 17

3 How is the brain activated in sleep? 35

4 Cells and molecules of the dreaming brain 53

5 Why dream? The functions of brain activation in sleep 71

6 Disorders of dreaming 88

7 Dreaming as delirium: sleep and mental illness 97

8 The new neuropsychology of dreaming 106

9 Dreaming, learning, and memory 119

10 Dream consciousness 133

11 The interpretation of dreams 147

Conclusion 158

Index 161

2 Can dreams foretell the future? 20

3 Do we dream in black and white or in colour? 43

4 Do animals dream? 57

5 When does dreaming start? 73

6 Do blind people see in their dreams? 116

7 Are dreams caused by indigestion? 126

8 What is lucid dreaming? 140

9 Are men's and women's dreams different? 151—2

2 Behavioural states in humans 41

3 The visual brain during REM sleep 60

4 Schematic representation of REM sleep 65

5 How sleep patterns change over our lifetime 77

6 Variation in sleep length 79

7 Autonomic activation in sleep 90

8 Sleep changes in depression 105

9 Data from positron emission tomography ( P E T ) 111

10 Visual discrimination task learning and sleep 125

11 The human brain 135

state of dreaming 18

2 The psychological basis for the differences between waking

and sleeping 26

3 Imaging of brain activation in R E M sleep and the effects of

brain damage on dreaming 109

4 Areas of the brain dealing with the different components

of consciousness 134

5 Alterations of consciousness in dreaming 143

Dr e c o r d e d history As dreaming is so vivid, so c o m p l e x ,

and so e m o t i o n a l , it has inspired religious m o v e m e n t s , artistic representations, and introspective scientific t h e o r i e s All

of these p r e - m o d e r n expressions have b e e n based on the idea that dreams contain messages that c a n n o t be delivered in any other way

T h u s , it was thought by the early J u d a e o - C h r i s t i a n s that G o d

c o m m u n i c a t e d his intentions via c e r t a i n prophets to his human subjects This c o n c e p t was the c e n t r e p i e c e o f medieval d r e a m theory with its postulates o f the ' G a t e s o f H o r n and I v o r y ' Religious r e f o r m e r s such as E m m a n u e l S w e d e n b u r g w e r e able to

m e e t G o d ' s angels in dreams and he t h e r e b y r e c e i v e d i n s t r u c tions about founding the C h u r c h o f the N e w J e r u s a l e m

-Early W e s t e r n artists, such as G i o t t o , used dreaming as a vehicle for the pictorial representation of p r o p h e t i c inspiration Sleeping saints and c h u r c h m e n are shown in t h e same pictorial frame as the visions that their dreams inspired In m o d e r n a r t , the surrealists expressed through their wild paintings t h e c o n v i c -tion that dreaming was a m o r e authentic state of c o n s c i o u s n e s s than waking Salvador D a l i , M a x E r n s t , and R e n e M a g r i t t e all painted in dream language Dali was the m o s t surreal, E r n s t the

m o s t psychoanalytic, and M a g r i t t e the m o s t n e u r o p s y c h o l o g i c a l

o f these artists

A t the turn o f the t w e n t i e t h c e n t u r y , the best known o f all

d r e a m investigators would b e Sigmund F r e u d , w h o set out t o base his t h e o r y o f the m i n d o n brain s c i e n c e His knowledge o f the brain was so i n c o m p l e t e that he was forced to abandon his famous ' P r o j e c t for a Scientific P s y c h o l o g y ' , and he t u r n e d to

d r e a m i n g for insights a b o u t w h a t he c o n s t r u e d to be the dynamic

u n c o n s c i o u s He d e c i d e d , as had all his symbolist p r e d e c e s s o r s , that d r e a m s c o n c e a l e d hidden meanings elaborated as o n e part of

t h e m i n d , and that the u n c o n s c i o u s tried to b r e a k through the

p r o t e c t i v e b a r r i e r o f consciousness Freud thus t h r e w dream

t h e o r y b a c k t o the t i m e o f Biblical scholars, A r t e m i d o r u s , and

o t h e r early i n t e r p r e t e r s o f d r e a m s

T h i s b o o k takes up w h e r e F r e u d left off w h e n he abandoned his P r o j e c t It t r i e s to build a n e w d r e a m t h e o r y on the n o w solid and e x t e n s i v e base of sleep s c i e n c e To accomplish this goal, I have given a c o n c i s e s u m m a r y of the findings of basic brain

r e s e a r c h , sleep lab studies, and r e c e n t clinical studies of sleep and d r e a m s T h r o u g h o u t the b o o k , I use e x a m p l e s taken from my

o w n d r e a m j o u r n a l t o illustrate h o w our n e w t h e o r y o f dreams, called activation—synthesis, can be used to explain in physio-logical t e r m s universal d r e a m features previously ascribed to

p s y c h o d y n a m i c factors O n c e this is d o n e , the mystery of ing is largely stripped away, leaving the c o n t e n t nakedly open to understanding w i t h o u t c o m p l e x i n t e r p r e t a t i o n

dream-T h e main goal of this b o o k is to show h o w a scientific t h e o r y

of d r e a m i n g has b e e n developed and strengthened over the past

SO years In the p r o c e s s , the b o o k offers the reader a unique

o p p o r t u n i t y to r e c o n s i d e r his or h e r o w n dream t h e o r y and, into

t h e bargain, t o l e a r n about the fascinating discoveries o f m o d e r n sleep s c i e n c e

What is dreaming?

What causes dreaming? W h y are d r e a m s so strange?

W h y are they so hard to r e m e m b e r ? A t r u e s c i e n c e

of dreaming requires a reliable definition that can lead to the reliable identification of this state and m e t h o d s of measuring its p r o p e r t i e s D u r i n g the c o u r s e o f w o r k o n the brain, which led to the suspicion that it m i g h t be brain activation

in sleep that causes dreaming, we realized that the m o s t tifically useful way to define and m e a s u r e d r e a m i n g was to focus

scien-on the formal features rather than the c o n t e n t — b y this is m e a n t the perceptual ( h o w we p e r c e i v e ) , cognitive ( h o w we t h i n k ) , and

e m o t i o n a l ( h o w w e feel) qualities o f dreaming, w h a t e v e r the details of the individual stories and scenarios m i g h t b e

T h e radical change in emphasis, from the analysis of c o n t e n t

to the analysis of f o r m , exemplifies what scientists call a digm shift (a rapid change in p a t t e r n or t h e o r y ) T h r o u g h a formal approach, we found an entirely n e w and different way of looking at a familiar p h e n o m e n o n W h e r e a s previously students

para-o f d r e a m i n g had invariably asked ' W h a t dpara-oes the d r e a m m e a n ? ' ,

we asked w h a t the m e n t a l c h a r a c t e r i s t i c s of dreaming are that

distinguish it from waking m e n t a l activity We are not saying that

d r e a m c o n t e n t is u n i m p o r t a n t , uninformative, or even

u n i n t e r p r e t a b l e I n d e e d , we b e l i e v e that dreaming is all t h r e e of

t h e s e things, but it is already crystal c l e a r that many aspects of

d r e a m i n g previously thought to be meaningful, privileged, and

i n t e r p r e t a b l e psychologically are the simple reflection of the

s l e e p - r e l a t e d changes in brain state that we start to detail in

d r e a m i n g with m i n e I q u o t e t h e e n t r y in full I k n o w that you will

d r e a m of s u b j e c t s quite different from m i n e , but I suspect that the f o r m of y o u r d r e a m s is similar

1 0 / 5 / 1 9 8 7 En route to N e w Orleans for a debate on dreams at the

Ameri-can Psychiatric Association's annual meeting: Two nights ago, a dream of Richard Newland

It is a house maintenance nightmare I have too much property to maintain Richard and a friend are 'helping' me but it is an uncertain alliance, with the twin threats of incompetence and inattentiveness There are several scenes all with the same emotional theme: anxiety about maintenance details

In one scene we are walking along in hilly country, perhaps toward the house, but the destination is not clear

Then we are in a house, not at all like mine but assumed by my dreaming brain to be mine, and Richard's friend is spray painting the white wall (we have none in our house) with blue paint (neither do we

have any blue rooms) The paint sprayer is a tank device of the type used

to apply copper sulphate to grapevines or to exterminate cockroaches Suddenly, the paint is being sprayed not only on the wall but upon a painting hanging on the wall

My fears are confirmed I yell at Richard to bid his friend stop

For some reason, he has to go upstairs to turn off the machine (although it appears to be fully portable and self-contained) and this takes an inordinate length of time as the painting continues to suffer There follows a long dialogue with Richard who, while retaining continuous identity as Richard, changes physiognomy repeatedly His face changed as follows: a gnome-like Napoleon Carter with a cherubic sun-burned face; a wry smile and a Chinese coolie-type hat; a calf face—

as in A M i d s u m m e r Night's D r e a m (the ad for which did not include the calf!);and as far as I can tell, never included Richard!

I can't remember other faces or other action from this long episode

B e f o r e discussing the distinctions o f f o r m against c o n t e n t that this dream so clearly illustrates, I should c o m m e n t on the

3

c i r c u m s t a n c e s of its r e c o r d i n g and the timing of its o c c u r r e n c e I was on an a e r o p l a n e , w h e r e I do a g r e a t deal of my j o u r n a l writing I was flying to N e w O r l e a n s for a highly publicized and

w e l l - a t t e n d e d public debate on dreaming I usually r e c o r d

d r e a m s on t h e m o r n i n g after t h e i r o c c u r r e n c e T h e fact that I waited t w o days in this case probably resulted in loss of detail

B u t , as I will presently show, t h e r e is m o r e than enough detail to

m a k e c l e a r the distinction b e t w e e n d r e a m f o r m and dream

c o n t e n t

As far as t h e content is c o n c e r n e d , the dream is about my

c o n c e r n s for the upkeep o f m y farm i n n o r t h e r n V e r m o n t , which

I have o w n e d since 1 9 6 5 R i c h a r d Newland is the son of my

f a r m e r neighbour, Marshall N e w l a n d , with w h o m I have had a long and c o m p l i c a t e d but successful and gratifying relationship

In spite of widely divergent p r i o r i t i e s we have managed to get along and to help each other

F o r m e , t h e m e a n i n g of t h e d r e a m is transparent: I am anxious a b o u t my p r o p e r t y and about entrusting it to people

w h o are careless a b o u t t h e i r o w n houses This characteristic,

k n o w n in psychological t e r m s as e m o t i o n a l salience ( o r

rele-v a n c e ) , is all I n e e d to understand the d r e a m , which is a rele-variant

on the t h e m e of i n c o m p l e t e a r r a n g e m e n t s that is so r e c u r r e n t

in my d r e a m s and in t h o s e of m o s t of my friends For reasons that I discuss m o r e fully in C h a p t e r 2, I see no need and no justification for treating this d r e a m as a disguised, symbolic

e x p r e s s i o n o f anxiety about o t h e r related t h e m e s (my wife's

i n t e r e s t i n a n o t h e r V e r m o n t neighbour, for e x a m p l e ) W h i l e admitting that it could be appropriate and m o r e useful to notice such an association, it does n o t help in understanding what caused this d r e a m , d e t e r m i n e d its c o m i c a l bizarreness, and made

it so hard to r e m e m b e r

Form as opposed to content

To answer the questions about causes and c h a r a c t e r i s t i c s of dreams, it is helpful to take a formal analytical approach

As is typical of m o s t d r e a m s , I am so involved in the s c e n a r i o that it never o c c u r s to me that I am dreaming As I see R i c h a r d Newland (and his unidentified friend), see my house (even though it is clearly n o t m i n e ) , see the blue paint as it is sprayed on the walls, and m o v e through the s e q u e n c e of s c e n e s , I a c c e p t all

of these unlikely features as real on the strength of my atory p e r c e p t i o n s , my delusional beliefs about t h e m , and my very strong feelings of anxiety and apprehension

hallucin-W h a t this means is that our sense of p s y c h o l o g i c a l r e a l i t y —

w h e t h e r n o r m a l dreaming or a p s y c h o t i c s y m p t o m — i s set by the strength of p e r c e p t s and feelings as well as by o u r thoughts about t h e m Internally g e n e r a t e d p e r c e p t i o n s and e m o t i o n s are two formal features of dreams and they are cardinal features To explain their intensity ( c o m p a r e d with w a k i n g ) , we m i g h t

e x p e c t to find that parts of the brain that g e n e r a t e e m o t i o n s and related p e r c e p t s are selectively activated in sleep We see in Chapter S that this is precisely what happens!

My Richard Newland d r e a m is n o t simply perceptually vivid and emotionally salient, it is also cognitively b i z a r r e , by w h i c h I mean that, despite the p e r s i s t e n c e of the main t h e m e s , t h e r e is a

f l a g r a n t disregard for the constancies o f t i m e , p l a c e , and p e r s o n

N o t i c e that R i c h a r d ' s friend is n o t identified; n o t i c e also that the house that is supposed to be m i n e could n o t possibly be s o ; and

n o t i c e that the s c e n e s — h o w e v e r p o o r l y r e c a l l e d and

d e s c r i b e d — m e l d into o n e another: first we are outside walking, then inside painting N o t i c e , m o s t of all, that R i c h a r d ' s face assumes a series of n o n - R i c h a r d features w i t h o u t ever

challenging either the assumption that he is R i c h a r d , or that I am

n o t awake but dreaming, as even a g l i m m e r of self-reflective awareness would declare m e t o b e

T h e s e are the cardinal cognitive features o f dreaming: loss o f awareness o f s e l f (self-reflective awareness); loss o f orientational stability; loss of d i r e c t e d thought; r e d u c t i o n in logical reasoning; and, last b u t n o t least, p o o r m e m o r y both within and after the

d r e a m T h e fact that the incongruities and discontinuities of my

R i c h a r d N e w l a n d d r e a m are c o n n e c t e d by association does not explain the looseness of those associations T h u s , it is true that the unusual spray-painting device r e s e m b l e s an agricultural t o o l ;

it is also t r u e that R i c h a r d ' s t r a n s f o r m e d face is, first, that of

a n o t h e r V e r m o n t f a r m e r neighbour, N a p o l e o n Carter, and later a c a l f ( R i c h a r d and his dairy f a r m e r father, Marshall, had many calves); and it is remarkably t r u e that Shakespeare himself

c e l e b r a t e d the transformation o f c h a r a c t e r s — t u r n i n g t h e m into

e a c h o t h e r and even i n t o a n i m a l s — i n A Midsummer Night's Dream

W h a t causes t h e processing o f such e x t r e m e associations (hyperassociative processing)? F r e u d , like his followers, religiously believed that d r e a m bizarreness was a psychological

d e f e n c e against an u n a c c e p t a b l e unconscious wish This seemed unlikely to many p e o p l e in 1 9 0 0 At the beginning of the twenty-first c e n t u r y , it s e e m s impossible to us

J u s t as we e x p e c t (and find) selective activation of brain circuits underlying e m o t i o n and related p e r c e p t s in rapid eye

m o v e m e n t ( R E M ) sleep, so we seek (and find) selective vation o f brain c i r c u i t s — a n d c h e m i c a l s — u n d e r l y i n g m e m o r y ,

inacti-d i r e c t e inacti-d thought, self-reflective awareness, aninacti-d logical reasoning

You may be m o r e or less pleased by the story You might

p r e f e r t o believe that your dreams are s e c r e t messages o f

personal p o r t e n t B u t w h e t h e r you like the s t o r y o r n o t , y o u must surely be as dismayed as we w e r e to realize that we did n o t really need brain r e s e a r c h to take this formal approach to d r e a m -ing C o m m o n sense alone should have dictated at least that f o r m and c o n t e n t w e r e c o m p l e m e n t a r y T h e distinction is m a d e w i t h ease in o t h e r fields: c o n s i d e r linguistics, w h e r e g r a m m a r and syntax are c o m p l e m e n t a r y ; c o n s i d e r p o e t r y , w h e r e m e t e r and verse enhance o n e another; and c o n s i d e r the visual a r t s , w h e r e genre and subject m a t t e r i n t e r a c t for strong effect S o , why n o t the domain of m e n t a l life itself? W h y n o t in dreams? I s n ' t t h e form o f dreams a n i m p o r t a n t c o n t r i b u t o r t o c o n t e n t ?

As shown in C h a p t e r 2, s o m e brave souls did m a k e this distinction, but their feeble voices w e r e d r o w n e d o u t by t h e

c l a m o u r o f the i n t e r p r e t e r s w h o pandered t o the deep-seated human need to believe that dreaming, as for every apparent mystery, has a deeply veiled m e a n i n g inscribed by a b e n e v o l e n t hand w h o s e ways are k n o w n only to a few c h o s e n m e d i a t o r s

Dreaming and how to measure it

L e t ' s begin our analytical odyssey by a c c e p t i n g the m o s t b r o a d , general, and indisputable definition of dreaming: m e n t a l activity

o c c u r r i n g in sleep B u t what kinds of m e n t a l activity o c c u r in

sleep? Many different kinds, for e x a m p l e :

Report 1 As soon as I fell asleep, I c o u l d feel m y s e l f moving j u s t

the way the sea m o v e d o u r boat w h e n I was o u t fishing today

Report 2 I kept thinking a b o u t my u p c o m i n g e x a m and a b o u t

the subject m a t t e r that it will c o n t a i n I d i d n ' t sleep w e l l b e c a u s e

I kept waking up and was inevitably pulled b a c k to t h e same ruminations about my e x a m

Report 3 I am p e r c h e d on a steep m o u n t a i n t o p ; the void falls

away to the left As t h e c l i m b i n g party rounds the trail to the right, I am suddenly on a b i c y c l e , which I s t e e r through the group of c l i m b e r s It b e c o m e s c l e a r that I make a c o m p l e t e

c i r c u i t of the peak (at this level) by staying on the grass T h e r e is,

in fact, a m a n i c u r e d lawn surface continuing b e t w e e n the rocks and crags

All t h e s e r e p o r t s qualify as descriptions of dreaming ing to o u r broad definition, although they are very different from

accord-o n e a n accord-o t h e r and e a c h is typical accord-of the kind accord-of sleep in which it was e x p e r i e n c e d

R e p o r t 1 contains an internal p e r c e p t , the sense of rhythmic

m o v e m e n t i m p a r t e d by the sea to a b o a t and to those on board the b o a t T h i s r e p o r t is typical of sleep-onset dreams, especially

on nights following novel m o t o r behaviour such as skiing, or

boating, or e v e n — a s in R o b e r t F r o s t ' s poem—After Apple

Pick-ing T h e s u b j e c t has b e e n boating, and the sense of m o t i o n , which

abated i m m e d i a t e l y upon putting his foot on shore, r e c o m

-m e n c e s at sleep o n s e t and r e p r o d u c e s , e x a c t l y , the physical

e x p e r i e n c e of boating We will have m o r e to say later about this stimulus-induced d r e a m , especially w h e n we l o o k at the t h e m e

of m o t o r learning later in the b o o k F o r now, let us emphasize

h o w s h o r t and relatively simple this sleeponset dream e x p e r i

-e n c -e is Ev-en though it is hallucinatory, as is R -e p o r t 3, it is impoverished in its brevity and its n a r r o w s c o p e , its lack of

c h a r a c t e r s o t h e r than the dreamer, and its e m o t i o n a l flatness Many s l e e p - o n s e t d r e a m r e p o r t s are r i c h e r and m o r e variegated than this o n e , although they are all b r i e f and lack the elaborate

p l o t d e v e l o p m e n t o f R e p o r t 3

R e p o r t 2 is limited to thinking, or what psychologists call

cognition T h e r e is no perceptual s t r u c t u r e , and h e n c e no

hallu-cinatory aspect T h e r e is e m o t i o n , however T h e d r e a m e r is

anxious about p e r f o r m a n c e on a test and this anxiety appears to drive obsessive thinking very m u c h in the way that it m i g h t be

e x p e c t e d to do so in waking T h e thinking d e s c r i b e d is n o n progressive T h e d r e a m e r d o e s n ' t even r e h e a r s e the c o n t e n t o f the

e x a m material in a way that m i g h t be adaptive A c c o u n t s of r u m i n ation such as this are often given w h e n individuals are aroused from sleep early in the night If they are c o l l e c t e d in a sleep l a b — a s described in Chapter 3 — t h e y are associated with the l o w levels of brain activation that typify what we call slow wave sleep ( s e e n on the e l e c t r o e n c e p h a l o g r a p h o r E E G ) o r n o n - R E M sleep ( N R E M ; this refers t o the lack o f eye m o v e m e n t ) M e n t a l activity i n N R E M sleep later in the night, w h e n brain activation approaches that seen

-i n R E M sleep, can assume many o f the p r o p e r t -i e s o f R e p o r t 3

R e p o r t 3 is a typical R E M sleep r e p o r t : it is a n i m a t e d ; it is dramatic and c o m p l e x ; it is b i z a r r e ; it is hallucinatory; it is delusional; and it is long, a b o u t eight to t e n t i m e s as l o n g as

R e p o r t s 1 and 2 ( w h i c h w e r e given in t h e i r e n t i r e t y ) , w h e r e a s only a small e x c e r p t of R e p o r t 3 is given h e r e In the r e s t of

R e p o r t 3, t h e r e was a s c e n e change f r o m the m o u n t a i n peak to

M a r t h a ' s Vineyard Island (though I was still on t h e same b i c y c l e ) , and then to a shopping c e n t r e , a restaurant, a d a n c e , and a

m e e t i n g o f faculty colleagues T h e d r e a m also exemplifies typical dream features, such as c h a r a c t e r instability, b e c a u s e o n e of my colleague's wives is seen as a b l o n d w h e n , in reality, she is a

b r u n e t t e T h e sense o f m o v e m e n t , w h i c h i s c o n t i n u o u s , b e c o m e s particularly delightful w h e n I b e c o m e practically weightless and glide along a g o l f fairway At the dance t h e r e is 'a B a l t i c g r o u p wearing e m b r o i d e r e d peasant garb and stamping the floor to a loud band (I can hear the d r u m s e s p e c i a l l y ) '

T h e r e i s simply n o c o m p a r i s o n b e t w e e n the richness o f

R e p o r t 3 and the r e s t r i c t i o n s of R e p o r t s 1 and 2, even though

R e p o r t 2 fulfils this m o r e rigorous definition of dreaming

R e p o r t 3 m o r e fully illustrates a m e n t a l e x p e r i e n c e o c c u r

-r i n g in s l e e p , w h i c h is c h a -r a c t e -r i z e d by:

1 Rich and varied internal percepts, especially sensorimotor ment), auditory (drums), and anti-gravitational (weightlessness) hallucinations

(move-2 Delusional acceptance of the wild events as real despite their extreme improbability (a bike on a mountain peak?) and physical impossibility (gliding weightless on a golf fairway?)

3 Bizarreness deriving from the discontinuity (at least six locations) and character incongruity (a blond brunette?)

4 Emotional intensity and variety (fear, elation, and exuberance)

5 Poor reasoning—I can make a complete circuit of the peak by staying on the grass!

W h e n w e think about h o w the very different e x p e r i

-e n c -e s in t h -e t h r -e -e d r -e a m r -e p o r t s w -e r -e b r o u g h t about, and -ev-en what they may m e a n , we can easily understand the first two simply in t e r m s of brain activation that reflects, in sleep, the

d r e a m e r ' s previous e x p e r i e n c e (the b o a t t r i p ) and c o n c e r n s

a b o u t the future ( a n x i e t y about an e x a m ) In both cases, the residual brain activation of sleep o n s e t and early night sleep is enough to r e p r o d u c e faithfully a very small part of waking

e x p e r i e n c e R e p o r t 3, however, needs a m u c h m o r e elaborate explanation t o a c c o u n t for its description o f events, many o f

w h i c h never happened and never could have happened Brain activation, w h i c h m u s t be powerful, and highly selective, can

a c c o u n t for s o m e a s p e c t s — t h e hallucinatory imagery and the associated m o v e m e n t s , for e x a m p l e B u t activation cannot

Does everyone dream?

All human beings who have been studied in sleep labs have brain activation in sleep Periods of brain activation during sleep are associated with rapid eye movements in the sleeper T h e s e rapid eye movements give the brain-activated phase of sleep its name: REM or rapid eye movement sleep W h e n awakened at the time

of intense clusters of rapid eye movements, 95 per cent of sleepers studied in labs report dreaming From this evidence, it is generally assumed that everyone does, in fact, dream in sleep; any impression to the contrary is related to the difficulty recalling dreams

If dreaming is not interrupted by awakening, it is rare to have recall Poor or no dream recall by many people is a function of the abolition of memory during these brain-activated phases of sleep As the chemical systems that are responsible for recent memory are completely turned off when the brain is activated during sleep, it is difficult to have recall unless an awakening occurs to restore the availability of these chemicals to the brain

a c c o u n t for the b i z a r r e n e s s and t h e loss o f l o g i c a l reasoning I f brain activation w e r e global i n R E M s l e e p , w e w o u l d e x p e c t

o r i e n t a t i o n and c o g n i t i o n t o i m p r o v e , n o t d e t e r i o r a t e T h e s e changes m u s t r e s u l t f r o m s o m e t h i n g e l s e , s o m e t h i n g that changes the w h o l e m o d e o f o p e r a t i o n o f t h e b r a i n and t h e m i n d

As we see in C h a p t e r s 4 and 5, this c h a n g e in m o d e is affected

b o t h c h e m i c a l l y and by selective brain deactivation T h e n e t effect is that, in dreaming ( c o m p a r e d with w a k i n g ) , s o m e mental functions are e n h a n c e d while o t h e r s are diminished I t ' s as sim-ple as that! And every bit as c o m p l i c a t e d

How were dream data collected?

T h e r e p o r t s that have b e e n p r e s e n t e d so far are all m i n e T h e y

w e r e r e c o r d e d a t h o m e o r o n the road i n m y personal j o u r n a l ,

w h i c h n o w runs t o 1 1 6 volumes covering the last 2 5 years o f

m y life and includes over 3 0 0 d r e a m r e p o r t s D r e a m r e p o r t s such as t h e s e have the great advantage of being easy and inexpensive to obtain, n u m e r o u s , and, to me at least, undeni-ably authentic Even though I have no recall of these dreams until I read the r e p o r t s , I have the r e p o r t s and I see in t h e m

t h e striking formal features that I have emphasized in this chapter

T h e s e r e p o r t s d o , however, have c o r r e s p o n d i n g deficiencies,

w h i c h n e e d t o b e o v e r c o m e i f d r e a m s c i e n c e i s t o b e universally valid To test the generality of the findings and to be sure that I

w a s n ' t j u s t m a k i n g up d r e a m s to fit my t h e o r y , we need to have

r e p o r t s from many o t h e r sources and individuals, collected

u n d e r very different conditions T h e dream data that we have analysed b e f o r e arriving at o u r conclusions have thus b e e n taken from o t h e r d r e a m j o u r n a l s , sleep lab r e p o r t s , and home-based

r e p o r t s

Other dream journals

T h e b e s t d r e a m j o u r n a l that I have found is called The Dream

Journal of the Engine Man Its author was a railroad buff I like it

Sleep lab reports

Thanks t o our colleagues M i l t o n K r a m e r ( U n i v e r s i t y o f Cincinnati) and J o h n Antrobus ( C i t y C o l l e g e o f N e w Y o r k ) , and our own sleep lab t e a m , we have o v e r 1 , 0 0 0 r e p o r t s that were c o l l e c t e d by e x p e r i m e n t a l l y awakening participants in studies

W e k n o w that sleep lab awakenings change the c h a r a c t e r o f the r e p o r t s in at least t w o ways

1 They introduce thoughts, feelings, and percepts related to the laboratory situation, but this has no effect on dream hallucinations, delusions, or bizarreness

2 They increase recall and the naturalism of the dream recalled For example, more positive emotion is found in post-awakening reports, indicating that we normally sleep right through our more pleasant dreams, whereas our unpleasant ones are more likely to awaken us and tilt the scales towards negative emotion

A major disadvantage of sleep lab r e p o r t s is that they are very expensive to obtain and tend to c o m e a l m o s t exclusively from younger individuals Students at the universities w h e r e the labs are located are easily r e c r u i t e d Finally, due to

because it was r e c o r d e d in the s u m m e r of 1 9 3 9 ( w h e n I was only six years old) and could n o t t h e r e f o r e have b e e n influenced by

my t h e o r i e s I also like it b e c a u s e the descriptions are so detailed and so free of i n t e r p r e t a t i o n S o m e are even a c c o m p a n i e d by simple but expressive drawings To c o n t r o l for t h e fact that t h e Engine M a n , like m e , is m a l e , we have c o l l e c t e d j o u r n a l i s t i c reports from our female colleagues and students All show t h e same robust formal differences from waking consciousness that I have emphasized h e r e

e x p e n s e , they t e n d t o b e l i m i t e d i n n u m b e r o f r e p o r t s per

p a r t i c i p a n t No o n e w h o is a sleep lab participant can yet

m a t c h the 2 5 6 r e p o r t s o f the E n g i n e M a n , o r m y 3 0 0 +

r e p o r t s

1 Head movement sensor

2 Eyelid movement sensor mount

3 Eyelid sensor lead

4 Eyelid sensor with adhesive backing

5 Bandanna (worn 'pirate style')

6 Wires from sensors to Nightcap unit

7 Nightcap recording unit

(b)

Eyelid movements

Head movements 7:00

F i g u r e 1 Line drawing made from a photograph of a subject sleeping

with the Nightcap, together with Nightcap output and analysis Top trace: histogram plot of eyelid movements; second trace: hypnogram of computer- scored Nightcap data; third trace: histogram plotting head movements

Home-based reports with physiological controls

W i t h the hope o f obtaining the b e s t o f b o t h d r e a m s c i e n c e worlds, we have developed the Nightcap, a h o m e - b a s e d sleep

m o n i t o r that allows us to k n o w what state the participants w e r e

in before their r e p o r t s , to c o m p a r e spontaneous awakening with

e x p e r i m e n t a l awakening r e p o r t s , to obtain abundant data f r o m each p e r s o n , and, b e s t of all, to obtain r e p o r t s in natural settings (Figure 1 ) Using this approach we have b e e n able to a c c o m p l i s h two feats that have never b e f o r e b e e n a t t e m p t e d

O n e is to obtain a very large n u m b e r of r e p o r t s f r o m each of three sleep conditions: sleep o n s e t , N R E M , and R E M sleep T h e other is to obtain c o m p a r a b l e r e p o r t s from t w o states of waking

by beeping the same participants with a h o m e pager during the daytime T h u s , the same participants w h o give us d r e a m r e p o r t s also give us r e p o r t s of their waking consciousness T h i s last advantage is crucial to o u r effort to e x t e n d our understanding of mental life b a c k into the waking state, and to obtain c o m p a r a b l e quantitative data from the minds of the s a m e individuals w h e n awake and asleep

b e t w e e n conscious states, scientists have shied away f r o m t h e i r study because they had no o b j e c t i v e measures of subjective

e x p e r i e n c e and because subjective e x p e r i e n c e was c o n s i d e r e d to

be hard to trust or deal with B u t t h e r e is no substitute for a

d i r e c t approach to h u m a n c o n s c i o u s n e s s , an approach that takes subjective e x p e r i e n c e as data Part of the solution to this prob-

l e m is t e c h n i c a l : we n o w possess laboratory and field methods for establishing the p a r a m e t e r s of brain c o r r e l a t i o n with m e n t a l

e x p e r i e n c e A n o t h e r part of the solution is c o n c e p t u a l : by ing on t h e f o r m a l aspects of m e n t a l states we r e m o v e the distrac-tions and intractability of e n o r m o u s individual differences in

focus-m e n t a l c o n t e n t A s w e see i n C h a p t e r 2 , focus-m o s t o f the i focus-m p o r t a n t differences b e t w e e n waking and dreaming can be captured by

f o r m a l analysis C o n t e n t analysis can thus be unburdened from the impossible task of explaining the formal differences b e t w e e n states o f c o n s c i o u s n e s s

Why did the analysis of dream content fail to become a science?

Although there w e r e a few i m p o r t a n t p r e d e c e s s o r s of the

formal approach to dreaming d e s c r i b e d in C h a p t e r 1,

m o s t dream theorists p r e f e r r e d to focus on c o n t e n t Impressed with the apparent unintelligibility of d r e a m s , these theorists assumed that there was a rebus, or transformational set

o f rules ( a l g o r i t h m ) , w h i c h p r e s e n t e d the d e e p e r meanings o f the dream in disguised s y m b o l i c , m e t a p h o r i c a l , and sensory

t e r m s Interpretation has always b e e n the main goal of c o n t e n t analysis, w h e t h e r for medical diagnosis (in the hands of t h e early

G r e e k s ) , fortune telling (in the w o r k o f A r t e m i d o r u s ) , religious prophecy (in the B i b l e ) , or psychological divinations (in the proto-scientific s c h e m a o f Sigmund F r e u d )

As he was so c l o s e to us in t i m e and spirit, and b e c a u s e o u r brain-based theory is so different from his, in this c h a p t e r we focus on F r e u d ' s psychoanalytic m o d e l as it was developed in his

Project for a Scientific Psychology ( 1 8 9 5 ) and The Interpretation of Dreams ( 1 9 0 0 ) Freud wanted his psychology to have a solid

T a b l e 1 Differences between Freud and activation—synthesis: two models

that offer different explanations of the altered state of dreaming

Instigation Repressed unconscious Brain activation in sleep

wish Visual imagery Regression to sensory Activation of higher visual

Delusional b e l i e f Primary process Loss of working memory

thinking resulting from D L P F C

inactivation Bizarreness Disguise of wishes Hyperassociative synthesis Emotion Secondary defensive Primary activation of

response of ego limbic system Forgetting Repression Organic (physical) amnesia Meaning Actively obscured Transparent, salient Interpretation Needed Not needed

foundation i n b r a i n s c i e n c e , b u t h e was 1 0 0 years t o o early t o

b u i l d i t a s w e n o w c a n F o r this r e a s o n , h e was f o r c e d t o r e s o r t t o speculative p h i l o s o p h y , t h e m e d i u m o f all p r e - m o d e r n d r e a m

t h e o r i e s that analyse c o n t e n t T h e differences b e t w e e n F r e u d ' s

c o n t e n t analytical s c h e m e and m o d e r n t h e o r y are shown i n Table 1

tell the patient things that he would o t h e r w i s e n o t k n o w a b o u t himself All of these systems, including psychoanalysis, are essentially religions in that they are based on faith in an a g e n c y that gives hidden directives, w h i c h can be u n d e r s t o o d only through the i n t e r v e n t i o n o f s o m e o n e w h o can i n t e r p r e t t h e ' m e s s a g e '

Nourishing these ideas was the general assumption that t h e world and its p e o p l e w e r e c r e a t e d b y , maintained by, and beholden to a higher power, a god or gods that c o n s t i t u t e d t h e ultimate agencies o f earthly p h e n o m e n a W h i l e F r e u d was a n avowed atheist—his r e j e c t i o n of religion was practically

p h o b i c — h e fell b a c k into the hidden agency idea with his b e l i e f

in a dynamic unconscious mind that was in c o n s t a n t c o m p e t i t i o n with consciousness In dreaming, this c o m p e t i t i o n b e c a m e w a r -like, so that the m i n d was forced to r e s o r t to e x t r e m e defences to avoid being o v e r w h e l m e d

At a d e e p e r level, all s c h e m e s that analyse c o n t e n t are tially t w o - p r o n g e d : t h e r e are always t w o a g e n c i e s — u s and t h e m , the body and the spirit, the e g o and the id, the brain and t h e mind Part of the change in paradigm exemplified by the shift from dream c o n t e n t to d r e a m f o r m is the adoption of the philo-sophical conviction that the physical w o r l d is the only w o r l d that there is, that the brain and the m i n d are t h e r e f o r e i n e x t r i c a b l y united, and that dreaming is a distinctive f o r m of c o n s c i o u s awareness caused by the state of the brain in sleep To be fair to Freud, we must a c k n o w l e d g e that he really k n e w that these things w e r e t r u e ( o r believed t h e m as fervently as we d o ) , b u t that the interpretive tradition was t o o powerful and t o o t e m p t -ing for him to resist, especially as he k n e w n e x t to nothing about the brain

essen-Still, we can e x p r e s s o u r astonishment at the failure of so

Can dreams foretell

the future?

Since time immemorial, the mysterious nature of dreaming, which we now know is determined mainly by its formal qualities, has led people to believe that dreams w e r e messages from the

o t h e r world Dreams have been regarded as prophetic munications which, when properly decoded, would enable us to foretell the future

com-T h e r e is absolutely no scientific evidence for this theory and considerable scientific evidence against it It is certainly true that individuals who are c o n c e r n e d about a traumatic event, such as the threat of the loss of a loved o n e who is sick, will dream about that loved o n e m o r e than would otherwise be the case

We know from our experiments on lucid dreaming that it is possible to influence dream c o n t e n t simply by having a subject in mind while going to sleep Therefore, dreaming about a loved

o n e at a time when that loved one's life is threatened is not in the least bit surprising If the dreamer then calls and finds that the individual has died, it is understandable for him or her to assume that the dream was a premonition of that death But this

is a mistake It is simply a coincidental correspondence between a situation about which o n e has legitimate and intense concern and the o c c u r r e n c e of the event that o n e fears

We can turn the question around and ask what tutes scientific p r o o f of the o c c u r r e n c e of dreams that are

consti-premonitions (premonitory dreams) T h e answer is that we would need to do what are called prospective studies, studies in which many individuals are sampled in terms of their dream life and judges who know nothing about the dreams or individuals (i.e are blinded) are asked to make predictions or correspond- ences between these dream events and events that occurred in real life A problem that arises here is that individuals who believe

in premonitory dreams will usually give o n e or t w o striking examples of 'hits', but they never tell you how many premoni-

tory dreams they had that w e r e not associated with the event

that in fact occurred To do a scientific study of dream prophecy,

we would need to establish s o m e base of how commonly coincidental correspondences occur between dream and waking reality Until we have that evidence, it is b e t t e r to believe that the assumption is false

d r e a m e d a d r e a m so strange as to pass all understanding', why

d o e s n ' t he go on and c l o s e the c i r c l e by hypothesizing that:

'Because the brain's memory mechanisms are so seriously disrupted during sleep we cannot escape bizarre mental experiences that would otherwise occur only during madness.'

I n d e e d , the analogy with madness offers clues about the

c r e a t i o n o f dreams b y the brain precisely because the f o r m o f

d r e a m i n g is very m u c h like c e r t a i n kinds of madness T h e c o m bination of frequent visual hallucinations (in the perceptual

-d o m a i n ) , instability of o r i e n t a t i o n , an-d r e c e n t m e m o r y loss (in the cognitive d o m a i n ) should have m a d e physicians, such as Sigmund F r e u d and Carl J u n g , r e c o g n i z e that the m e n t a l illness that d r e a m i n g simulated b e s t was d e l i r i u m , the psychosis associ-ated with the acute brain dysfunctions caused by t o x i c i t y (alcohol and d r u g s ) , anoxia (inadequate supply of o x y g e n to the brain caused by circulation deficiencies), and acute head trauma Jung said, ' L e t t h e d r e a m e r awake and you will see psychosis.' Fair

e n o u g h B u t what kind of psychosis will you see? T h e fact that it

is d e l i r i u m should have suggested that a m a j o r shift in brain function was necessary to a c c o u n t for such a major change in

m e n t a l state We r e t u r n to this discussion in C h a p t e r 7

W i t h regard t o m e n t a l state, w e n e e d t o n o t e two i m p o r t a n t points: o n e p h e n o m e n o l o g i c a l , the o t h e r m e t h o d o l o g i c a l

F o r p h e n o m e n o l o g y , the t e r m ' m e n t a l state' implies global features: every aspect of m e n t a l activity changes w h e n the m e n -tal state changes T h e easiest way to effect a global change in

m e n t a l state is to e n g i n e e r a global change in brain state For

m e t h o d o l o g y , the clinical assessment of m e n t a l state has always

b e e n achieved by an e x a m i n a t i o n k n o w n as the mental status

e x a m U n i t i n g n e u r o l o g y and psychiatry, the m e n t a l status e x a m

2 3

is a c o m p r e h e n s i v e c h e c k l i s t of m i n d functions that are k n o w n to

be disrupted by organic brain disease, i e brain disease caused by

a physical rather than a m e n t a l c o n d i t i o n

T o i n t r o d u c e the far-reaching implications o f d r e a m s c i e n c e

to a general s c i e n c e of c o n s c i o u s n e s s , c o n s i d e r the following categories o f the m e n t a l status e x a m :

Even this very i n c o m p l e t e list m a k e s us realize h o w careless

we have b e e n in n o t applying the m e n t a l state c o n c e p t to d r e a m ing and the m e n t a l status approach to its analysis

-B e l o w is a n o t h e r r e p o r t that will help us see t h e global nature of m e n t a l state changes in dreaming:

9 / 3 / 1 9 8 1 Red Car, Dream no 16

I am trying to organize a group for a departure I find one member at the foot of a hill, near some water I urge him to go up the hill to a rendez- vous point for departure

Suddenly, or perhaps always, he is in a red car, which runs along beside me up the hill The peculiar thing is that the front of the car, including the driver, is underground Yet its trajectory is smooth and the ground is unbroken!

As we climb, the car moves ahead of me and I make a strong but vain effort to keep up with its progress The car then crosses from left to right and runs—still half underground—into a wall I wonder if the driver will have hurt his head in the crash

The scene changes

I am in a locker room and approach my son Ian who has been hurt

At first his legs appear to have been amputated at the knees and I feel dread But as 1 approach, what 1 took to be stumps are his blood-smeared kneecaps (very bright red blood—like the car—and he is smiling, not crying) I am relieved and wake up

My consciousness is c l e a r as a b e l l In fact, I s e e — a n d f e e l — everything in this d r e a m with a surreal intensity that would have

pleased A n d r e B r e t o n as m u c h as L e o n a r d o da V i n c i T h e intense

hallucinatory percepts g r i p my attention in a vice that w o n ' t let it

do anything else but w a t c h in f a s c i n a t i o n — a n d in horror—as the

half-buried car h u r t l e s uphill and crashes despite my effort to

c o n t r o l it T h e e m o t i o n s of horror and dread (fear) survive the

s c e n e s h i f t — t o the l o c k e r r o o m — w h e r e I am relieved to find that

my son is O K Although it is n o t explicitly n o t e d , my cognition is defective and my logical reasoning poor H o w could the car do

what it appeared to do and w i t h o u t disrupting t h e g r o u n d ? 'Seeing is believing' is o n e answer

M y R e d C a r dream reveals a n o t h e r kind o f a s s o c i a t i o n — one marked by a high d e g r e e of e m o t i o n a l salience My son, Ian,

was badly injured in an a u t o m o b i l e a c c i d e n t and o n e of his legs was threatened and saved So it is natural for my m e m o r y of

associations—associative m e m o r y — t o link the r e d car crash t o

my son, Ian But (and it is a large but) I do n o t see Ian in the

hospital setting w h e r e I actually b e h e l d h i m at the t i m e of his accident And he had only o n e leg damaged, n o t t w o T h i s departure o f the dream scenario from l o n g - t e r m m e m o r y o f personal e x p e r i e n c e s , called episodic m e m o r y in psychological

t e r m i n o l o g y , is typical and needs to be e x p l a i n e d Episodic

m e m o r y may feed dream c o n t e n t useful fragments for p l o t

c o n s t r u c t i o n , but it does n o t supply the details that are, in waking, so easily r e m e m b e r e d W h y ? W h a t is going on? We should not ignore cases like this b e c a u s e t h e r e is nothing less at stake than how m e m o r y w o r k s This means that d r e a m s c i e n c e is

a set of rules for understanding u n c o n s c i o u s aspects of m e m o r y formation, but n o t in the sense intended by theorists w h o analyse dream c o n t e n t

E x t e n d i n g the suggestions of C h a p t e r 1, d r e a m s c i e n c e n o w needs m u c h m o r e careful consideration o f the n u m e r o u s sub-categories of mental state A list of such subcategories and the ways that n e u r o b i o l o g y explains t h e m are given in Table 2 Having stumbled, almost by a c c i d e n t , on the n o w obvious fact that the bizarreness of dreams is a reflection of orientational instability, w e want t o k n o w m u c h m o r e about o t h e r m e m o r y functions Are declarative a n d / o r episodic m e m o r i e s used in dream plot c o n s t r u c t i o n s ? To what e x t e n t and with what c o n -straints? T h e t e r m s 'declarative' and ' e p i s o d i c ' refer to specific

Disinhibition of networks storing sensory

representations Decreased aminergic modulation

Because of aminergic demodulation, activated representations are not restored in memory

Disinhibition of networks storing mnemonic representations increases access to consciousness Internally inconsistent orienting signals are generated by cholinergic system

m e m o r i e s o f p e r s o n a l o r h i s t o r i c a l e v e n t s , e.g I w e n t t o B o s t o n last w e e k e n d T h i s kind o f m e m o r y i s c o n t r a s t e d w i t h ' s e m a n t i c '

m e m o r y , w h i c h consists o f g e n e r a l facts, e.g B o s t o n i s the capital o f M a s s a c h u s e t t s A n o t h e r class o f m e m o r y i s ' p r o -

c e d u r a l ' , e.g I k n o w h o w t o drive m y c a r t o B o s t o n

A n d w h a t a b o u t thinking? We already k n o w that thinking is suppressed in d r e a m i n g and that it is only slightly effective w h e n

it d o e s appear

T a b l e 2 T h e physiological basis for the differences between waking and

sleeping consciousness T h e causal hypotheses listed in column three are explained later in this b o o k

Function Nature of difference Hypothesis of cause