Harvard Medical SchoolHarvard Medical SchoolBeth Israel Deaconess Medical CenterBeth Israel Deaconess Medical Center

Boston, MABoston, MA

Harvard Medical SchoolHarvard Medical SchoolBeth Israel Deaconess Medical CenterBeth Israel Deaconess Medical Center

Boston, MABoston, MA

Sleeping on a Problem: Where Insight is Expected Sleeping on a Problem:

Where Insight is Expected

Robert StickgoldRobert StickgoldRobert StickgoldRobert Stickgold

InsightInsight

“The sudden appearance in conscious awareness of a new and useful relationship among previously known information”

“The sudden appearance in conscious awareness of a really big new and useful relationship among previously known information”

Questions: How does the nonconscious brain find these

relationships? How does it identify them as valuable? How does it bring them into conscious awareness? Should we only consider the “really big” ones?

“Really Big?”“Really Big?”

Normal science: "Curiosity demands that we ask questions, that we try to put things together and try to understand [them]... In this way we try gradually to analyze all things, to put together things which at first sight look different, with the hope that we may be able to reduce the number of ‘different things’ and thereby understand them better.”

Richard Feynman (1963) "The Feynman lectures on physics"

“Really Big?”“Really Big?”

”Scientific revolutions are inaugurated by a growing sense ... that an existing paradigm has ceased to function adequately in the exploration of ... nature.” Entrenchment reduces possibility of shifting

Thomas Kuhn (1962) "The Structure of Scientific Revolutions"

Or Not So Big?Or Not So Big?

Piaget proposed that children learn by constructing a model of the world built of “schemas” that explain how parts of the world work.

Assimilation (like normal science) integrates new perceptual information into innate or personally developed schemas (“robins”) (Children are biased to fit data into schemas)

(Piaget, 1981)

Or Not So Big?Or Not So Big?

When assimilation fails (“penguins”) accommodation modifies the schemas “to fit reality”

(Piaget & Inhelder, 1969, p. 6)

So, big or small, the process of insight is probably fundamentally the same.

Sleep & InsightSleep & Insight

Insight, then, whether related to large or small discoveries, is a special case of Piagetian accommodation in which the process occurs outside of conscious awareness.

Obviously, this process of accommodation (and insight) is defined by the innate wiring and functional plasticity of the human brain.

The processes of brain plasticity necessary for Piagetian accommodation, and hence for insight, may be most daringly activated, not during wake, but during sleep.

There are Different Kinds of Sleep

There are Different Kinds of Sleep

A Good Night’s SleepA Good Night’s Sleep

11 PM 1 AM 3 AM 5 AM 7 AM

Wake

I/REM

II

III

IV

Sleep onsetSleep onset

Stage 2 NREMStage 2 NREM

SWSSWS

REM sleepREM sleep

Sleep PhysiologySleep PhysiologyEEG

Wake

Stage 2

Stage 4

REM2 sec

EOGStage 1

Stage 2

REM

EMGWake

Stage 4

REM

Neuromodulation Varies Across the Wake-Sleep Cycle

Neuromodulation Varies Across the Wake-Sleep Cycle

Active Wake

ACh

NE5-HT

Quiet Wake

SWS REM

Ach: acetylcholine (scopolamine, belladonna)NE: norepinephrine (MAO inhibitors, cocaine)5HT: serotonin (Prozac, LSD)

Regional Activation in REM SleepRegional Activation in REM Sleep

Hippocampal-Neocortical DialogHippocampal-Neocortical DialogNeocortex

Hippocampus

There are Different Kinds of Memory

There are Different Kinds of Memory

Sleep Alters Associative Memory Systems

Sleep Alters Associative Memory Systems

• Cindi Rittenhouse• Jen Holmes• Beth Schirmer• Lauri Scott

Semantic Priming

(580 ms)thief wrong

(560 ms)right wrong

paper wrong (600 ms)

0.01 0.17 0.01

Weak

Strong

mse

c

0

10

20

30

REMNREM PM

Sleep Enhances InsightSleep Enhances InsightNumber Reduction TaskNumber Reduction Task

11 11 44 44 99 44 99 44

11 44 44 11 999911

• Ulrich Wagner• Jan Born

Wagner et al. (2004) Nature 427: 352

Development of InsightDevelopment of Insight

Wake/Night

Wake/Day

Sleep/ Night

0%

20%

40%

60%

Su

bje

cts

gai

nin

g i

nsi

gh

t

I

mp

rove

me

nt

in s

pee

d (

ms)

0

100

200

Solvers Non-solvers

SW

S

SW

S

11 11 44 44 99 44 99 44

11 99 11 44 44 11 9999

• Ina Djonlagic• Andy Rosenfeld• Mark Gluck

Sleep Calculates the Rules

Sleep Calculates the Rules

?!?

QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.

Probabilistic LearningProbabilistic Learning

Card 1 Card 2 Card 3 Card 4

80% 60% 40% 20%

Practice & Sleep Enhance PerformancePractice & Sleep Enhance Performance

0

2

4

6

8

10

12

14

p = 0.01

Observation

Impro

vem

ent

(% o

f tr

ials

)

Wake

Sleep

Feedback

p = 0.06

Weather Forecasting & REM SleepWeather Forecasting & REM Sleep

15%

17%

19%

21%

23%

25%

55 65 75 85 95

Post-Training Performance (% of optimal)

REM

Sle

ep (

%)

r = 0.70p = 0.008

• Jessica Payne• Ruth Propper• Daniel Schacter

Word ListsDoor House LedgeGlass Open BreezePane Frame CurtainShade View

Sleep Enhances the Gist

Sleep Enhances the Gist

12-Hour Deterioration12-Hour Deterioration

15

0

-15

-30

-45

-60 Critical lures

Studied words

*

% C

han

ge (

rela

tive

to 2

0 m

in

Wake

Sleep

*

5

15

25

35

10 15 20 25

SWS (%)

Word

s R

eca

lled

Morning RecallMorning Recall

r = -0.47p = 0.03

60 Nap

0

10

20

30

40

50

0 10 20 30 40 50

SWS (min)

words

Morning & Nap RecallMorning & Nap Recall

r = -0.47p = 0.03

Overnight

words

SWS (min)

0

40

10

20

30

50

10040 60 80 120

r = -0.54p = 0.037

Creative IntrusionsCreative Intrusions

WordWord ListList

PlatePlate CupCup

SpoonSpoon CupCup

FuzzyFuzzy

SwirlSwirl

BloodBlood DoctorDoctor

Rough? Smooth?Rough? Smooth?

Soft? Mountain??Soft? Mountain??

0%

20%

40%

Wake

Perc

en

t of

Intr

usi

on

s

Sleep

Creative IntrusionsCreative Intrusions

New Experiences are Replayed at Sleep OnsetHypnagogic dreams

New Experiences are Replayed at Sleep OnsetHypnagogic dreams

• Erin Wamsley• Karen Emberger• Laura Babkes

Alpine Racer IIAlpine Racer II

• 14 out of 16 players (88%)14 out of 16 players (88%)• 42% of first night reports contain skiing 42% of first night reports contain skiing

imageryimagery• 3 out of 3 controls who only watched3 out of 3 controls who only watched

Alpine Racer ImagesAlpine Racer Images

““I keep seeing all the places where I fall- like, hit the walls. It’s kind of annoying; and then my legs fly up in the air.” (SEC)

“I can sort of feel the motions of the game but more not really seeing it.” (MLC)

“I envisioned myself skiing, and for a second there it felt like I was skiing backwards - something I used to attempt when I was younger.” (CMD)

Delayed Onset ReportingDelayed Onset Reporting

}REPORTS

Standard protocol0 2 3 4 5 6 7 81

}Math problems

REPORTS

Delayed onset0 2 3 4 5 6 7 81

Insights Without InsightInsights Without Insight

"I felt like I was sort of sliding downhill again. And, um ... there were instructions and a person and uh, I don't know." (JAV, rpt 6)

"I was having a rather vivid image as though I was moving forward through some kind of a forest... I was moving forward very stiffly. Um, my entire upper body was incredibly straight ... it felt almost as if I was moving forward on a conveyor belt, and, without my legs actually moving." (MAM, rpt 8)

"I felt as though I was falling downhill. And I was dreaming about like instructions to a young king or something." (JAV, rpt 4)

The Biology of InsightThe Biology of Insight

The discovery of “insights” is aided by:

• Shutting down logical (DLPFC) processing• Shutting down episodic memory replay (HC)• Enhancing error detection (ACC, MOFC)• Enhancing weak associations, and thereby …• Enhancing the recognition of accommodations

that expand our understanding of the world

The Biology of InsightThe Biology of Insight

All of which occurs during REM Sleep!

Thus sleep, and REM sleep in particular, may not only represent a model system for the processes involved in insight …

But may actually represent a brain state which evolved, in part, to facilitate the discovery of insights.