Why We Sleep

✦

UNLOCKING THE POWER OF SLEEP AND DREAMS

✦

Matthew Walker, PhD

2

Figure 1: Typical Twenty-Four-Hour Circadian Rhythm(Core Body Temperature)

Time (Twenty-Four Hours)

Rect

al T

empe

ratu

re (°

C)

37.2

37.1

37.0

36.9

36.8

36.7

36.6

12 pm 4 pm 8 pm 12 am 4 am 8 am

WhyWeSleep_TO_1_circadian.pdf 1 5/11/17 10:27 AM

TimeNoon Noon6 am6 pm Midnight

Figure 2: The Cycle of Melatonin

Mel

aton

in (p

g/m

L pl

asm

a)

50

40

30

20

10

0

WhyWeSleep_TO_2_melatonin.pdf 1 5/11/17 10:29 AM

Figure 3: E�ects of Various Drugs on Spider Web Building

Normal LSD

Marijuana

Speed

Ca�eine

WhyWeSleep_TO_3_effects.pdf 1 3/16/17 10:40 AM

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Figure 4: The Two Factors Regulating Sleep and Wakefulness

Sleep reduces adenosine(Decreasing sleep pressure, or Process-S)

Process-S(Sleep drive)

Process-CCircadian

(Wake drive)7 am 11 pm

sleep sleep7 am 7 am11 pm

WhyWeSleep_TO_4_twofactors.pdf 1 5/11/17 10:30 AM

Figure 5: The Urge to Be Awake

Strong urge to be awake(Small distance between Process-C and Process-S)

Process-S(Sleep drive)

Process-CCircadian

(Wake drive)7 am 11 pm

sleep sleep7 am 7 am11 pm

WhyWeSleep_TO_5_urge.pdf 1 5/11/17 10:31 AM

Figure 6: The Urge to Sleep

Greatest urge to sleep(Greatest distance between Process-C and Process-S)

Process-S(Sleep drive)

Process-CCircadian

(Wake drive)7 am 11 pm

sleep sleep7 am 7 am11 pm

WhyWeSleep_TO_6_urgetosleep.pdf 1 5/11/17 10:31 AM

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Figure 7: The Ebb and Flow of Sleep Deprivation

Overpowering urge to sleep

Weak urge to sleep

Strong urge to sleep

Process-S(Sleep drive)

Process-CCircadian

(Wake drive)7 am 11 pm

awake awake sleep7 am 7 am11 pm

WhyWeSleep_TO_7_ebbandflow.pdf 1 5/11/17 10:32 AM

11 pm Midnight

Wake

REM

NREM Stage 1

NREM Stage 2

NREM Stages 3 and 4(Slow wave sleep)

1 am 2 am 3 am 4 am 5 am 6 am 7 am

Figure 8: The Architecture of Sleep

Cycle 1 Cycle 2 Cycle 3

Time of Night

Cycle 4 Cycle 5

WhyWeSleep_TO_8_architecture.pdf 1 3/16/17 10:48 AM

Figure 9: The Brainwaves of Wake and Sleep

Awake

Deep NREM sleep

REM sleep

50µV

1 s

WhyWeSleep_TO_9_brainwaves.pdf 1 3/16/17 10:49 AM

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Figure 10: Sleep Loss and Sports Injury

Average Sleep

% C

hanc

e of

Inju

ry

8070605040302010

06hr 7hr 8hr 9hr

WhyWeSleep_TO_10_sportsinjury.pdf 1 3/14/17 10:46 AM

Figure 11: NBA Player PerformanceMore than Eight Hours Sleep vs. Less than Eight Hours Sleep

+12% Increase in minutes played

+29% Increase in points/minute

+2% Increase in three-point percentage

+9% Increase in free-throw percentage

+37% Increase in turnovers

+45% Increase in fouls committed

WhyWeSleep_TO_11_nba.pdf 1 6/15/17 1:00 PM

Figure 12: Sleep Loss and Car Crashes

Increase Crash Risk

Hou

rs o

f Sle

ep

<4 Hr

4–5 Hr

5–6 Hr

6–7 Hr

x2 x4 x6 x8 x10 x12

11.5

4.3

1.9

1.3

WhyWeSleep_TO_12_car.pdf 1 3/16/17 10:51 AM

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Figure 13: Sleep Loss and Obesity

Date (Year)

Aver

age

Slee

p Am

ount

Obese Individuals (US)

10 hr

9 hr

8 hr

7 hr

6 hr

35%

30%

25%

20%

15%

10%1940 1960 1980 2000

WhyWeSleep_TO_13_obesity.pdf 1 3/14/17 11:26 AM

Figure 14: Example of a Memory Association Network

UC Berkeley

Berkeley Courses Sports

California Quake Graduate Academe Football

Sun Tsunami Job Knowledge Stanford

Beach Ocean Money Advance Rivalry

WhyWeSleep_TO_14_memory.pdf 1 3/16/17 8:55 AM

Figure 15: Risk of Death from Sleeping Pills

Sleeping Pills Used/Year

Odd

s Ris

k of

Dea

th

6X

5X

4X

3X

2X

(baseline) 1X

NONE ½–18 18–132 >132

WhyWeSleep_TO_15_sleepingpills.pdf 1 6/15/17 1:03 PM

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Figure 16: Global Economic Cost of Sleep Loss

Nation

Billi

ons (

US $

)

(A) $450

$375

$300

$225

$150

$75

$0US UK Canada Japan Germany

$411

$40$21

$138

$60

NationGD

P

(B) 3.5%

3.0%

2.5%

2.0%

1.5%

1.0%

0.5%

0.0%US UK Canada Japan Germany

2.3%

1.9%

1.4%

2.9%

1.6%

WhyWeSleep_TO_16_globalecon.pdf 1 3/16/17 8:24 AM

Figure 17: Levels of Sleep Intervention

Societal

Public Policy/Government

Educational/Interpersonal

Organizational

Individual

WhyWeSleep_TO_17_intervention.pdf 1 3/16/17 9:11 AM