The Scientific American Day in the Life of Your Brain: A 24 hour Journal of What's Happening in Your Brain as you Sleep, Dream, Wake Up, Eat, Work, Play, Fight, Love, Worry, Compete, Hope, Make Important Decisions, Age and Change

Acknowledgments xiii

Preface xv

Introduction 1

You Gotta Know the Territory: A Short Tour of Your Brain 4

Your Neurotransmitters 6

Charting the Day: Your Body Clocks 8

The Best of Times? 9

COMING TO CONSCIOUSNESS Awake and Aware 5 A.M. TO 8 A.M. 13

5:00 a.m. Waking to the World 14

Your Inner Alarm Clocks 14

Your Brain Chemicals 15

Larks and Owls 16

Coming to Our Senses 19

An Orchestra of Sensory Harmony 20

Touch and Movement: Feeling Our Way 22

Varieties of Touch 23

6:00 a.m. Coming to Consciousness 25

The Seat of Consciousness 26

Emotion, Memory, and Consciousness 27

It’s Always About Networking 28

Little Gray Cells and Big White Matter: Myelin in Your Brain 29

Prime Time for Heart Attack and Stroke 31

7:00 a.m. Those Morning Emotions 33

Reason Needs a Neurochemical Boost 34

Can Meditation Help Master Those Emotions? 36

Is There a God Spot in Your Brain? 37

Practice Makes Compassion 39

8:00 a.m. Finding Your Way 41

Why His Brain May Not Ask Directions 42

How We Know Where to Find Our Lost Keys 44

ENGAGING THE WORLD Getting Out and About 9 A.M. TO NOON 47

9:00 a.m. Encountering Others 48

That Face, That Familiar Face 48

Friend or Foe? Read My Face 49

Mirror, Mirror: Copycat Neurons in the Brain 51

The Broken Mirror: Autism Insights from Mirror Neurons and Face Perception 52

10:00 a.m. Peak Performance—or Stress? 55

Stress in the Brain 55

The Alarm That Doesn’t Stop: Why Chronic Stress Is So Bad 56

Stress Destroys Neurons 56

Stress Ups the Risk of Alzheimer’s Disease 57

The Very Thought of It Is Enough 58

Multitasking—Again? 59

The Limits of Multitasking 60

How Your Brain Helps Your Job Kill You 61

You Can Lull Your Brain Away from Stress 62

Flow Versus Stress 63

11:00 a.m. Decisions, Decisions, and More Decisions 65

The Brain’s CEO 65

“Chemo Brain” Can Ambush Your CEO 66

Choosing Economically 67

Making an Emotional Moral Choice 68

Choosing Wearies Your Brain 69

The Brain Has a Section for Regret 70

Noon The Hungry Brain 72

How Hunger Works in Your Brain 72

We’re Losing Our Scents 73

Still Hungry? When Hunger Goes Awry 74

Why Calories Taste Delicious 75

Addicted to (Fill in the Blank) 76

Self-Control Sucks Your Energy 78

Yes, There Is Such a Thing as Brain Food 79

THE GUTS OF THE DAY Getting Down to Business 1 P.M. TO 4 P.M. 83

1:00 p.m. The Tired Brain 84

Partial Recall: Why Memory Fades with Age 84

Can You Help Your Brain Stay Young(er)? 85

Predicting Alzheimer’s Disease 86

How Forgetting Is Good for the Brain 86

Asleep at the Wheel—Almost? It Could Be Narcolepsy 88

1:54 p.m. Just Time for a Six-Minute Power Nap 89

2:00 p.m. Bored Bored Bored 90

Can’t Get No Satisfaction? Maybe It’s ADHD 90

ADHD and Risk Taking Could Be Good—Sometimes 92

Wired and Hooked: Addicted to Technology 93

3:00 p.m. Your Pain Is Mainly in the Brain 95

How Pain Hurts Your Brain 96

Mind Under Matter, Mind over Brain 96

Is Hypnosis Real? 98

A Window into Traumatic Forgetting 100

4:00 p.m. Exercise Your Brain 102

Exercise Grows Neurons and Improves Memory 102

Why We Get Food Cravings 104

The Most Dangerous Time for Teens 105

The Teen Brain Is Still Changing 105

But Don’t Forget Hormones 106

TIME OUT Letting Go and Coming Home 5 P.M. TO 8 P.M. 109

5:00 p.m. The Dimming of the Day 110

Is It Really Depression? Or Just a Bad Patch? 110

Searching for the Pathway to Depression 111

Maybe You’re Just SAD 112

Magnetic Energy May Work When Meds Fail 113

A Peak Time for Suicide 113

Good Grief: Addicted to Grieving 114

6:00 p.m. Coming Home 116

An Oxytocin High 116

Nobody Home? Loneliness Hurts 117

Oh, Those Comforting Cravings. Or Is It Addiction? 119

Bottoms Up: Where Many Alcoholics End 120

Is Addiction the Result Rather Than the Cause of Brain Damage? 121

Still Crazy After All These Years? Aging Isn’t Stopping Drug Use 122

7:00 p.m. Gotta Sing, Gotta Dance 124

The Musical Path to the Brain 125

Music Survives Brain Damage 125

Your Brain Expands to Store Music 127

So You Think You Can Dance? 128

Born to Rock 128

The Creative Brain 129

Right Brain, Left Brain? 130

Don’t Oversimplify That Right Brain Stuff 131

The Musical Ear Is Learned, Not Born 132

8:00 p.m. Humor Is Healthy 133

The Best Medicine 133

Tracking Your Internal Laugh Track 134

TV Addiction Is No Mere Metaphor 135

WINDING DOWN Fear, Sex, Sleep, and Dreams 9 P.M. TO MIDNIGHT 139

9:00 p.m. Things That Go Bump in the Night 140

How Fear Works in Your Brain 140

Who’s Afraid? Not These Brain Cells 141

When the Brain Decides It’s Time to Scram 142

The Many Parts of a Violent Brain 144

10:00 p.m. Lust, Sex, and Love 147

Your Brain on Sex 147

Women, Men, and Orgasms: How Alike Are They? 150

Does the Penis Have a Brain of Its Own? 151

What’s Love Got to Do with It? Plenty, It Turns Out—for Women 153

Are You Born Gay? Sexual Orientation Is Biology, Not Choice 154

11:00 p.m. Falling Asleep 156

The Five Stages of Sleep 156

Insomnia: Curse of the Night 159

Perhaps Less Is More? 160

Interrupted Sleep? Don’t Call It Insomnia. It’s Normal 161

Call Me Sleepless 162

Still Awake? Can You Catch Up on Lost Sleep? 163

Is Insomnia Worse for Night Owls? 164

Midnight Sleeping in the Midnight Hour 165

Strolling in Your Sleep 165

Drifting into Dreamland 166

Do Banished Thoughts Resurface in Dreams? 169

Want to Dream More? Try Sleep Deprivation 169

NIGHT CREW AT WORK 1 A.M. TO 4 A.M. 173

1:00 a.m. Night Crew at Work 174

Cleaning Up Your Neural Garbage 175

Why Your Brain Doesn’t Take a Break Already 176

The 10 Percent Myth 178

2:00 a.m. Going Against the Clock in Your Brain 179

Disasters on the Night Shift 180

Lack of Sleep Aff ects Doctors as Much as Alcohol 181

Less Sleep? More Fat 181

Biorhythm and Blues: Faulty Clocks 183

Resetting Your Body Clock 183

3:00 a.m. Awake and Anxious 185

Where the Nightmare Begins 185

A False Alarm 186

That Pill to Fix Your Ills Has a Price 188

3:30 a.m. Night Nurse on Duty 189

4:00 a.m. Last Sleep 191

4:30 a.m. Awake So Early? You May Be an Unlucky Lark 192

Your Brain Tomorrow 193

Sources 195

Illustration Credits 213

Glossary 215

About the Author 223

Index 225