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The Body Clock Guide to Better Health: How to Use your Body's Natural Clock to Fight Illness and Achieve Maximum Health


A medical breakthrough explained by the leading authority on the connection between health and your body clock.

Chronotherapy — adjusting the care of the body to coincide with the body's natural clock — is poised to be the next major revolution in medical science. An understanding and awareness of these rhythms will enable us to maximize the effects not only of medications and other treatments but also of diets, exercise programs, and other ...

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A medical breakthrough explained by the leading authority on the connection between health and your body clock.

Chronotherapy — adjusting the care of the body to coincide with the body's natural clock — is poised to be the next major revolution in medical science. An understanding and awareness of these rhythms will enable us to maximize the effects not only of medications and other treatments but also of diets, exercise programs, and other daily routines.

The Body Clock Guide to Better Health combines a detailed discussion of major issues, such as sleep, exercise, and nutrition, with a comprehensive A-to-Z reference to specific disorders. Among the health concerns it addresses are AIDS, arthritis, asthma, ADD, cancer, depression, diabetes, digestive problems, allergies, heart disease, chronic pain, sexual dysfunction, and complications from pregnancy. General chapters explore the big picture — including monthly cycles and life cycles — and provide invaluable advice on foods and dietary supplements, fitness, better sex, jet lag, and more.

The Body Clock Guide to Better Health offers readers the dual benefits of improving the treatment of specific conditions while boosting their overall health and wellness.

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Editorial Reviews

From the Publisher
"This book summarizes for the first time for the general public the most important findings on biological rhythms and health . . ." —Erhard Haus, M.D., Ph.D., Director of Pathology, Regions Hospital; President of American Association for Medical Chronobiology
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Product Details

  • ISBN-13: 9780805056624
  • Publisher: Holt, Henry & Company, Inc.
  • Publication date: 1/1/2001
  • Edition description: First Edition
  • Edition number: 1
  • Pages: 448
  • Sales rank: 1,449,305
  • Product dimensions: 6.00 (w) x 9.00 (h) x 1.00 (d)

Meet the Author

Michael Smolensky, Ph.D., is acknowledged as one of the leading authorities in this revolutionary new field. He directs the Hermann Hospital Chronobiology Center at the University of Texas at Houston.

Lynne Lamberg is a medical journalist and editor, with several books and dozens of national magazine articles to her credit. She lives in Baltimore, Maryland.

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Read an Excerpt

It's about TIME

In 1996 the American Medical Association (AMA) asked the Gallup Organization to see if the nation's physicians and the general public knew that symptoms of many common illnesses worsen at predictable times of day or night, and improve at other times. When do heart attacks and asthma attacks occur most often? When are stuffiness, runny nose, sneezing, and other allergy and hay fever symptoms worst? When is blood pressure highest?

* Most physicians got every answer wrong.

* The typical adult flunked, too.

* Even persons with the target illnesses lacked vital facts that could improve their health, and possibly save their lives.

* Both doctors and patients wanted more information about how time of day affects illness and well-being.

This book addresses that quest for knowledge. It starts with this claim: Most of us don't know how to tell time. Body time.

We pay more attention to watches we wear on our wrists than to clocks we acquire in the womb.

A wristwatch tells only one kind of time: world time. You must heed world time if you are getting married in the morning, have to catch a train, or want to see the six o'clock news. But no wristwatch tells when you think fastest, add numbers best, or swing a tennis racquet most deftly. A glance at your watch might make you think "time to eat," or "time for bed," even if your stomach isn't rumbling, or you haven't started to yawn. Feeling hungry or sleepy, however, requires a watchful brain, a brain with its own clock. A biological clock. A hard-wired program that ties your daily behavior to the rhythms of our planet and runs in the background of your life, adjusting automatically, as circumstances demand.

Most of us think we run our lives by the world's clock. Indeed, we often protest that this clock runs us, griping, as did Shakespeare's King Richard III, "time is wasting me." Life in the fast track both seduces and enslaves us. At work, we churn out faxes and E-mail, sometimes even to the person in the office next door. We've revved up our pace to Internet Time, fretting at the few seconds' delay signaled by the icon on our computer screens depicting the now obsolete hourglass.

Who has time to visit with friends? To read the books and magazines piled on the nightstand? Where do we find so-called quality time for our partners or children? Some 47 million Americans now work at paid jobs on weekends.

Recognition that nighttime is the right time for sleep has faded with the availability of hundreds of television channels at any hour, and the ease of ordering pizza around the clock even in small towns. If we can't fall asleep or stay asleep, or can't get going in the morning, we grumble about bad sleep, but the real problem may be bad timing. Most people don't know they can fix this broken clock themselves.

While we drive, we gulp coffee, gobble fast-food meals, and gab on the phone. Some cars now boast fax machines. Cats nip the heels of dogs as Americans' favored pets; cats don't need to be walked. A New York woman earns her living as a personal shopper. She picks out clothes for her busy clients ... from catalogs. We're under the sway of what Stephen Bertman, author of Hyperculture, calls "the power of now." We mimic the March hare, constantly complaining, "I'm late. I'm late, for a very important date."

The brain's clock governs whether or not you're crabby before you have your morning coffee, how quickly you can write a letter and how accurately you can proofread it, how long it takes you to bike ten miles, whether or not you fall asleep at the symphony, when your ulcers act up, and more. Like the crocodile in Peter Pan, we carry this clock around inside of us. Many of us don't hear it tick.

Sara Discovers Her Body Clock

Sara liked to bound out of bed in the morning, pull on her jogging clothes, and go for an easy run. When her knees and back started hurting, she added ten minutes of warm-ups and cool-downs. The pain, unfortunately, did not go away. To give herself more time to stretch, she put off running until she came home from work. Happily, her pain disappeared. What's more, Sara could run faster and farther. She certainly enjoyed her exercise more.

A specialist in chronobiology, the science of body time, could tell Sara why. Peak performance in most sports occurs in late afternoon and early evening, when body temperature reaches its daily high. Respect for this body rhythm may decrease your likelihood of injuries, whether you're a neighborhood jogger or an elite athlete. Training and competition times may influence who wins Olympic games and other high-powered sporting events. Stanford University scientists found that players' biological rhythms predicted winners of Monday Night Football games better than the Las Vegas point spread did.

If Sara wants to maintain or lose weight, or become a partner in her law firm, tuning into her body rhythms can help her achieve those goals more effectively. If she develops a cold, suffers from hay fever, or becomes pregnant, body rhythms will move to center stage in her life.

These findings represent a major leap in scientific understanding: a new way to maintain and optimize health, and to prevent and treat illness. Known as chronomedicine, it holds implications for vastly improving all of our lives.

What Chronomedicine Means to You

Chronomedicine can help you cope better with short-lasting illnesses such as colds and flu, episodic ones such as headaches and back pain, and persistent ailments such as arthritis, high blood pressure, heart disease, cancer, and more. This book details important recent advances to help you in your everyday life.

We report evidence from studies at leading medical centers worldwide showing that:

* Many illnesses disrupt normal body rhythms. Upsets in the body's most dominant rhythm, the daily wake/sleep cycle, provide an important clue to alert you that something is wrong. Complaints about fatigue and poor sleep trigger visits to the doctor for diseases as diverse as AIDS, diabetes, depression, and multiple sclerosis.

* The signs and symptoms of many illnesses vary across the twenty-four-hour day, over the month, and around the year. Some disorders peak in the morning; heart attacks, strokes, cluster headaches, hay fever, and rheumatoid arthritis are some examples. Others flare at night, including asthma, gout, colic in infants, gastric ulcers, and heartburn. Most chronic illnesses in women worsen in the days just before a menstrual period. Over the year, premenopausal women are most likely to discover a cancerous lump in a breast in the springtime, and men to find a testicular cancer in the winter.

* Time of day patterns help identify causes of many illnesses. Bringing symptom patterns to your doctor's attention may help your doctor figure out what's wrong faster and more accurately. The predictable morning spurt in blood pressure and clotting of red blood cells, for instance, make heart attacks and strokes peak in the morning, too. Disruptions in the flow of oxygen to the brain in sleep may produce morning headaches.

Chronotherapy, or timed treatment, aims to correct these underlying causes or reduce their adverse impact. Knowing symptoms' time of origin may enable your doctor to use more precise and effective treatment.

itches in the body clock itself may undermine health, making you fall asleep too late, wake up too early, or suffer blue moods. Chronotherapy offers new ways to reset your body clock and resolve such problems.

The time of day you take diagnostic tests or undergo medical procedures alters the results. If you have asthma, for example, your airway function will vary over the day. It probably is best in mid-afternoon, and poorest in the early morning. If you routinely go for a checkup in the afternoon, your doctor may think your treatment is working fine. But if you routinely go for a checkup first thing in the morning, the severity of your illness will be more apparent.

* Time-of-day norms are known for many rhythms. In the majority of the population, persons who stay awake in the daytime and sleep at night, who follow fairly regular schedules, the ups and downs of most daily rhythms prove quite predictable from day to day. Some labs already report findings with a time-of-day correction factor. New ambulatory monitoring devices can show your doctor how your blood pressure, heart rate, activity/rest cycle, and other indicators of your health change around the clock. Computer programs can analyze the data, making its collection and assessment practical.

* The time you take medicine matters. Taking the right medicine at the right time for your body and your illness may boost the medicine's efficacy and cut its unwanted side effects. The upshot is that you probably will feel better, be more willing to continue taking the medicine, need to see the doctor less often for symptom flare-ups or adverse drug reactions, and need fewer hospitalizations for chronic illnesses.

* Nondrug treatments may help correct underlying disturbances in the body clock. Exposure to sunlight-equivalent light, as one example, is now held to be the treatment of choice for persons with winter depression. Light exposure also benefits elderly persons who sleep poorly and wander at night, as well as shift workers and jet-lagged travelers.

* How you organize your daily life, with respect to sleep, meals, exercise, and other factors may make symptoms better or worse, and hasten or slow your recovery. If you have insomnia but stick to a regular wake-up time seven days a week, however bad the night, for instance, you'll probably sleep better in the long run than if you succumb to the impulse to sleep in.

How This Book Can Help You

We will show you

* the time of day, month, and year that symptoms flare in asthma, arthritis, diabetes, headaches, and many other common diseases

* how to observe and chart your personal symptom patterns by using do-it-yourself tests and diaries

* which times are best for many medical tests and procedures

* When to take your medicine to ensure that it works best and causes the fewest unwanted side effects

* how to monitor your own treatment

* Which times are best for different types of exercise

* how to instill good sleep habits in young children, why not to hassle your teenagers when they sleep late on weekends, and how to get a good night's sleep yourself

* how to reach and maintain your ideal body weight

* What time of day is best for intercourse if you want to conceive

* how to prevent or minimize jet lag

* how to cope with working outside the traditional 9 to 5 hours

This information has never before been gathered in one place for both doctors and the general public. This book aims to be the first comprehensive guide to chronomedicine and chronotherapy.

What Doctors Don't Know about Health and Body Time

Chronomedicine is a brand-new concept, not only to the average person but also to most doctors. More than half of the 320 primary care physicians surveyed in 1996 for the American Medical Association said they were not familiar with chronobiology. One in four asserted that biological rhythms are not important in diagnosis or treatment.

Most of the doctors — even those who claimed to know something about chronobiology — did not know that some common illnesses predictably flare in the morning, afternoon, evening, or night, or they picked the wrong time. They did not know that blood pressure varies significantly over the day or that labor pains spontaneously start most often at night. They thought that diagnostic tests give the same results whenever they are performed, and that medications and other treatments work equally well, and are equally likely to cause unwanted side effects whenever they are given. They were wrong. We will show you why.

These were experienced physicians in their peak professional years. Most were under age fifty and had been practicing general family medicine or internal medicine for ten years or more. Nearly all saw 400 patients or more each month, persons with all of the illnesses or conditions included in the survey. Yet they knew only slightly more than their patients about the time patterns for high blood pressure, arthritis, respiratory allergies, asthma, chest pain, heart attacks, and migraine headaches.

Only one out of three physicians, most under age forty, said they had learned about chronobiology in medical school. Most of those who had at least some familiarity with the topic said they had gotten their information from reading medical journals. In 1996, the year of the survey, about two thousand articles on chronobiology were published in the world's scientific journals, far more than any one doctor was likely to read, but perhaps still not a critical mass.

Doctors and their patients also learned about chronobiology from news media reports. In recent years, The New York Times, The Washington Post, The Wall Street Journal, Time, Newsweek, and many other leading newspapers and magazines have reported advances in chronobiology. All of the television networks have produced stories on such topics as timed treatment for cancer and other illnesses, drowsy driving, the genetics of the biological clock, sleepy teenagers, jet lag's impact on athletes, melatonin, light therapy, and more.

Such stories still may be too infrequent, or too diverse and seeming unconnected, to reshape attitudes and behavior. Among the general public, even persons who had the illness in question rarely recognized the predictability of its time course.

* Now that you mention it, I do often wake up with a migraine.

* My hay fever is worse in the morning.

* My osteoarthritis acts up in late afternoon. Guess I try to do too much early in the day.

* I just got to work when wham! The pain hit me. It's lucky I wasn't driving when I had my heart attack that morning.

Same Dose of Medicine Sometimes "Too Much" or "Too Little"

Think how often a doctor has handed you a prescription, saying, "Take this medicine three times a day." By linking pill-taking to mealtimes, the doctor knows you'll be more likely to remember to take your medicine. A "four times a day" prescription adds bedtime to the list. This approach is obsolete.

In prescribing equal doses over the day, your doctor presumes that your need for medication is the same all day, and that a consistent amount of medication confers a uniform benefit at all times. This belief is wrong.

If your symptoms wax and wane over the day, you need proportionately more medication to control them at some times, and less at others. Moreover, the way your body absorbs, uses, and excretes drugs varies over the day. The same dose of medicine may be too much at one time, and too little at another. Medicine that may help you at one time may not work as well at another. It may not even work at all. At some times, it may even be harmful.

Consider aspirin, the staple of the family medicine cabinet and one of the world's most widely used medications. Aspirin has a high safety record, particularly when taken in relatively small doses now and then. The problems come mainly with prolonged use, since aspirin may irritate the lining of the stomach and cause stomach ulcers and bleeding. These effects may occur even with the "baby aspirin" dosage (75 to 100 milligrams) that millions of Americans, particularly those in their forties and older, take once a day to prevent a heart attack or stroke. Taking aspirin at the proper time dramatically lowers your risk of developing stomach irritation and injury. Aspirin is least likely to cause irritation if you take it at night, and most likely to do so if you take it in the morning. Some persons who cannot tolerate aspirin when they take it in the morning have little or no difficulty when they take it at night. (See page 209.)

Asthma attacks are one hundred times more frequent at night than in the day. Persons with severe unstable asthma who live on a conventional awake-in-the-daytime, asleep-at-night schedule get the most relief and greatest protection at night by taking their tablet steroid medication around 3 p.m. If you are a night worker, your doctor will need to synchronize treatment time with your schedule. (See page 220.)

Most medications used to ease peptic ulcers work best when taken once a day, around 6 p.m., with dinner. Taken at this time, they help block the normal late-night peak in daily secretion of stomach acid. (See page 323.)

In cancer, cells are most vulnerable to damage when they are dividing. Anticancer medications attack different stages of the cell reproduction rhythm. Some, such as 5-fluorouracil, which is used to treat cancers of the intestinal tract, are best tolerated and cause the fewest side effects when given by infusion while the patient sleeps at night. Others, including adriamycin and doxorubicin, which are used to treat bladder, ovarian, and other cancers, are best tolerated when given in the morning. When cancer medications are given in a chronobiological manner, that is, according to body rhythms, patients may be able to tolerate higher, more potent doses than would be possible otherwise. (See page 229.)

Monthly Rhythms May Alter Symptoms, Too

In the AMA's 1996 survey, only three out of four doctors agreed that the menstrual cycle is a biological rhythm. All doctors should know this is true. Women know it: most recognize that their weight, energy, mood, sleep, cravings for particular foods, interest in sex, skin eruptions, frequency of migraines, asthma attacks, and symptoms of other illnesses predictably wax and wane over the month. Numerous factors, including stress, work, sleep, diet, and even the weather, may make some months more troublesome than others. Some women suffer more intensely than others, a reason some physicians and even some women dismiss or trivialize these symptoms.

Being tuned into these rhythms, however, can afford women a hardy measure of equanimity. A woman who is watching her weight may feel less guilty about nibbling a brownie right before her period starts. For many women, this is "the chocolate time of month," a few days with increased craving for chocolates and other sweets. A female athlete or actor may tolerate slight slips in performance, if she knows it's normal to be less coordinated, less "together," when she's menstruating.

Many women don't know that a routine test for cervical cancer, the Pap smear, gives the most accurate results if performed near ovulation. A woman can boost her odds of having this cancer detected at its earliest, most curable stage simply by scheduling this exam midway between her periods. (See chapter 11: "Time for Sex.")

Many chronic illnesses flare around the time of menstruation. Consider asthma: three out of four adults admitted to the hospital for treatment of life-threatening asthma attacks are female. Their hospital admissions occur four times more often just before or after menstruation than at any other time of month. Knowing that this is a more vulnerable time should heighten women's attention to their symptoms, and prompt physicians to fine-tune treatment. That won't happen until both patients and doctors focus their attention on body clocks. (See chapter 15: "Sickness and Health from A to [nearly] Z.")

The time of month also may influence the success of treatment. Fifteen studies involving more than 5,000 women with breast cancer show that those whose surgery is performed in the early part of the later half of their menstrual cycle live longer on average than women who undergo surgery earlier or later in the month. But many cancer experts still are skeptical about these findings, and most operations for breast cancer are scheduled according to the surgeon's convenience. (See page 233.)

Ancient Cultures Recognized Body Time

"Of themselves, diseases come among men, some by day and some by night" the Greek poet Hesiod wrote in 700 B.C. "Whoever wishes to pursue the science of medicine in a direct manner," the great Greek physician Hippocrates observed three hundred years later, "must first investigate the seasons of the year and what occurs in them." Yet generations of physicians have paid little heed.

Nei Ching, the classic Chinese medical text written in 300 B.C., set forth the notion of health as a balance of opposites: cold and warm, moist and dry, passive and active. Yin and Yang, moon and sun, night and day, wife and husband, together represent the whole universe. Yin/Yang remains a central concept in Chinese medicine. It is represented pictorially by a circle that shows the moon and sun embracing. The American Academy of Sleep Medicine, the sleep field's leading professional organization, uses this symbol to signify its goal of optimizing both sleep and wakefulness.

Monuments built by ancient civilizations reflect knowledge of body time as well as planetary time. Shadows cast by the sun on the towering slabs at Stonehenge constructed in southwestern England some 4,000 years ago show changes in day length over the year. One circle at Stonehenge holds the correct number of markings to calculate the length of a woman's menstrual cycle or the likelihood of pregnancy, chronobiologist Sue Binkley reports.

Twenty-four baboons carved into the face of a cliff at Abu Simbel 3,200 years ago guard the entrance to a temple to Pharaoh Ramses II. The baboons represent the twenty-four hours of the day, a way of dividing up time the ancient Egyptians devised some 400 years earlier. The baboons symbolize the Pharaoh's round-the-clock rule, gaining this honor by dint of the Egyptians' belief that they urinated once an hour: an overstatement, researchers who specialize in baboon behavior today say.

The words of Ecclesiastes remind us that our ancestors took rhythmic behavior for granted: "To every thing there is a season, and a time to every purpose under the heaven." The list includes "a time to be born, and a time to die," as well as "a time to heal."

Even the notion of body clocks is not brand new. The English writer Robert Burton observed, in the seventeenth century, "Our body is like a clock; if one wheel be amiss, all the rest are disordered, the whole fabric suffers: with such admirable art and harmony is a man composed."

Early in the twentieth century, most physicians in the United States attended to all sorts of ills. When called in the late evening, they could predict their patient might have a flare of a peptic ulcer. If roused closer to dawn, they could anticipate seeing a patient with an asthma attack or a woman about to give birth. The morning brought heart attacks. Today, a person with stomach ulcers might see a gastroenterologist; one having trouble breathing, an allergist or lung specialist; and one with chest pain, a cardiologist. Births more often are induced, typically at the convenience of mother and doctor, and in the daytime. Only the sickest patients go to hospitals, where activity around the clock blurs the distinction between night and day. The present-day lack of appreciation for body time thus is a relatively recent phenomenon. The rise of specialization in medicine has eroded physicians' recognition of the ubiquity and significance of daily rhythms for health and disease.

The history of medicine is studded with facts that were known, lost, and later rediscovered. Body rhythms are "hot" again today. Some formidable hurdles, however, still stand in the way of their widespread acceptance.

Copyright © 2000 Michael Smolensky, Ph.D., and Lynne Lamberg

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Table of Contents

1 It's about TIME 3
What Chronomedicine Means to You 5
How This Book Can Help You 7
What Doctors Don't Know about Health and Body Time 7
What Do You Know about Health and Body Time? 8
Same Dose of Medicine Sometimes "Too Much" or "Too Little" 9
Monthly Rhythms May Alter Symptoms, Too 10
Ancient Cultures Recognized Body Time 11
2 Your Body Is a Time Machine 13
Constancy Is an Illusion 13
Constancy and Change Coexist in the Body 16
A Half-Century of Studies Shows That Body Time Matters 17
Most Drug Testing Ignores Time of Day 18
New Drug Design Exploits Body Rhythms 20
Chronomedicine Fosters Research on Gender 21
Chronomedicine: It's Not a "Some Day" Science 22
3 The Discovery of Inner Clocks 23
Science Prompts "The Buzz" 24
No Sun Worshipers Here 25
Cinderella Has a Message for You 26
Seminal Discovery Set Off No Fireworks 28
4 How Your Body Clock Works 30
How Your Brain's Brain Does Its Job 30
The Search for Master Clock Spanned Decades 31
A Rare Hamster Opens New Doors 32
Light Signals Set the Clock 32
Why You Need a Night-Light 33
Melatonin Is the Hormone of Darkness, Not of Sleep 36
The Time Melatonin Is Taken Governs Its Impact 36
Be a Scientist: Study Your Own Body Rhythms 37
5 Are You a Lark, an Owl, or a Hummingbird? 40
What Type of Bird Are You? 40
Punch Your Own Time Clock 47
Can Larks and Owls Happily Share a Nest? 50
Lark/Owl Traits Affect Family Life 52
Are Larks Healthier and Wealthier? 53
6 Your Mind at Work 56
Science Yields New Spin on "Best Times" 56
Effort Determines Mental Performance 58
Testing Is Tricky 59
Memory Skills Change over the Day 59
Don't Let the Post-Lunch Dip Get You Down 61
Moods Change over the Day 62
7 A Good Night's Sleep 66
How Much Sleep Do People Need? 67
Sleepless in Seattle, New York, and Your Town, Too 68
Learn How to Unlock Your Personal Sleep "Gates" 70
What Happens When We Sleep? 70
Put Your Internal Alarm Clock to Work 72
How Do People Cope with Extreme Sleep Loss? 74
Why We Must Sleep 75
Timewise Tips for Good Sleep 77
8 The Growing Years 80
Babies 80
Ages One Through Six 83
Ages Seven Through Twelve 84
Ages Thirteen to Nineteen 85
Teenagers Lead Busy Lives 86
More Sleep Brings Better Grades 87
Minnesota Starts Classes Later, Launches Study 88
Timewise Tips for Teenagers 90
Timewise Tips for Parents 90
9 Fitness by the Clock 92
Media Coverage Sets Competition Times 93
What Times Are Best for Sports Performance? 94
Menstrual Cycle May Alter Sports Performance 97
Home Field Advantage Includes "Home Time" Advantage 98
Jet Lag Undermines Sports Performance 100
Does Exercise Help or Harm Sleep? 101
Is It Okay to Exercise near Bedtime? 102
Exercise May Help Troubled Sleepers Most 103
Timewise Tips If You Have a Chronic Illness 104
What's the Best Time for Gym Class? 105
10 Time to Eat 106
When We Eat 106
Three Meals a Day by Nature's Design 106
Regular Mealtimes Increase with Age 107
Fasting in Ramadan Alters Many Daily Rhythms 108
Regular Meals May Keep Other Rhythms in Line 109
What We Eat 110
Breakfast: Energy 110
Lunch: Sustained Alertness 111
Dinner: Relaxation 111
Bedtime Snack 111
How Much We Eat 112
Americans Eat Too Much and Exercise Too Little 113
How Our Bodies Handle Food 114
To Lose Weight, Eat Breakfast 114
Snacking Does Not Spoil Your Appetite 115
How Foods Affect Mind and Mood 116
Caffeine Is a Stimulant 116
Alcohol Is a Depressant 117
Sugar Has Short-Lived Effects 118
Is There a Best Time to Take Vitamins and Minerals? 118
11 Time for Sex 121
Sexuality 121
Best Time of Day 121
Most Popular Day of the Week 122
Preferred Time of Month 122
Most Active Time of Year 123
Menstrual Cycle 123
The Typical Menstrual Cycle Has Its Own Rhythms 124
Light Exposure May Regularize Cycles 128
Why Close Friends Often Menstruate at the Same Time 129
Pregnancy 131
Timewise Tip If You Want to Get Pregnant 131
Can You Choose to Have a Boy or Girl? 132
Pregnancy Disrupts Sleep 132
Timewise Tips to Improve Sleep If You Are Pregnant 133
Nighttime Is Prime Time for Births 133
Perimenopause and Menopause 134
What Causes Hot Flashes? 135
Drop in Estrogen Affects Many Bodily Functions 135
Timewise Tips for Menopausal Women 137
Hormone Rhythms in Men 138
Male Midlife Changes 139
What Treatment Is Available? 140
Erectile Dysfunction Now out of the Closet 140
Timewise Tips for Men with Erectile Dysfunction 141
12 Getting the Jump on Jet Lag 143
Jet Lag Is a Modern Malady 144
Daytime Symptoms Bother Travelers Most 145
Travel Fatigue Makes Jet Lag Worse 146
Culture Shock Doesn't Cause Jet Lag 147
Flying East Is Harder than Flying West 147
North-South Flights Don't Cause Jet Lag 148
Why You Sleep Poorly 150
When Can Sleeping Pills Help? 151
We All March to Different Drummers 151
Bright Light May Speed Clock Resetting 152
Can Melatonin Prevent Jet Lag? 156
Does the Jet Lag Diet Work? 158
Plan Your Visit to the Timeful Hotel 159
13 Clockwatching at Work 164
Out-of-Date Schedules Foster Driver Fatigue 165
Poor Schedules Blamed for Major Industrial Catastrophes 166
One in Five Americans Works Evenings or Nights 168
Types of Schedules Vary Widely 169
Why Shift Workers Rarely Adapt 170
How Out-of-Kilter Clocks Harm Workers' Health 171
Sleep and Digestive Problems Bother Shift Workers Most 172
Female Shift Workers Face Added Health Problems 180
Does Shift Work Shorten Your Life? 182
Some Chrono "Types" Manage Shift Work Better 182
Forward Rotations Easier on Body 184
Best Speed of Rotation Still Debated 184
Bright Light May Speed Clock Resetting 185
Can Melatonin Help Shift Workers? 187
Lawsuits May Force Workplace Changes 188
Timewise Tips for Employers 189
Timewise Tips for Employees 190
14 A Time to Heal 193
Keep Your Own Chronorecord 193
Educate Your Doctor 194
You Need the Right Medicine at the Right Time 197
Best Time to Take Most Medicines Not Known 198
Finding Best Time Proves Daunting Task 198
Some Chronotherapies Are Already Available 199
15 Sickness and Health from A to (Nearly) Z 201
Aids 201
Fatigue Dampens Quality of Life 202
Sleep Disturbances Occur Early in HIV-Infection 203
HIV-Infection Changes Immune and Hormone Rhythms 204
More Research Needed on Medication Timing 205
Arthritis 206
Osteoarthritis (OA) 207
Take Your Medicine before Pain Usually Starts 207
Timewise Tips for OA 210
Rheumatoid Arthritis (RA) 210
Take Medicine at Night to Prevent Morning Pain 211
Timewise Tips for RA 213
Asthma 214
Asthma Has Many Triggers 215
Why Asthma Peaks at Night 216
Physicians Still in the Dark on Nighttime Pattern 217
Attacks Vary over Menstrual Cycle 218
Attacks Vary by Season 218
Better Results, Fewer Side Effects with Timed Dosing 218
Back Pain 223
Back Pain: A Glitch in Human Design 224
Osteoarthritis Causes Most Back Pain 224
Morning Back Pain Linked with Rare Condition 224
Take Your Medicine before Pain Usually Starts 225
Cancer 226
Cancer Cells Multiply Too Fast 227
Anticancer Drugs Kill Both Cancer Cells and Normal Cells 227
How Timed Medication Dosing Works 229
Rhythms Affect Breast Cancer Detection 232
Does the Time of Breast Cancer Surgery Affect Survival? 233
Does the Time of Radiation Therapy Make a Difference? 235
Colds and Flu 236
Cause of Colds No Mystery 237
Medications Can Ease Cold Symptoms 237
Medications Can Ease Flu Symptoms 239
Try to Get Your Flu Shot in the Morning 240
Colic 241
Constipation 242
Bowel Activity Is Cyclic 243
What Causes Constipation? 243
Get More Fiber, More Fluids, Eat Regular Meals 244
Diabetes 245
What Goes Wrong in Diabetes? 246
Daily Rhythms Alter Blood Sugar Control 246
Menstrual Cycle Affects Diabetes 247
Diabetes May Be Harder to Manage in Winter 247
Timed Dosing of Insulin Improves Control of Type I Diabetes 247
Diet, Exercise, Drugs Improve Type II Diabetes 248
Epilepsy 250
What Goes Wrong in Epilepsy? 250
Sex Hormones Alter Epilepsy in Women 251
Sex Hormones May Alter Epilepsy in Men, Too 253
Sleep Laboratory Studies Aid Diagnosis and Treatment 253
Time of Dosing May Alter Efficacy of Antiepilepsy Drugs 254
Fibromyalgia 255
Body Clocks May Be out of Sync in FM 256
Gallbladder Attacks 258
Gout 258
Growing Pains 259
Hay Fever 260
What Causes Hay Fever? 260
Why Are Symptoms Worst in the Morning? 262
T-i-m-e Spells Relief 263
Headaches 265
Migraines 266
Menstrual Migraines 268
Cluster Headaches 268
Tension Headaches 269
Sex and Headaches 270
The Exploding Head Syndrome 270
Timing May Be Tip-off to Diagnosis 271
Old and New Medications Ease Headaches 271
Timewise Tips for Women with Migraines 272
Timewise Tips If You Have Cluster Headaches 274
Heartburn 274
Take Medication in the Evening for Nighttime Symptoms 275
Heart Disease 276
Heart Attacks Peak in Morning 277
What Makes Mornings Risky? 277
Angina (Chest Pain) Peaks in Morning 278
Heart Attacks Jump on Mondays 279
Heart Attacks Surge in Winter 280
Is Morning Exercise Safe? 280
When Is Sex Safest? 281
Chronotherapy Can Help Prevent Heart Disease 281
Chronotherapy Can Help Treat Heart Disease 283
High Blood Pressure 285
How Blood Pressure Works 285
3 in 10 Americans with High Blood Pressure Don't Know It 286
Causes of High BP Still Unknown 286
What the Numbers Mean 286
How Time of Day Alters BP 287
Monthly and Yearly Rhythms May Alter BP 288
Discover Your Daily Cycle 288
Daily BP Patterns Predict Health Risks 291
Chrono Success Stories: Preventing Blindness, Helping Babies 292
Medications for High BP: What Time Is Best? 293
Using Chronobiology to Design Better Drugs 294
Mood Disorders 296
Seasonal Affective Disorder 297
Bulimia Nervosa 301
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