Chat Transcript: Author Lynne Lamberg Discusses The Body Clock

Is there a right time to take your medicine? To conceive a child? Why do some people gain weight during the winter months? Are you more productive at work in the daytime, or in the afternoon? According to the authors of a new book about chronomedicine, timing IS everything.

The Body Clock Guide to Better Health examines how determining the optimum time for an individual to eat, sleep or work can improve his or her overall well-being.

Lynne Lamberg, co-author of The Body Clock Guide to Better Health, joined us today in an online chat.

Moderator at 11:55pm ET

Welcome, Lynne Lamberg.

Theresa M from at 11:56am ET

Do body clocks change radically as we age?

Lynne Lamberg at 11:58am ET

Body clocks do change dramatically from early in life to late in life. Even when babies are only two days old, they know the difference between day and night — they predictably sleep longer at night. A dramatic change in the body clock occurs in the teenage years. Teenagers are programmed to go to sleep later, and to sleep later in the morning. That's why many high schools in the United States are starting to change their hours to a later time.

As people get older, they become more apt to go to bed earlier, and to wake up earlier. Some seniors have problems in that they go to bed much too early in the evening to enjoy a normal social life, and they wake up at three or four in the morning, while the rest of their household is still asleep.

Moderator at 11:59am ET

How can people who work long hours and have erratic schedules adjust their body clocks?

Lynne Lamberg at 12:00pm ET

That's a big problem in our society. Many of us don't pay much attention to regular bed times and regular wake-up times. As a result, body rhythms are often markedly disrupted. People who work in the evenings or at night often have trouble sleeping in the daytime because humans are programmed for daytime activity and nighttime sleep. It's not possible to easily go to sleep whenever we want to. We have to respect the body clock.

People can best cope with the demands of the body clock by trying to stick to a regular wake-up time seven days a week, regardless of when they go to sleep. That's the most important thing you can do to keep body rhythms in line.

Isaac from at 12:02pm ET

Dear Lynne,

I normally take a walk in the morning and evening. Are these the best times for exercise? PS: Loved the book — pawed through it a couple of times.


Lynne Lamberg at 12:04pm ET

The best time to exercise is whenever it is convenient. However, the body is really designed to exercise most easily in the late afternoon. This is the time when muscles are most flexible and joints move most easily. Most people find that they can exercise the best at that time, and most major sporting achievements have been accomplished in the late afternoon or in the evening.

MarkusDamon from at 12:05pm ET

How much hard evidence (statistically significant) is there to support the claims made in your book?

Lynne Lamberg at 12:06pm ET

The book includes more than 700 scientific references, and we read thousands more. In the past 20 years there's been a dramatic upsurge in studies of the biologic clock, and all of the studies we report in the book are evidence-based.

But most doctors still don't know this information. A Gallup survey, conducted for the American Medical Association, that asked doctors and the general public when symptoms of many common illnesses occurred found that most doctors got every answer wrong. Medical schools still aren't teaching doctors much about the biologic clock. But as new evidence accumulates, it will get into the medical curriculum.

We hope The Body Clock Guide to Better Health will give readers the information they need to work with their doctors to improve their own health.

Jimmy at 12:08pm ET

Is daylight savings time good or bad for us?

Lynne Lamberg at 12:09pm ET

Although the daylight savings time change is only one hour, it has a surprisingly big impact on the body — more than travelling across one time zone in a plane. That's because when we stay home, we're just pretending that the sun rises and sets at a different time, and our bodies depend on sunlight to organize body rhythms.

After the spring daylight savings time change, most people get a little less sleep than usual, feel more cranky, and traffic crashes go up. After the fall change, people get a little more sleep, and moods improve.

Dan Persica at 12:11pm ET

Is there any truth to the myth that teenagers need more sleep than younger children and adults?

Lynne Lamberg at 12:13pm ET

Absolutely. Studies in a summer sleep camp that started in the 1970s show that teenagers need, on average, nine hours and 20 minutes of sleep a night. Few of them get this much, because most high schools start too early. Some high schools in this country start before seven o'clock, but the average teenager feels most comfortable going to sleep after 11 o'clock p.m..

As a result, teenagers don't get the sleep they need to be fully alert in class. Some studies show that teenagers who get more sleep get better grades, are less apt to use drugs, and have fewer driving mishaps. The state of Minnesota has been in the vanguard of moving school start times later. They have found that SAT scores rose in high schools that start later, and teachers, students and parents all think the late start times are a great idea.

Moderator at 12:13pm ET

Are companies paying more attention to the body clocks of employees?

Lynne Lamberg at 12:15pm ET

Some are. There is a move to raise awareness of body clock issues in the work place. There are many things that 'round-the-clock work places could do to help workers cope better with shift work. It would be to their advantage to do so, because better schedules promote higher employee morale, higher productivity, and lower job turnover.

Among the things companies could do is to adopt schedules that rotate forward around the clock, which is easier on the body. Companies could educate workers about body clocks — especially about sleep, diet and exercise. Another thing that a few enlightened companies are doing is allowing napping in the work place, providing nap rooms to be used on breaks. Naps at the job help prevent napping on the job.

There are things that employees also can do to make shift work easier, especially if they work at night. One is to do your most boring tasks early, and your most interesting ones toward the end of the shift. Another is to plan what and when you eat. Many people who work at night snack a lot, and as a result they often gain weight.

Another tip is to minimize use of coffee when working at night. And it's a good idea to protect daytime sleep by making your room as dark and quiet as possible. In The Body Clock Guide, we offer a long list of tips for both employers and employees on how to ease adaptation to shift work.

Patty at 12:20pm ET

Is metabolism related to how much sleep an adult needs? I'm 31 and still needing as much sleep as a teenager would.

Lynne Lamberg at 12:21pm ET

Everyone has different sleep needs. There is no one-size-fits-all formula. The average adult probably needs about eight hours of sleep, but most of us get less than that. In fact, most American adults get about six hours and 40 minutes of sleep, on average.

Patty, if you are getting eight or nine hours of sleep a night and you feel fully rested and alert in the daytime, that's great. You're listening to your body clock and doing what's best for you. Most people don't pay enough attention to how much sleep they need to feel fully rested all day long.

Cari at 12:22pm ET

What about finding the best time to conceive? Is there any relationship between a healthy pregnancy and timing?

Lynne Lamberg at 12:24pm ET

Yes, there is. The right time to conceive runs from about five days just before ovulation through the day of ovulation. Intercourse even one day after ovulation is unlikely to result in pregnancy. There's also a best time of day. It seems that sperm travels more rapidly in the afternoon, so couples who are trying to conceive might keep that in mind.

It's now possible to determine the date of ovulation quite reliably. Inexpensive home urine tests are available in most pharmacies. They work by measuring monthly shifts in hormone levels.

Rick at 12:25pm ET

I've been working a night-shift schedule consisting of 13 hours a night, three nights a week, for the last six years. I do get four days off to recover. On my days off I shift back to a normal sleeping schedule. My work leaves me physically and mentally exhausted. Do you have any suggestions for optimizing my sleeping and eating schedule?

Lynne Lamberg at 12:27pm ET

Rick, this is the biggest problem that shift workers face — on their days off, they revert back to the awake-in-the-daytime, asleep-at-night schedule that is traditional in our society. Ideally, a person who works shifts would try to stay on the same schedule seven days a week. Of course, if you work at night, that means that on your days off you would still be sleeping in the daytime, which probably would interfere with family and social life.

One tactic that may help is to try to get as much sleep as you can in the same time slot every day, regardless of the shift that you are on. And work hard to ensure that you can get as much sleep as possible. This might mean disconnecting the telephone, taping the doorbell, and adopting other tactics to keep people from bothering you. But sleep is really important, and getting enough of it is probably the only way to avoid feeling exhausted.

Moderator at 12:31pm ET

How would an intense workout schedule affect your body clock?

Lynne Lamberg at 12:32pm ET

A regular exercise schedule, like regular times for sleep and regular mealtimes, helps keep body rhythms in line. All of these activities help program the body to expect the same activities at the same time the next day, and to prepare for them by secreting the proper hormones, raising blood pressure or heart rate — whatever is necessary — and making it easy to do the specific activity.

Whether the exercise is moderate or intense shouldn't make a difference, the issue is if it's regular. People often worry about whether exercise in the evening will disturb their sleep. Even some sleep experts advise people not to exercise within three hours of bedtime.

However, as we report in The Body Clock Guide, new research shows that if people are comfortable exercising right before bed, there's no reason to avoid it. Some people say it helps them relax and fall asleep easily. If that's true for you, then late night is a good time to exercise.

Moderator at 12:35pm ET

Do you attribute the rising number of cases of diseases like chronic fatigue syndrome to people ignoring their body clock?

Lynne Lamberg at 12:36pm ET

I can't speak specifically to chronic fatigue syndrome, but there are many illnesses where the body clock is quite important, in terms of symptoms. Some of these are fatiguing illnesses, like fibromyalgia, multiple sclerosis, or AIDS.

In many other illnesses, symptoms wax and wane across the day. Take asthma, for instance. Asthma attacks occur 100 more times more often between four a.m. and six a.m. than at other hours of the day. That's because airways are most constricted in these hours in everyone, not only persons with asthma.

This is a daily rhythm. Airways are most relaxed around 3 p.m.. In fact, that's one of the reasons that exercise is easiest in the late afternoon. If you are healthy, your airway function varies only a little from day to night, and you won't be aware of the difference. But if you have asthma, your best to worst airway function may vary from day to night by 50 to 60 percent. The more variation you have, the more severe your asthma probably is.

This is especially a problem for women, because asthma attacks vary over the menstrual cycle. About one in three women with asthma finds her symptoms increase right before or while she has her period. Three out of four adults who require hospital treatment for severe asthma attacks are women, and most hospitalizations in menstrual-age women occur in the days just before or after their period starts.

Other illnesses, including fibromyalgia, multiple sclerosis and epilepsy also vary over the menstrual cycle, with symptoms often worsening just before a woman's period starts.

In The Body Clock Guide we include a menstrual diary, a pain diary, a fatigue diary, and other diaries readers can use to chart their own particular symptom pattern. These diaries are useful to take to the doctor to discuss treatment.

Yuri Kuechle at 12:45pm ET

You say that people are programmed to sleep during the night. How then can you explain why there are those of us who function best at 12 and one a.m.? What about us night owls?

Lynne Lamberg at 12:47pm ET

I understand that completely — I'm a night owl myself. About one in 10 persons is an extreme lark, or morning person, and about two in 10 are owls, who enjoy staying up long past midnight. The rest of us are somewhere in the middle. But as we argue in The Body Clock Guide, everyone needs to figure out his or her own best time, and to try to adapt their life to their own natural rhythm as well as possible.

Luckily for night owls, there are plenty of jobs available in today's world because of the Internet and the global economy. The biggest problem for night owls is trying to conform to a nine-to-five world. It really helps if they can find a way to adapt their work and daily life to their natural tendencies.

Being a lark or an owl is not a choice, it's built in to our genes, and it helps to understand your own proclivity. In the book, we include a lark/owl test that helps people figure out their own daily pattern. One simple question is, what's your favorite meal? Extreme larks love breakfast, but night owls typically say their favorite meal is dinner.

Couples who are considering marriage need to examine their partners' and their own tendencies to be a morning person or a night person in the same way they consider questions about religion and jobs. Couples where both persons are matched — either both owls or both larks — generally rate their marriages as more satisfactory than those who are not well matched. However, couples who are not well matched but also work at it can also have a great relationship.

Moderator at 12:53pm ET

Lynne, do you have any final thoughts to share?

Lynne Lamberg at 12:55pm ET

I'd just like to urge people to particularly pay attention to the times that symptoms of illnesses occur, and to talk with their doctor about whether the times they take medicine might improve their symptoms.

In The Body Clock Guide to Better Health we survey more than three dozen illnesses — many that we didn't have time to talk about today, including hay fever, headaches, heart disease, skin disorders, sudden infant death syndrome, and others. There's lots of information there that we hope readers can use to live healthier, happier lives.

We have a Web site,, where we've posted the table of contents and an excerpt from the book.

Moderator at 12:55pm ET

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