Jet Lag and the Business Traveler—Mood, Behavior and Work Functioning - April 27, 2000

Mark Rosekind, Ph D, Alertness Solutions

DR. JARRIS: Dr. Rosekind is going to speak on Jet Lag and the Business Traveler, Mood, Behavior and Work Functioning, and then Dr. Björn Lemmer is going to speak on time zone travel and peak performance.

I will introduce the speakers individually. We will have approximately 30 minutes of presentation per speaker and then reserve 30 minutes for questions.

Dr. Rosekind is the President and Chief Scientist of Alertness Solutions. He is internationally recognized for translating scientific knowledge on sleep, circadian factors, human fatigue, performance and alertness into practical strategies that improve safety and productivity in our 24-hour society.

He has published numerous journal articles on sleep performance and mood. He has also led the Fatigue Countermeasures Program at the NASA Ames Research Center and developed alertness programs for several companies, including British Airways, whom we heard from earlier.

Dr. Rosekind will give a presentation on the disruption of sleep and the internal circadian clock. The presentation will highlight physiologic sleep need, accumulating a sleep debt, recovery sleep, circadian rhythms and patterns and disruptions and effects on performance alertness and mood.

Dr. Rosekind.

DR. ROSEKIND: Thank you.

They always put the fatigue, fall asleep lecture right after lunch, right?

I am going to talk about the physiological challenges associated with travel. And I am going to start by giving us a perspective. Just think about how travel has changed over the years. This is a picture of Charles Lindbergh and it has been over 70 years since his historic transoceanic flight.

A lot of people don't realize that he was actually awake for 24 hours before his flight across the Atlantic for 33-1/2 hours. He was awake for 24 hours, flew for 33-1/2 hours, which means that he had been awake for 57-1/2 hours when he landed in Paris.

Consider how much the technology associated with travel has changed so dramatically and evolved just over the last 70 years since Lindbergh. However, think about all of us as humans that haven't changed at all, which is the context really of what I have to present. While things have advanced technologically, global demand, 24 and 7, the physiology and how we are designed as humans hasn't changed at all. And there is a dramatic challenge for us now trying to operate 24 and 7 crossing time zones.

And just to demonstrate that jet lag and fatigue have been issues around for a long time, this is something that Lindbergh wrote about his trip. "My mind clicks on and off; I'm trying to let one eyelid close at a time while I prop the other open with my will. My whole body argues dully, that nothing life can attain is quite so desirable as sleep. My mind is losing resolution and control."

Of course, the technology continues to evolve. In fact, you think you experience jet lag, astronauts are going around the earth every 90 minutes. So, their day/night cycle is 90 minutes long.

The challenges related to managing jet lag, are only going to become greater. The demand is not going down. The demand is increasing. Airplanes will be built that will fly further and faster with more people. And so technology will continue to evolve, just consider what travel will look like in five or ten years from now.

Now what is the issue here? Time zone crossings, long days, night flying, alternating day/night schedules, changing schedules, all of these come together into what is known as jet lag. We can use the word "fatigue", sometimes "jet lag", in the same way that we talk about stress. It is a summary descriptor of a lot of different symptoms.

And what are the causes of those symptoms and signs of jet lag and travel fatigue? Well, there are actually a wide range of factors that can exacerbate or create jet lag or the fatigue associated with it. And while there is a whole list of them, I am going to focus on two primary physiological ones: sleep and the internal body clock or the circadian clock.

In fact, what is interesting is that while there is a lack of data regarding psychosocial factors related to travel, in the physiological realm there are thousands of papers regarding sleep, the circadian clock and the physiological processes associated with how those change with travel.

Most people think when your head hits the pillow, you fall asleep, departed from the world around you. Sleep is actually a very dynamic, physiological state divided into two distinct states.

Many people have heard of REM [ph] or rapid-eye- movement sleep, the time when you dream. The other kind of sleep, non-REM (NREM) sleep, non-rapid-eye-movement sleep. Non-REM sleep is divided into four stages, one, two, three, and four, with stages three and four the deepest sleep. If I were to wake you up in your bed in the deepest non-REM stages three and four sleep, I would come in and wake you up or I would call your name "Leonard, wake up", it could take two or three minutes for Leonard to finally wake up. When I do wake him up, I say tell me what were you dreaming about and you would have very little recall of any mental activity.

If awakened in that deep non-REM three and four sleep, individuals can experience sleep inertia, which is a prolonged sleepiness and grogginess associated with waking up out of deep sleep.

Though a gross over-simplification, non-REM sleep is particularly involved in physical restoration during the night. While our physiology slows down in NREM sleep, in REM sleep it is extremely active. Your brain is as active as when you are awake. The brain is active, though you are paralyzed while dreaming.

When you are dreaming, your brain is actually thinking about doing whatever it is you are dreaming about but the brakes are on in the brain stem. REM sleep is most involved in mental restoration during the night.

And every night when your head hits the pillow, this is what the nightly NREM/REM pattern looks like. Most of the deep sleep we get, that physical restoration time, occurs in the first third of the night. If you take a nap that is too long, say about an hour, where does that put you? Right in the middle of that first NREM stages three and four of the night.

Also, notice that the REM periods become more regular and occur longer later in the night. REM periods later in the night are more intensive, physiologically and psychologically.

DR. ROSEKIND: How much of this physiological sleep do you need, not do you get, but how much do you need? Physiologically, we know that people need about eight hours. There is a bell curve, however, and so there is a range from about six to ten hours of individual sleep need.

Therefore, for everyone in the room who thinks they are a six-hour sleeper, there is a ten-hour sleeper in the room as well.

The average physiological need for us is eight hours. If you don't get that needed sleep, it doesn't just disappear. You accumulate what is called a sleep debt. And here I am finally at the World Bank and the IMF talking about this.

Think about this just like your bank account. You need eight hours; but you only get six. Well, you are now two hours in the red. Then you only get six hours the second night; now you are four hours in the red.

And so, even if you sleep a little bit more but still under what you need, you are still going to accumulate a sleep debt. So, literally, everything below the eight sleep need is going to create more debt.

The average, at least in the United States, is that most people get from one to one-and-a-half hours less sleep than they actually, physiologically need. In a regular work week of five days, it means by the weekend you are seven-and-a-half hours in the red. It is literally as if you had stayed up one full night.

In 1995, there was a National Commission looking at this and Bill Dement, the Chair, would say that our U.S. sleep debt is greater than our economic debt. So, my company did a calculation and figured out that, at least in the United States, we are looking at about 105 billion hours of sleep debt. In this 1995 Commission report on sleep disorders, they estimated in the U.S. alone we probably pay about $130 billion associated with sleep disorders, lost productivity, absences on the job, etc.

A study that just came out shows that in the U.S., we pay about $14 billion per year just for insomnia, in terms of office visits, medications, nursing homes, and related costs.

Roughly, there is a 2.3 trillion global sleep debt.

How does this pertain to you? There is a great study that was done by American Express that shows, on average, people traveling are getting an average of about six hours of sleep. All of these people are therefore likely to be carrying a significant sleep debt.

The most dramatic changes in sleep occur as a normal function of aging. There are three significant factors that change as you approach about age 50 or older.

One, your sleep becomes less deep. NREM stages three and four almost disappear. Two, your sleep becomes more fragmented, so there are more awakenings throughout the night. And third, your brain does not consolidate sleep at night as well.

Some people interpret that to mean that individuals need less sleep as they get older. No; we know that napping and day-time sleepiness increases if you don't get sufficient, consolidated sleep at night.

As our physiology changes, the strategies you used when you were younger that allowed you to cope and manage jet lag and travel, may not be as effective as you get older because your physiology is changing.

Age is a significant factor that affects sleep. But there are two others that I want to mention as well. One is alcohol. Alcohol is a major REM suppressant. What does that mean? More than a couple of glasses of wine, a couple of beers or one or two good shots of hard liquor, and you will suppress the REM sleep in the first half of the night.

Sufficient alcohol will create what is called a REM rebound and all of that suppressed REM in the first half of the night comes back in higher amounts during the second half of the night. Now, what is the number one sleep aid used in the United States? Alcohol.

Therefore, if you are not careful, alcohol intended to promote sleep can actually worsen your sleep. People can wake up and have more disturbed sleep.

A third factor that can disturb sleep are sleep disorders. In any given year, we know about a third of the adult population will complain about a sleep problem. Some, new data suggests that this prevalence may be even higher, possibly two-thirds of the adult population. This is for all types of complaints about sleep.

There are a wide range of causes. There is a nosolgy that characterizes 82 different categories of sleep disorders, ranging from psychological to sleep apnea.

There are many people who are misdiagnosed or not identified as having a sleep disorder. Why do I mention this? Let's talk about one example, sleep apnea.

Studies have shown that people with sleep apnea have a two to seven times increased risk for car accidents, and a study just published this fall found that people with mild to moderate apnea can have a performance level equal to 0.5 to 0.8 blood alcohol levels.

So, you take somebody who doesn't know they have apnea, who already has a performance decrement, and then have them cross a lot of time zones, change their schedules, etc., and this will exacerbate their fatigue and sleepiness. Another important factor is that there is a significant discrepancy between what people report about their alertness and sleepiness and their physiological state.

This slide is from a NASA study some years ago, a JAL (Japan Airlines) scientist, and what you see at the top is a one to seven scale called the Stanford Sleepiness Scale; the ratings range from one, wide awake and alert; to four, you are sort of medium or okay; to seven, your head is about to hit the table, you are about to fall asleep.

This scale can be used to rate subjectively how you feel. This slide shows data from a pilot. At that peak where he rates himself as a one, he is reporting himself as most alert.

At the bottom of the slide is a physiological measure of alertness. It is a gold standard for objectively and physiologically measuring sleepiness. And it is really simple. The operational definition of sleepiness is that the faster you fall asleep, the sleepier you are.

So, you put an individual in a dark room, wire them up and measure how fast they fall asleep. It is a 20-minute test and is done multiple times during the day.

And, as you would expect, if you are wide awake the whole time, then you get a score of 20. If all of you are kept awake for 24 hours, or you had sleep apnea, you would fall asleep in five minutes or less every time we did this test. That is called the twilight zone. Physiologically, if you stay awake for a prolonged period, you will fall asleep on an average of three minutes.

Here is an individual reporting that he is at a rating of one (wide awake and alert), but physiologically he is about to enter the twilight zone. Ask somebody who is already tired "how they are doing", and their tendency will be to say "I am fine". So, reflect on the data we saw this morning, where all the travelers said they are doing just fine, jet lag is not a big deal, and 100 percent of the spouses and the partners said they are all exhausted, they are miserable, they are irritable at home. That is the discrepancy between self-report and physiological state that we are talking about.

And so, just asking somebody "are you alert, okay to do your job" is not the method to obtain a reliable estimate.

Now, let's focus for a few minutes on the circadian clock and then close examining the costs are associated with the issue of fatigue. There is a circadian clock in the brain, located in the suprachiasmatic nucleus (SCN) of the hypothalamus. This clock particularly controls internal physiological rhythms on a 24-hour basis.

In the old days, we described the clock as actually running close to about 25 hours, at 24.9 hours. In fact, this is old news as of this past summer. A great study out of Harvard by Charles Czeisler and colleagues, has demonstrated that the human circadian clock runs at about 24 hours, 11 minutes, which is closer to plants and other species in which work has been done.

This slide gives you a sense of all the different internal physiological functions that are controlled by the circadian clock. You are biologically programmed so that every 24 hours you sleep alternating with a period of wakefulness.

So, let's take that clock and cross time zones, and show how the laboratory data translates to the real world and how complicated it gets.

The data on this slide are from a NASA study examining long-haul pilots that slept in laboratories for 48 hours during their layover.

What you see on the left, the black bars, are where they go to bed and get up on a regular basis at home, a very regular pattern. Portrayed on the right is when this group was traveling in an eastward direction, and you see the sleep periods are all over the place. Short sleep, long sleep, long periods of wakefulness, the sleep/wake pattern is all over the place.

This next slide shows you the sleep/wake pattern for the same group of pilots when they have flown in a westward direction. A much more regular pattern of sleep/wakefulness. So, even the direction that you fly can affect the quantity and quality of sleep that you obtain.

When people start acknowledging that jet lag and fatigue are issues, then very often they are literally asking for the magic bullet to fix the situation. However, as you can see, even something as straightforward as the direction you fly in can make a difference. And while it might be an advantage flying one way, you then pay the price coming home.

There are two times during the day that physiologically we are programmed to be sleepy. The one where we are most significantly sleepy is from 3:00 to 5:00 a.m. That is the trough of the circadian clock. That is when we are the most sleepy; our temperatures are at the lowest, our performance is at the lowest, etc.

There is another sleepiness dip to a lesser degree during siesta time in the afternoon. Everyone typically believes that we get sleepy after lunch because of a big lunch we ate. But, whether you eat or not, you will get sleepy in the afternoon because you are biologically programmed. Now if you have a big lunch, you may get sleepier faster, but you are going to get sleepy whether you eat or not in the afternoon.

There are also two periods of wakefulness during the day, about twelve hours apart. When you have stayed up all night and in the morning the sun comes up and then all of a sudden, you begin to feel better again. That is an effect of circadian clock, acting as an alarm clock, waking you up. That second wind in the morning that you get is part of the circadian pattern.

One common misconception is that you get to a local destination, and all those internal rhythms, such as hormones, sleep/wake, temperature, readjust in a few days.

However, many of those internal rhythms actually readjust at different rates. It can actually take two to three weeks, depending on the rhythm, for all of the internal adjustment to take place.

So, people may say they feel great in a day or two at a new destination but if we were to actually measure hormones, temperature, etc, physiologically they would still be internally or externally out of sync. Any timezone change over three hours, requires a reasonable amount of readjustment.

Disrupting the circadian clock and sleep, are associated with well-established costs. Bottom line, every aspect of human capability can be degraded with sleep loss and circadian disruption. For example, judgment and decision-making can be decreased by 50 percent. Memory can be reduced by 20 percent.

Mood can be reduced by 100 percent. Good mood goes down; bad mood goes up, whatever the emotional scales you want to use. So again, think about the data we heard this morning about what happens in relationships, at work, etc. In many ways, though people don't make the attribution, the physiological disruption that I have described literally sets the foundation for a lot of the other factors and effects that were described this morning.

This last slide is for all of the frequent travelers who think that if they reduce their sleep, they will get more accomplished. This is part of the 24 and 7 myth. If I am awake longer, I will get more done.

This is a study was conducted by Greg Belenky and colleagues at the Walter Reed Army Institute for Research here in D.C. They did a great study looking at productivity and the effects of cumulative sleep loss.

They had a productivity measure, and examined subjects getting only seven hours, six hours, five hours or four hours of sleep, of course, the idea being that the more you are awake, the more subjects would be productive.

Here is what subject's productivity looked like at seven hours of sleep per day. Here they are six, five and four hours of sleep. So, the strategy of getting less sleep to be more productive actually works for one day. What you see is that getting four, five and six hours, there is higher productivity for one day, the lines cross at Day 2.

We are just starting to hone from the laboratory to what the real world costs are in this area. And there is a lot of work that needs to be done to further quantify the costs associated with fatigue, sleep loss, and circadian disruption.

The physiological disruption associated with travel is present, whether it is acknowledged or not. The costs are there whether you want to acknowledge them or not. The good news is that there is so much scientific data available to address the issue; it is your call whether you choose to act and do something about it or not.

Thank you.

[APPLAUSE]

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