Understanding jet lag

Jet lag is a circadian rhythm sleep-wake disorder. It occurs when rapid travel across multiple time zones disrupts our internal body clock. Our circadian rhythms, synchronized by cues such as daylight and darkness, regulate our sleep-wake cycle, ensuring we feel alert during the day and sleepy at night. However, when we quickly travel across time zones, this synchronization is thrown off balance, leading to symptoms like daytime sleepiness, nighttime insomnia, fatigue and cognitive impairment.

The more time zones you cross, the more severe your symptoms may be. Adjusting to a new time zone tends to be harder when you travel east than when you travel west. It is estimated that it takes one day per time zone that you cross for your body to adjust to the local time.

While jet lag can affect anyone, pilots, flight attendants, and frequent business travelers often experience jet lag more frequently due to their extensive travel schedules. Some data suggest jet lag symptoms may be more severe and may last longer in older people.

Emerging evidence even suggests that jet lag can precipitate mood disturbances, with more depressive episodes after westward travel and manic episodes after eastward travel.

Strategies for reducing jet lag symptoms

Fortunately, several strategies can help minimize the impact of jet lag. Talk to a sleep doctor to determine if any of these options are right for you:

1. Keep your home schedule: Sticking to your regular sleep-wake schedule, particularly for brief trips, can help reduce jet lag symptoms by allowing your body to maintain its accustomed rhythm.
2. Use bright light:  Bright light is an important cue that can affect the timing of your circadian rhythms. For example, exposure to bright light in the morning may help advance your sleep-wake schedule before you travel east. Conversely, inappropriately timed exposure to light and darkness during and immediately after travel can increase jet lag symptoms.
3. Adjust your sleep schedule: You can help your body prepare for travel by adjusting your sleep schedule before your trip. For example, you can shift your sleep schedule earlier for a few nights before you travel east. Consider using an app, such as Timeshifter, to help you adjust your sleep schedule when traveling.
4. Take melatonin: Melatonin is a hormone that helps regulate your sleep-wake cycle. Taking melatonin at bedtime for a few nights after your arrival may help you adjust to a new time zone when traveling east. Melatonin may not be helpful when traveling west less than 12 time zones.
5. Consume caffeine: Caffeine may help improve alertness and reduce daytime symptoms of jet lag, but it also can disrupt your sleep at night.

In addition to these strategies, get plenty of sleep during the nights before your trip, avoid alcohol during your flight, maximize exposure to daylight upon arrival, and exercise before and after travel to help manage jet lag.

If you need help preparing for a long trip, talk to the sleep team at an accredited sleep center.

Medical review by Helena Schotland, MD

Related:

• Overcoming jet lag with the help of a computer program
• How technology is helping – and hurting – your sleep

Authored by: Kate Robards

The post The science behind jet lag and tips to combat symptoms appeared first on Sleep Education.

We sat down with one of the study’s authors, Andrew Tubbs, from the University of Arizona College of Medicine – Tucson, to answer some questions.

First, could you give us an overview of what the “Mind after Midnight” hypothesis means?

I think everyone knows that getting good sleep is important for thinking clearly and making good decisions, mostly because we’ve all felt stupid and made bad choices after a bad night of sleep. But the amount of sleep you have is just one part of a bigger puzzle because sleep happens in the context of our circadian rhythms, the 24-hour cycles in which we live our lives. These rhythms are why, even after a bad night of sleep, we can get up and be awake and alert during the day—our brains are organized around being as functional as possible at that time. What’s important is that the opposite is true at night: Our circadian rhythms reduce wakefulness and alertness at night to help us go to sleep. All the “Mind after Midnight” hypothesis proposes is that people are more likely to make bad decisions when they haven’t had enough sleep and they’re awake when their circadian rhythms are telling them to be asleep. For most people, that’s between 2 to 3 AM, hence “Mind after Midnight.”

All the “Mind after Midnight” hypothesis proposes is that people are more likely to make bad decisions when they haven’t had enough sleep and they’re awake when their circadian rhythms are telling them to be asleep.

What would you say is the most surprising finding?

What surprised me was how the risk of dysregulated behaviors was consistently elevated at the same time. We looked at timing of suicide deaths, timing of homicide deaths, sleep/wake timing among folks with suicidal ideation in both community and national samples and kept getting the same answer: 2 to 3 AM. That’s when we started digging through the basic science on what happens to the brain in the middle of the night and pieced together the “Mind after Midnight” hypothesis.

The other surprising thing (or sad thing, depending on your view) is that there is so little data on dangerous behaviors during the middle of the night. We looked at dozens and dozens of studies and found a handful of times that researchers even looked at what people were doing at night. Hopefully, our hypothesis will motivate folks to look at outcomes during the night.

What do your findings mean for our readers?

What we know is that risk of suicide, adjusted for patterns of wakefulness, seems to be over three times higher at night than during the day. We have similar data for homicide deaths and the results so far are the same: more risk at night, less risk during the day. So, at this point, the evidence seems to be stacking up in the same direction. What we don’t quite know is why the risk is higher at night. This is the “hypothesis” part of the “Mind after Midnight” hypothesis because we hypothesize that the increased risk is due to natural circadian changes in the brain colliding with sleep deprivation to disrupt emotion processing, decision-making, and impulse control. That’s why we need more data to be sure.

Regardless of the reason risk is up at night, we’re still confident that it is. Thus, our best tool to mitigate this risk is still to get a good night of sleep, and for folks with sleep disorders like insomnia or sleep apnea, that means getting good, evidence-based treatments like cognitive behavioral therapy or positive airway pressure therapy.

Some people prefer to stay up late and sleep late. How does the “Mind after Midnight” hypothesis take late chronotypes, or “night owls,” into consideration?

Despite the name, the “Mind after Midnight” hypothesis doesn’t actually claim that risk is highest right after midnight for everyone. We think that risk is elevated because of sleep duration and circadian rhythms, so if you’re a night owl and you regularly go to sleep at 1 AM and wake up at 10 AM, your risk zone is probably closer to 6 or 7 AM. Conversely, a morning lark who goes to sleep at 8 PM and wakes up at 4 AM may have a risk zone around 11 PM to 12 AM. It all depends on the individual, on how much sleep you get, and how your circadian rhythms are organized.

Is there anything else you’d like to share?

It is very likely that not everyone experiences the same risk with being awake at night as everyone else. For some people, the risk may be minimal while for others it may be off the charts. This is why this is such an exciting research hypothesis, because it gives us the tools and framework for finding and explaining the differences between people.

Along those lines, I’ve seen comments from folks on Twitter about how being awake at night increases their creativity and inventiveness, and I think this actually fits into our hypothesis quite nicely. We think that one of the big drivers of risk is behavioral disinhibition, such that people say or do things they wouldn’t ordinarily say or do. For someone already suicidal, this could be extremely dangerous. But for someone creative (who isn’t also suicidal), this disinhibition may help them turn off their inner critic and push forward with new and exciting ideas. I just hope they don’t end up also cutting their ear off (like Van Gogh).

To read the full study, click here. To join the conversation about the “Mind after Midnight” hypothesis on Twitter, click here.

Authored by:

Kate Robards

The post The ‘Mind after Midnight’: People more likely to make bad decisions late at night appeared first on Sleep Education.

Support our body clock and daily rhythms

Sleep is controlled by biological, social, and environmental time-keepers. These include the light we are exposed to, time-of-the-day when we eat our meals, exercise, interact with others, and many more. When we stay indoors for a long period of time, we lose many of these cues. This can be challenging for a good night’s sleep and regular daily routines. Here are some strategies to support our daily rhythms:

• Get up around the same time every day. Your get-up time is like an anchor to your day and night. Keeping a consistent get-up time will help other parts of your day fall into a regular routine and help you sleep better the next night.
• Get bright light into your eyes within a few minutes of getting up and seek light during the day. Our brain’s body clock (or circadian pacemaker) is tuned by daily light. Morning bright light, when received by our brain at around the same time every day, is a powerful time signal of our body clock. Bright light has the added benefit of promoting alertness, which is particularly important if you find it difficult to get going in the morning. Try opening curtains and let in direct sunlight; if you don’t have access to natural light, turn on bright indoor lights.
• Make your first social interaction of the day at the same time each morning. When you are in isolation, interacting with others can be difficult. Try to have a phone or video call with friends or family at about the same time each morning. Even a quick “hello” and check-in is useful. The other person will probably appreciate the human contact too!
• Eat meals around the same time each day, especially breakfast. Eating serves as a time-keeper and helps tune our body clock. Eating meals at the same time of the day supports a healthy biological clock, which is important for sleep.
• Exercise around the same time each day and avoid being sedentary for long stretches of time. Exercise indoors can be challenging. Many video streaming sites have nice at-home workouts you can follow.
• Keep daytime and night-time different and separate. Our body clock benefits from keeping day and night clearly distinguished. During daytime, keep living space full of light, and keep active. For instance, organizing, cooking, cleaning, and indoor exercises. In the evening, keep lights dim, and do quieter activities such as watching TV, reading.
• Keep lights dim and block blue light on electronic devices 1 to 2 hours before bedtime. A dark environment can help your body naturally produce melatonin and prepare your body for sleep. Many devices have settings that can be adjusted to reduce blue light, use these settings or reduce screen brightness while winding down before bed.

This article was written by Drs. Bei Bei, Shantha Rajaratnam, and Sean Drummond from Monash University Healthy Sleep Clinic, Turner Institute for Brain and Mental Health, Monash University, Australia, and Dr. Rachel Manber from Sleep Health and Insomnia Program, Stanford University, USA. You may share this information freely with acknowledgement of the source. Contribution to this via Github is welcome. For questions and comments, please contact bei.bei@monash.edu.

Authored by:

Drs. Bei Bei, Shantha Rajaratnam, Sean Drummond, and Rachel Manber

The post Sleep tips during isolation: Supporting the body clock appeared first on Sleep Education.

Sleep physicians see the end of daylight saving time as a possible conflict between your body’s circadian rhythms and the expectations of society.

“The time change is kind of a society imposed jet lag,” said Nathaniel Watson, MD, Co-Director of the HMC Sleep Disorders Center at the University of Washington. “Your circadian rhythms will cause you to want to go to bed earlier and wake up earlier than your external environment,” said Dr. Watson.

The effect of the time change on your body is similar to taking a flight from New York to Chicago, or for that matter, travelling westbound over any single time zone.

Fortunately, your body is fairly well-equipped to deal with this initial adjustment. You may fall asleep earlier and wake up earlier for several days, but your circadian rhythms will eventually adjust to the new schedule. For people with a typical daytime schedule, this won’t conflict with your required wake-up time.

If you work a non-traditional schedule, or have a little extra time in the morning, sleep physicians suggest you can ease yourself into the transition the week before the time change. Go to sleep and wake up 10-15 minutes later each day and you can minimize the effects of the time change on your body.

After the time change, melatonin supplements may also help if your circadian rhythms are out of synch. By taking a small dose several hours before your intended bedtime, you can shift the timing of your sleep.

Exposure to as much sunlight as possible in the morning can help your body synch with the new sleep schedule. If you live in a winter climate or have a schedule that doesn’t allow for morning sunlight, bright light therapy is a sufficient substitute. You can buy a special light box or desk lamp that simulates sunlight and resets your circadian rhythms. Bright light therapy is also helpful for minimizing seasonal affective disorder (SAD) and preventing insomnia.

The “spring forward” poses more of an immediate challenge to your body.

“In the fall, we gain an extra hour of sleep, whereas in the spring, we lose that hour. Being a sleep restricted society, the loss of one more hour of sleep in the spring is harder to accommodate than gaining an hour in the fall”, said Dr. Michael Decker, Endowed Chair of the Byrdine F. Lewis School of Nursing.

Common mistakes can sabotage your sleep during the adjustment period surrounding the fall time change.

“One of the biggest mistakes that people make regarding the time change is staying up later and thinking that they’re going to get an extra hour of sleep,” added Dr. Kohler.

Other pitfalls to avoid are drinking alcohol close to bedtime or consuming caffeine in the afternoon or later. If you feel yourself getting tired midday, try taking a brief 15-20 minute nap. However, lengthy or late naps can throw your sleep timing off.

Not all states or U.S. territories observe daylight saving time. Hawaii, Arizona, Puerto Rico, the Virgin Islands, American Samoa, Guam and the Northern Marianas will skip the “fall back.”

Daylight saving time is a contentious issue in other countries. Russia ended the practice several years ago, but many residents complain of dark mornings. In Japan, which hasn’t experienced a time change in more than 60 years, there are talks of reinstating the practice to save energy.

“I understand why we do the time change, said Dr. Watson, “My hope would be that we do away with it at some point and just allow our internal circadian rhythms to move along naturally with the light dark cycles that change from season to season. But I don’t think that’s going to happen.”

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“We should acknowledge the unforeseen importance of our 24-hour rhythms for health,” said Claudia Coomans, Ph.D., a researcher involved in the work from the Department of Molecular Cell Biology in the Laboratory of Neurophysiology at Leiden University Medical Center in Leiden, Netherlands. “To quote Seneca ‘We should live according to nature (secundum naturam vivere).'”

For the study, Coomans and colleagues exposed mice to constant light, which disturbed their normal internal clock function, and observed a gradual degradation of their bodies’ internal clocks until it reached a level that normally occurs when aging. Eventually the mice lost their 24-hour rhythm in energy metabolism and insulin sensitivity, indicating that relatively mild impairment of clock function had severe metabolic consequences.

A number of sleep disorders that are linked to misaligned circadian rhythms including insomnia, jet lag and shift work disorder Abnormal circadian rhythms have also been blamed for depression, bipolar disorder and seasonal affective disorder, which is more common in the winter.

The American Academy of Sleep Medicine considers sleep disorders an illness that has reached epidemic proportions. Board certified sleep medicine physicians in an AASM accredited sleep center can provide effective treatment. AASM encourages patients to talk to their doctors about sleep problems or visit www.sleepeducation.com for a searchable directory of sleep centers.

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AASM spokesperson Ron Kramer, MD, with Walter Reed National Military Medical Center in Bethesda, Md., says the return of DST is a good time to examine your individual sleep pattern. Along with diet and exercise, sleep is one of the keys to maximize your health.

“The conversion to DST, with its forced loss of one hour of sleep and a change in sleep schedule, can sometimes result in complaints of disrupted daytime functioning,” said Dr. Kramer. “This problem, surprisingly, can last as long as one to two weeks in some people, especially the ‘night-owl’ type of person.”

Daylight saving time officially begins at 2 a.m., Sunday, March 10. The spring change to DST may have a variety of negative effects on health and safety. It can disrupt your sleep and enhance restlessness, causing daytime drowsiness. Research even suggests that the loss of sleep caused by springing forward one hour may be related to an increase in heart attacks and traffic accidents following the time change.

AASM offers the following tips to help you cope with the upcoming change to DST:

• Try to go to bed 15 or 20 minutes earlier each night before the time change. This will give your body a chance to adjust.
• Begin to adjust the timing of other daily routines that are “time cues” for your body.  For example, start eating dinner a little earlier each night
• On Saturday night, set your clocks ahead one hour in the early evening. Then go to sleep at your normal bedtime.
• Try to go outside for some early morning sunlight on Sunday.  The bright light will help set your “body clock,” which regulates sleep and alertness.
• Be careful when driving or operating machinery if you feel drowsy on Sunday.
• Stick to your bedtime on Sunday night to get plenty of sleep before the workweek begins on Monday.

The American Academy of Sleep Medicine considers sleep disorders an illness that has reached epidemic proportions. Board-certified sleep medicine physicians in an AASM accredited sleep center can provide effective treatment. AASM encourages patients to talk to their doctors about sleep problems or view our searchable directory of sleep centers.

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This is the first study to definitely show that insulin activity is controlled by the body’s circadian biological clock. The study, which was published on Feb. 21 in the journal Current Biology, helps explain why not only what you eat, but when you eat, matters.

The research was conducted by a team of Vanderbilt scientists directed by professor of biological sciences Carl Johnson and professors of molecular physiology and biophysics Owen McGuinness and David Wasserman.

“Our study confirms that it is not only what you eat and how much you eat that is important for a healthy lifestyle, but when you eat is also very important,” said postdoctoral fellow Shu-qun Shi, who performed the experiment with research assistant Tasneem Ansari in the Vanderbilt University Medical Center’s Mouse Metabolic Phenotyping Center.

In recent years, a number of studies in both mice and men have found a variety of links between the operation of the body’s biological clock and various aspects of its metabolism, the physical and chemical processes that provide energy and produce, maintain and destroy tissue. It was generally assumed that these variations were caused in response to insulin, which is one of the most potent metabolic hormones. However, no one had actually determined that insulin action follows a 24-hour cycle or what happens when the body’s circadian clock is disrupted.

Because they are nocturnal, mice have a circadian rhythm that is the mirror image of that of humans: They are active during the night and sleep during the day. Otherwise, scientists have found that the internal timekeeping system of the two species operate in nearly the same way at the molecular level. Most types of cells contain their own molecular clocks, all of which are controlled by a master circadian clock in the brain.

“People have suspected that our cells’ response to insulin had a circadian cycle, but we are the first to have actually measured it,” said McGuinness. “The master clock in the central nervous system drives the cycle and insulin response follows.”

Insulin, which is made in the pancreas, plays a key role in regulating the body’s fat and carbohydrate metabolism. When we eat, our digestion breaks down the carbohydrates in our food into the simple sugar glucose, which is absorbed into the bloodstream. Too much glucose in the blood is toxic, so one of insulin’s roles is to stimulate the transfer of glucose into our cells, thereby removing excess glucose from the blood. Specifically, insulin is required to move glucose into liver, muscle and fat cells. It also blocks the process of burning fat for energy.

Insulin action – the hormone’s ability to remove glucose from the blood – can be reduced by a number of factors and is called insulin resistance. The study found that normal “wild-type” mouse tissues are relatively resistant to insulin during the inactive/fasting phase whereas they become more sensitive to insulin (therefore better able to transfer glucose out of the blood) during the high activity/feeding phase of their 24-hour cycle. As a result, glucose is converted primarily into fat during the inactive phase and used for energy and to other tissue building during the high activity phase.

“That is why it is good to fast every day … not eat anything between dinner and breakfast,” says Johnson.

The researchers also examined what happened to insulin action when the circadian clocks of individual mice are disrupted. One approach that they used was to study special “knock-out” mice that had one of the genes necessary for proper biological clock function removed. They found these mice appeared to be locked in an insulin-resistant mode around the clock comparable to the inactive/fasting phase. After feeding on a high-fat diet, they tended to gain more weight and carry more fat than wild-type mice. However, supplying them with the protein produced by the missing gene re-established their circadian rhythm, reduced their insulin resistance and prevented them from gaining excess fat.

Another approach was to place normal “wild-type” mice in a constantly lit environment that disrupted their circadian cycle. In this case, they found the mice were locked in the inactive/fasting phase, developed a higher proportion of body fat and gained more weight on a high-fat diet than wild-type mice despite actually eating less food. Obesity and the insulin resistance that accompanies it, increases the risk of diabetes and cardiovascular disease.

According to the researchers, this helps explain the increased frequency of obesity and diabetes among night-shift workers and people suffering from the disruption of their clocks and normal sleep patterns.

The researchers also found that high-fat diets disrupted the circadian clock of wild-type mice living in a normal day/night cycle. As a result, their insulin cycle defaulted to the inactive/fasting phase, which helps explain why high-fat diets lead to weight gain.

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“Circadian rhythms of 24 hours govern fundamental physiological functions in almost all organisms,” said Paolo Sassone-Corsi, the lead researcher and the Donald Bren Professor of Biological Chemistry. “The circadian clocks are intrinsic time-tracking systems in our bodies that anticipate environmental changes and adapt themselves to the appropriate time of day. Disruption of these rhythms can profoundly influence human health.”

He added that up to 15 percent of people’s genes are regulated by the day-night pattern of circadian rhythms.

The results are detailed in two companion pieces that appeared the week of January 21 in the early online edition of the Proceedings of the National Academy of Sciences.

In one study, Sassone-Corsi and colleagues found that the biological clock controls enzymes localized in the mitochondrion, a cellular structure devoted to energy metabolism. This government occurs through acetylation of proteins, a process that operates as a switch to turn genes on and off in cells based upon the cells’ energy usage.

Some of the most important acetylation events in cells are dictated by an enzyme protein called SIRT1, which senses energy levels in the cell. Its activity is modulated by how many nutrients a cell is consuming. It also helps cells resist oxidative and radiation-induced stress. SIRT1 has been linked to the inflammatory response, diabetes and aging.

Sassone-Corsi first showed the circadian rhythm-metabolism link in 2008 and 2009, and in this study, he and his colleagues reveal the metabolic pathways through which SIRT1 works.

“When the balance between clock proteins is upset, normal cellular function can be disrupted,” said Sassone-Corsi.

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This information could help in planning medical treatments and monitoring the conditions of vulnerable patients.

“Virtually all physiological processes have a circadian rhythm, meaning that they occur predominantly at certain parts of the day,” says the study’s co-author Dr. Clifford Saper. “There’s even a circadian rhythm of death, so that in the general population people tend on average to be most likely to die in the morning hours. Sometime around 11 a.m. is the average time.”

The study appears in the November 2012 issue of the Annals of Neurology. The study originated several years ago while first author, Andrew Lim, and others were working in the lab of BIDMC studying why older people have trouble sleeping. The study intended to identify precursors to Parkinson’s or Alzheimer’s disease. Participants underwent various sleep-wake analyses using a wrist actigraph. The device records activity patterns to identify sleep and wakefulness. Subjects also agreed to donate their brains after they died. The group also had their DNA genotyped and compared to their wake-sleep behavior.

People with the A-A gene variation woke up about an hour earlier than did the people with the G-G gene variation. Those with the A-G gene variation woke up almost exactly in the middle.

When the investigators went back and looked at the people in the study (many of whom had enrolled more than 15 years ago at age 65) who had died, they found that this same gene variation predicted six hours of variation in the time of death: Those with the A-A or A-G gene variation died just before 11 a.m., like most of the population, but those with the G-G gene variation on average died at just before 6 p.m.

“So there is really a gene that predicts the time of day that you’ll die. Not the date, fortunately, but the time of day, says Saper.

The authors of the study said that additional work is needed to determine the mechanisms by which this and other gene variations influence the body’s biological clock. In addition to helping people optimize their schedules, the research could eventually lead to novel therapies to treat disturbances of this clock as seen in jet lag or shift work.

“Also, working out which causes of death are influenced by gene variations like the one we identified may eventually lead to rational timed interventions – such as taking heart medications at particular times depending on which version of the gene variation one carries – to provide protection during an individuals’ period of greatest risk,” says Lim. The potential clinical applications may be as diverse as the many processes that the circadian clock controls.

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It is normal for sleep habits and activity cycles to change a bit as the seasons change, according to Dr. Emerson M. Wickwire, Sleep Medicine Program Director at Pulmonary Disease and Critical Care Associates in Columbia, Md., assistant professor at Johns Hopkins School of Medicine. If you experience excessive daytime sleepiness or fatigue or a noticeable change in your mood, irritability or ability to think or remember clearly, then you should talk to a board-certified sleep physician.

“The biggest mistake that people make when it comes to sleeping in winter is ignoring their body’s natural rhythm. Even if you’re tempted to stay in bed or on the couch all day long, unless you are sick it’s a good idea to get up and move around.”

Staying in bed or on the couch all day long when you’re not sick may throw off your circadian rhythms. The visual cues of light and darkness “set” this internal clock keeping it synchronized to a 24-hour cycle.

A number of sleep disorders that are linked to misaligned circadian rhythms including insomnia, jet lag and shift work disorder. Abnormal circadian rhythms have also been blamed for depression, bipolar disorder and seasonal affective disorder, which is more common in the winter.

Winter Sleep Tips

• Increase exposure to light
• increase or maintain physical activity
• Use a humidifier or nasal rinse to keep your airway passages from drying out
• Make sure that your bedroom is not too warm or too cold

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