Clock Gene Levels Linked to Insomnia and Depression

Scientists are learning why insomnia and depression are so closely interconnected. Sleep disturbances, especially early morning awakenings, are a common symptom of depression. An Ohio State University study suggests that these symptoms are related to an over-active body clock.

The so-called Clock gene helps regulate the body’s circadian rhythms. Molecular-level disturbances in the Clock gene may disrupt the 24-hour body clock, causing sleep problems.

The study compared the blood samples of people with a history of depression to those who had never been clinically depressed. The study included 60 participants; 25 spent at least five hours per week caring for a family member with dementia.

Blood analysis shows people with a history of depression had higher levels of the Clock gene. The relationship held true after statistical adjustments for age and lifestyle factors such as substance use, exercise, medical conditions and caregiving status.

Researchers also analyzed three other circadian genes, but found no statistically significant differences in gene levels between depressed and non-depressed subjects.

The authors of the study caution that the findings demonstrate there is a link, but causal direction remains unclear. In other words, further research is needed to determine whether depression causes the clock gene to be elevated, or vice versa.

Researchers explain their findings are simply a snapshot of how gene activity differs between people with and without depression.

Several other studies have attempted to explain the link between insomnia and depression.

A study published in the September 2010 issue of SLEEP suggests sleep deprivation causes depression in young adults. Every hour of sleep lost significantly raises the risk of emotional distress, a combination of high levels of depressive and anxious symptoms.

Another study presented at SLEEP 2010 in San Antonio reported similar findings, but for teenagers. Students who reported problems with daytime sleepiness were three times more likely to have depression compared to their peers.

In any case, the treatment options for depression and insomnia often overlap. While medication can help in the short term, cognitive-behavioral therapy is the best approach for lasting results. Conquering depression and insomnia takes a lot of work, but your health and happiness are worth the effort.

TED Talks Sleep, Circadian Rhythms

The far-reaching, free exchange of ideas known as TED takes on sleep and circadian rhythms in the latest streaming TEDtalk.

In the video, environmental journalist Jessa Gamble shares some things she picked up while living in the 24-hour darkness of northern Canada in the wintertime.

Gamble praises the benefits of setting an early bedtime, and waking for a couple hours in the middle of the night, before sleeping until sunrise.

The speaker's approach to sleep isn't all that different from the split sleep schedules used by astronauts and shift workers. The concept is called biphasic sleep, and research shows it can be just as effective as normal nighttime sleep.

The key is allowing enough time to complete sleep cycles. It takes about 90 minutes to reach restorative REM sleep, so short naps won't cut it.

Some of the other concepts the speaker introduces are also grounded in sleep medicine. She mentions how people living in bunkers drift forward by small increments every day. Its true the brain relies on timing cues such as light or a wristwatch. The same phenomenon occurs every day in neon light-filled casinos.

Learn more about the natural body clock and alternative sleep schedules on the Sleep Education Blog.

Trapped Chilean Miners Struggle to Sleep

A half mile under the Chilean desert, 33 men are in the early stages of an ordeal no human should ever experience. They’re trapped together in a pitch-black 600-sq-ft mining chamber for at least the next several months.

Weeks ago, the men were presumed dead in a mining accident. Everything changed this week with the bombshell announcement by the President of Chile. Rescuers discovered a note tied to a rescue probe claiming each of the 33 miners survived the cave-in. They were confirmed alive a short time later when the rescue team made contact through a narrow ventilation pipe – a lifeline for food, water and communication.

The unsettling reality of the situation quickly overshadowed the initial celebration. The trapped miners face the next 4-5 months entombed in living hell.

Almost every aspect of the story is grim. The mental toll on the minors has to be unimaginable. The promise of rescue exists, but it’s not definite. Rescuers have no room for error as they dig a new tunnel system to reach the chamber. One mistake could extinguish any remaining hope.

There is always the possibility of violence. A single mental breakdown or hotheaded argument could escalate to a tragic outcome.

The miners’ day-to-day experience is equally as horrifying. The chamber is a stagnant 90°F. It’s boring. The only light comes from flashlights on the men’s helmets.

The miners’ don’t stand a chance at getting restful sleep. The human sleep-wake cycle is regulated by natural light. Circadian rhythms run wild in the absence of sunlight. It’s conceivable that every miner is operating on a different sleep cycle.

The impact on sleep is similar to what astronauts experience on long missions. Unlike astronauts, these men have no way to prepare or adapt to living without natural sunlight.

Similar to how astronauts use work such as experiments to cope with sleep deprivation, the workers are trying to stay busy in their waking hours. They’re spending their time doing menial work and playing cards and dominos.

The comfort issue is another sleep-killer for the miners. The men are crammed together in a small, hot space. Noise disturbances are constant. There are no beds, so the men sleep on the stone floor or makeshift cots made from rocks.

Fortunately, the miners appear to be in good spirits. A video message recorded on a micro-sized camcorder shows the group singing and cheering. Although some appear emaciated, officials are confident they the men can stay alive until rescuers reach them. That could happen as early as next month, or as long as December.

Severe Alcoholism Destroys Sleep-Regulating Rhythms

A body clock broken by alcoholism may never tick again. New research shows chronic drinking can permanently damage the genes that regulate our sleep cycle.

It takes hard work and dedication to make a full recovery from alcoholism. It’s unclear if a full sleep recovery may ever follow.

The study was published on the website for Alcoholism: Clinical & Experimental Research. A print version will be included in the November 2010 issue of the journal.

Authors of the small study examined blood samples from 22 male patients who fit the DSM-IV criteria for alcohol dependence. Researchers compared the blood samples to a control group of 12 healthy men.

The alcohol dependence patient’s blood samples had lower baseline levels circadian clock gene expression. This means the patients have an elevated risk for sleep problems, as well as depression and cancer.

Findings show the circadian clock genes did not improve after the patients were put through early alcohol withdrawal treatment.

The findings are in line with a 2005 review by the AASM. Decades of studies show alcohol disrupts the sleep cycle. The relationship is dose dependent; frequent drinking can cause serious, long-term sleep problems.

Moderate drinking can also cause short-term sleep disruptions. Social drinkers may notice that alcohol can help them fall asleep, but they wake up feeling fatigued. Alcohol changes your sleep architecture. Time spent in restful REM sleep is replaced by deep, slow-wave sleep.

As the beer ads on television always say, if you drink, please drink responsibly. Drink in moderation and avoid using alcohol near bedtime.

Circadian Signs Found in Hair Samples

You can find out a lot about a person’s health just by taking a hair sample. Employers and police use hair tests to detect traces of alcohol, cocaine, marijuana, meth and many more oft-abused substances. Your doctor can tell you if you have any vitamin, mineral or nutritional deficiencies from a few dozen strands. And now researchers are learning hair tests can show when we are supposed to sleep and whether our body clocks are off track.

Findings published in the Proceedings of the National Academy of Sciences suggest hair sample testing may help specialists in sleep medicine diagnose circadian rhythm disorders. Hair follicle cells from the head or chin hair contain clock gene expressions. In other words, the amount of the genetic material RNA in your hair shows whether you’re supposed to be alert. Your hair has the most RNA during peak hours.

The Japanese authors repeatedly took hair samples from volunteers as they continued their daily routines. Over the course of three weeks they adjusted their schedule by four hours. Hair samples show their peak activity was still about two hours off, meaning their body clocks weren’t adjusted to the new sleep schedule.

The effect was magnified for rotating shift workers. Their body clock differed from their sleep-wake schedule by an average of five hours.

Beard hair worked best for the tests: researchers needed only three strands to detect circadian rhythms. It took about five head hairs for people with thick hair and up to 20 for thin head hair.

The technique is still in its infancy but has potential for clinical use, the authors argue. Hair samples could potentially tell us our chronotype and diagnose circadian rhythm disorder, jet lag and shift work disorder.

Read more about chronotypes and shift work on the Sleep Education Blog.

Image by Sciencehealth

Animals & Sleep: Clockless Reindeer and Falling Seals

Research continues to show how sleep differs among animals.

One study published last month examined the daily, “circadian” rhythms of reindeer. Researchers from the U.K. and Norway found that its melatonin production is not controlled by a circadian clock.

“The molecular clockwork that normally drives cellular circadian rhythms is evidently weak or even absent in this species,” the authors concluded.

Melatonin is a hormone that is produced in the brain. It helps your body regulate the sleep/wake cycle.

An internal body clock helps control melatonin production. Natural daylight – and the lack of it at night – also helps drive this cycle.

But melatonin production in reindeer appears to be driven only by light and darkness. This has little effect on their sleep patterns, reports LiveScience.

Reindeer sleep after they eat. As ruminant animals, they tend to eat eight to 10 times a day.

Another recent study took a closer look at northern elephant seals. They never come out on land during long migrations of up to eight months at sea.

They almost constantly make repetitive, deep dives. And they rarely surface for more than a few minutes at a time. So when do they sleep?

A research team from Japan and the U.S. studied six juvenile seals. They measured body position and 3-D diving paths.

They found that the seals sank quickly to a depth that would be safer from predators. Then they rolled over and sank on their backs during slower “drift” dives. They wobbled in a way that resembled a falling leaf.

This drastically slowed their descent rate. As a result they had time to rest or process food.

The authors also suspect that the seals may sleep during the descent phase of these dives. A few seals that drifted in shallow areas even hit the seafloor without reacting, reports Natural History.

Read more about animals and sleep.

Image by Tristan Ferne

Teens & Delayed Sleep Phase Disorder

Some people have a circadian clock that makes them “evening types.” These “owls” have a natural tendency to stay up late at night and sleep late in the morning.

Children tend to become night owls as teens because of a shift in the timing of their circadian clocks. This change causes them to feel sleepy later at night. As a result they also prefer to wake up later in the morning.

But as CNN reported last week, some teens may have an extreme change in the timing of their body clock. They may be unable to fall asleep until late at night or early in the morning. Then they may want to sleep until later morning or early afternoon. This problem is called delayed sleep phase disorder.



Insomnia symptoms can be severe when a person with DSP tries to go to sleep at a “normal” time. Excessive daytime sleepiness also can occur when he or she has to wake up early in the morning.

Teens with DSP can have a hard time in school. It can be difficult for them to conform to an early morning school schedule.

But there are effective treatments for DSP. It can be treated by taking melatonin in the afternoon or early evening. Another option is to use bright light therapy in the morning.

Both treatments can help “re-set” the body clock of a person with DSP. This can help normalize the timing of sleep.

“The way to treat delayed sleep phase is give light, in particular blue light like the light in the sky,” AASM member Dr. Jeffrey Durmer told CNN. “It activates a part of the eye that activates a part of the brain that keeps the circadian rhythm under control.”

DSP treatment should be supervised by a board-certified sleep specialist. It is important to determine the proper timing and dose of treatment that is required.

Get help from a board-certified sleep specialist at an AASM-accredited sleep center near you.

Last month a study reported that teen sleep patterns may be disrupted by a lack of exposure to morning sunlight. The researchers proposed that the problem can be solved by designing better school buildings.

Read more about sleep and teens.

Sleepy Teens Need to See the Light

A new study reports that teen sleep patterns may be disrupted by a lack of exposure to morning sunlight.

The study took place at a middle school in Chapel Hill, N.C., that has good daylight design. South-facing skylights allow plenty of natural light to enter nearly all spaces of the building.

Eleven eighth-grade students wore orange goggles for a five-day school week. The goggles prevented short-wavelength, “blue” light from reaching their eyes.

This light plays an important role in helping to set the body’s circadian clock. This timing system helps regulate sleep and wakefulness.

In the evenings the researchers measured the children’s “dim light melatonin onset.” This is the time when the body produces more melatonin.

This hormone is a “darkness signal” for the body. Sleep tends to occur about two hours after melatonin onset.

Results show that melatonin onset was delayed about six minutes per day. This added up to a delay of about 30 minutes by the end of the week.

The authors report that this delay may contribute to later sleep times and shorter sleep durations in teens. Early school start times may contribute to the problem by reducing exposure to morning sunlight.

“These morning-light-deprived teenagers are going to bed later, getting less sleep and possibly under-performing on standardized tests,” lead researcher Mariana Figueiro said in a news release. “We are starting to call this the teenage night owl syndrome.”

Figueiro added that the problem can be solved by designing better school buildings. One sponsor of the study was the U.S. Green Building Council.

“The situation in schools can be changed rapidly by the conscious delivery of daylight, which is saturated with short-wavelength, or blue, light,” she said. “Delivering daylight in schools may be a simple, non-pharmacological treatment for students to help them increase sleep duration.”

Figueiro is the program director of the Lighting Research Center at Rensselaer Polytechnic Institute in Troy, N.Y. At LRC they have created a small device called a “Daysimeter.” It measures a person’s exposure to short-wavelength, blue light.

Read more about sleep and teens.

Bipolar Disorder in Children May Be Linked to a Circadian Clock Gene

A new study found that the circadian clock gene RORB may be involved in bipolar disorder in children.

The study analyzed the genetic make-up of 305 children with bipolar disorder. They were compared with 140 controls.

Results show a positive association between bipolar disorder and four variants of the RORB gene. The authors suggest that this gene may be an important target in the search for the molecular basis of bipolar disorder.

The study also notes that bipolar disorder often involves a decreased need for sleep. This symptom helps discriminate children with bipolar disorder from those with ADHD.

The NIMH reports that bipolar disorder is a brain disorder. It is also known as manic-depressive illness.

It causes unusual shifts in mood, energy, activity levels and the ability to carry out daily tasks. These symptoms tend to be severe.

Bipolar disorder often develops in a person's late teens or early adult years. But some people have their first symptoms during childhood.

The disorder tends to run in families. Children are four to six times more likely to develop bipolar disorder if a parent or sibling has the illness.

Currently there is no cure for bipolar disorder. But ongoing treatment can help control the mood swings and other symptoms.

In 2008 FRONTLINE reported that bipolar disorder was long believed to exist only in adults. But in the mid-1990s it began to be diagnosed at much higher rates in children. Now one million children in the U.S. have been diagnosed with bipolar disorder.

Earlier this year the Sleep Education Blog reported that sleep problems in children may predict the future onset of depression. Learn more about sleep and children.

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Sleep & Weight Gain: Watch When You Eat

A new study of mice provides the first causal evidence that links meal timing and increased weight gain, reports Northwestern University. The study suggests that eating when you should be sleeping may lead to weight gain.

It might seem easy to eliminate a late-night snack; but meal timing can be a problem for shift workers.

"One of our research interests is shift workers, who tend to be overweight," said lead author Deanna M. Arble. "Their schedules force them to eat at times that conflict with their natural body rhythms.”

The researchers fed mice a high-fat diet over a period of six weeks. Some ate during naturally wakeful hours; others ate when they normally would be asleep.

Mice that ate during normal sleeping hours had a 48-percent weight gain; mice that ate the same type and amount of food during naturally wakeful hours had only a 20-percent weight gain.

A 2008 review by Northwestern researchers explored the links between sleep and energy metabolism. The review suggests that sleep loss and obesity may be "interacting epidemics." It also indicates that the circadian clock system plays a fundamental role in energy metabolism.

Earlier this year the Sleep Education Blog reported that a “sleep diet” may be one way to lose weight. Learn more about the links between sleep and weight on SleepEducation.com.

Image by Matthew

Chemotherapy Causes Sleep Problems in Breast Cancer Patients

A study published this week in the journal Sleep shows that chemotherapy for Breast Cancer, a disease with which approximately 210,000 women are diagnosed each year, impairs sleep-wake cycles in patients. Sleep disturbances can negatively affect treatment and increase risks for other health and mental problems.

Results indicate that chemotherapy patients switched from low to high activity about 30 minutes later in the day and decreased their level of activity about 50 minutes earlier at night during their first round of chemotherapy, suggesting that their days were shorter.

The study involved 95 women with an average age of 51 years, who were scheduled to receive chemotherapy for stage I-III Breast Cancer. Of the participants, 75 percent were Caucasian, 69 percent were married, 77 percent had at least some college education, and 73 percent reported an annual income of more than $30,000.

“Our biological clock, or (24-hour cycles) help keep our bodies in sync with the environment. During chemotherapy, our biological clock, or circadian rhythm gets out of sync, especially after the first cycle of treatment. The clock seems to regulate itself after only one cycle, but with repeated administration of chemotherapy, it becomes more difficult for the biological clock to readjust,” study author Dr. Sonia Ancoli-Israel told the AASM.

Sleep disturbances are common in cancer patients, with 30 percent to 50 percent reporting symptoms of insomnia. The authors state that it is important to screen more routinely for sleep disruptions in Breast Cancer patients undergoing chemotherapy and to offer treatment, such as cognitive behavioral therapy or bright light therapy, to prevent sleep disturbances from becoming chronic.

According to the AASM, studies show that cognitive behavioral therapy helps both women with breast cancer and breast-cancer survivors. It helps patients develop habits that promote healthy sleep patterns by changing actions and thoughts that hurt their ability to sleep well.

George Dawes Green’s Free-Running Circadian Rhythm Sleep Disorder

What would life be like if your sleep and wake times drifted later every day? How hard would it be if you began falling asleep in the morning, then in the afternoon, then in the evening as weeks went by?

Just ask George Dawes Green, best-selling author of The Juror. USA Today describes how he sleeps around the clock because of this rare sleep disorder.

It is a circadian rhythm sleep disorder that is known by many names. It is called “free-running type” or “nonentrained type.” Sometimes it is called “non-24-hour sleep-wake syndrome” or “hypernychthemeral syndrome.”

The disorder is closely related to light and darkness.

Normally people have a circadian rhythm that is longer than 24 hours. But during the day and at night regular timing cues reset the body clock to a 24-hour schedule.

One of these timing cues is light. The light-dark cycle has the strongest influence on the timing of the brain’s clock. Without light, it is likely that your sleep time would drift later and later each day.

This is why people who are totally blind are most likely to have free-running type. It is rare for the disorder to occur in a person like Green who has normal eyesight.

Green told USA Today that he gets eight hours of sleep per day. But his sleep-wake schedule drifts about 20 minutes later each day.

People with this disorder often become isolated. Their varying sleep schedules can make it hard to maintain relationships.

It also can be difficult to succeed in school and keep a job. Green dropped out of school because he couldn’t stay awake in class.

As an adult he tried shift work, getting a job as a night guard. Then he started his own business.

Bright light therapy and melatonin can help treat free-running type. But Green chose instead to live with the disorder and follow his own sleep schedule.

He credits this decision with helping to unleash his creativity. His new novel Ravens is out today.

Image by Russ Morris

Risk of Depression in “Evening Types” and “Morning Types”

A new study examines how chronotype may be related to depression. Is the risk of depression greater in “evening types” (“night owls”) or “morning types” (“morning larks”)?

The study involved 200 healthy adults between the ages of 18 and 99 years. Results show that people who are “evening types” have a higher risk of severe depressive symptoms.

MSNBC reports that evening types went to bed around midnight; morning types went to bed around 11 p.m. and woke up about 40 minutes earlier. Total sleep time was about the same for the two groups.

The study was unable to show if sleep schedule causes depression. But it suggests that going to bed and waking up a little earlier could improve your mood.

Yet making a change may not be easy; your DNA has a strong influence on when you prefer to sleep.

Learn more about evening and morning chronotypes.

NBA Finals: A West Coast Advantage for the Lakers?

Game one of the NBA Finals between the Lakers and Magic will tip off a little after 9 p.m. EDT tonight. The Lakers will have the home-court advantage in the seven-game series; a study in the journal Sleep shows that they also may have a West Coast advantage.

The study analyzed 8,495 regular-season NBA games over eight seasons. The researchers did not find that jet lag had a major influence on the outcome of games.

But then they did a sub-analysis of 101 games in which one team traveled across the country to play. In these games, the visiting team did four points better when they traveled west to east rather than east to west.

This may not sound like a big difference. But during the last season studied, there was only a 3.2-point difference between winners and losers in NBA games. Four points could change the outcome of a game.

Why did the West Coast teams have an edge? The authors propose that it has to do with the timing of the games.

Research suggests that athletic performance may peak in the late afternoon. Performance may decline at night as sleepiness increases.

When a game tips off at 9 p.m. in Orlando, the Lakers will be playing at a “body-clock time” of 6 p.m. They may be more alert than the Magic players.

So the Lakers may have a better chance of stealing a game on the road. Then again, it was the East Coast Celtics who won a road game in Los Angeles on the way to a 4-2 series win in the 2008 Finals.

The Magic players aren’t the only ones who face an uphill battle in this series; their fans will be put to the test too.

The Orlando Sentinel reports today that the late tip-off times during the playoffs are depriving Magic fans of sleep. When it comes to sleep, Lakers fans have their own West Coast advantage.

Image by Dale Chumbley

Morning Larks vs. Night Owls: A Circadian Alertness Advantage?

People who are larks function better in the morning. Night owls are more alert in the evening. But which “chronotype” enables people to function better over the length of a day?

A new study in Science takes a look. It involved 16 early morning risers and 15 night owls. They performed alertness tests in a brain scanner after following their normal sleep schedule.

Newsweek and Science report that both groups performed well when they took the test 1.5 hours after waking. But the night owls pulled ahead when both groups were tested after being awake for 10.5 hours. They were more alert and had faster reaction times. Overall their performance improved by about 6 percent.

So do night owls have a natural alertness advantage over morning larks? Not necessarily.

Health News points out that an advantage in the lab may not translate to the workplace. A person who is a “morning type” will be alert during the hours of a normal workday. But “evening types” may struggle to align their natural sleep-wake pattern with their work schedule.

How Children Affect a Mother’s Sleep-Wake Rhythm

Some women may have a natural tendency to be a “night owl.” But a new study shows that their sleep-wake rhythm may change after they have children.

The study involved 179 women. Some were mothers, some were pregnant, and some had no children.

Results show that women with children are more likely to be “morning types.” This means they would have a stronger tendency to go to bed early and wake up early.

The study found that mothers woke up about 1.5 hours earlier on weekends. Women with children also reported falling asleep faster than the other women.

Which group of women got the most sleep? The women who were pregnant had the longest average sleep duration.

Learn more about the many complex factors that can affect a woman’s sleep.

What’s Your Chronotype? Understanding the “Lark” and “Owl” Circadian Sleep Patterns

A New York Times column examines the factors that contribute to your preferred sleep schedule.

This is also called your “chronotype.” It turns out that your DNA has a strong influence on when you like to sleep.

Some people have a circadian clock that makes them “evening types.” These “owls” have a natural tendency to stay up late at night and sleep late in the morning. Children tend to become night owls as teens because of a shift in the timing of their circadian clocks.

Some night owls have delayed sleep phase disorder. This involves a struggle to conform to work or social demands. It can be difficult for them to function well during the day.

Other people are natural “morning types.” These “larks” prefer to go to bed early and wake up early. Adults often become larks as they get older.

Some larks have advanced sleep phase disorder. They fall asleep several hours before a normal bedtime. As a result, they also wake up hours earlier than most people wake in the morning.

So do larks have an advantage over owls? After all, it was Benjamin Franklin who said, “Early to bed and early to rise, makes a man healthy, wealthy, and wise.”

A study in 1998 put these words to the test. It found no evidence that larks were healthier, wealthier or wiser than owls.

Not everyone fits neatly into the categories of morning or evening types. Many people are somewhere in between the larks and the owls.

And many factors such as genetics and light exposure affect when you are sleepy and alert. A new study in the journal Sleep examined some other factors.

It involved 5,720 college students at two universities in Spain and Italy. Results show that females went to bed earlier and slept longer than males.

Nationality also had a significant effect on sleep patterns. On average the Spaniards went to bed and woke up later than the Italians.

The study even found a significant but small “season of birth” effect. Subjects born in spring and summer went to bed later than those who were born in fall and winter. A study in 1999 reported similar findings.

Image by Rachel

Research Catching Up to Jet Lag

Results from a new study in Current Biology may lead to more effective treatments for jet lag and shift work sleep disorder.

Both sleep disorders involve a disruption to your body’s circadian timing system. This system regulates the timing of when you sleep and wake.

The study shows that this disruption occurs in two separate groups of neurons in the brain. It also involves two different sleep stages.

Both groups of neurons are located in the “suprachiasmatic nucleus.” This part of the brain acts as a body clock. It regulates daily functions such as body temperature, hormone levels and sleepiness.

The study found that one set of neurons is closely linked with slow wave sleep. This is also called “deep sleep.” These neurons receive light information directly from the eyes. With these light and dark signals, your pattern of deep sleep can adjust to a new schedule in a couple of days.

Another set of neurons controls rapid eye movement – or REM – sleep. Most of your dreams occur during this stage. These neurons do not receive direct light information. As a result your pattern of REM sleep can be out of sync for a week or more when you cross time zones.

The researchers exposed lab rats to an artificial light-dark schedule. This simulated a trip from Paris to New York.

They also found that the time change disrupted the normal progression of sleep stages. There was an overlap of slow wave sleep and REM sleep right after the simulated jet lag. The rats also were more likely to enter REM sleep earlier than they should.

The study helps explain why it takes the body so long to adapt to a new time zone. After a long flight it typically takes about one day per time zone for your body clock to adjust to the local time.

Researcher Horacio de la Iglesia expects that the study will have a positive impact on treatments for jet lag and shift work.

"We can go back to the treatments that are believed to be effective and see where they might be acting in the circuitry of these neuron centers, then refine them to be more effective," he said in a University of Washington statement.

Image by Kossy

In Control of Sleep

An article in the April issue of The Scientist examines how the body controls the sleep/wake cycle.

Much is now known about the brain’s “master clock.” But studies are showing that this circadian clock isn’t in complete control of sleep. Other molecular mechanisms can override its signals when we are forced to stay awake.

Thus sleep may have biological functions that are beyond the control of the circadian clock. “It is clear,” writes the author, “that there are many factors affecting sleep.”

Read the article to find out more.

Women, Shift Work and Breast Cancer

BBC News reports that some women in Denmark who developed breast cancer after years of working night shifts are receiving compensation from the government.

Is there a clear link between shift work and breast cancer?

A 2008 review found only limited evidence. Yet there was enough data to convince the International Agency for Research on Cancer.

The IARC convened a working group in 2007. It was composed of 24 scientists from 10 countries. The experts reviewed all of the research.

They concluded that working night shifts is “probably carcinogenic to humans.” This means that shift work may be a factor “that can increase the risk of human cancer.”

The report was the basis for the Danish government’s compensation program. So far almost 40 women have received payment through the program.

How might night shifts promote breast cancer?

The exact mechanism is unclear. But it may be related to how shift work disrupts the “circadian rhythms” that are controlled by the body clock in your brain. This internal timing system regulates the daily cycle of various body functions.

It controls your body temperature and hormone levels. It also regulates your alertness.

One way the body promotes sleepiness is by producing more melatonin at night. This acts as a “sleep signal” for your body.

But light exposure during night shifts suppresses melatonin production and disrupts your sleep/wake cycle. These disruptions may promote the growth of cancerous tumors.

Get sleep tips for shift workers from the AASM.