Can Bees Teach Us About Sleep, Learning and Memory?

As I’ve mentioned in previous blogs, we live in an exciting time for sleep research—it seems that every month, new studies are being published that provide us greater insight into the causes and treatments for various sleep disorders. And this month was no exception.

In a new article entitled, “Sleep-deprived bees have difficulty relearning”  in The Journal of Experimental Biology, researcher Randolf Menzel of the Institute of Biology in Berlin, Germany explains his four-decade study with bees, and what the results are teaching us about the effect of poor sleep on memory and learning.

The phases of sleep known as rapid eye movement (REM) and slow wave sleep (SWS) are involved in cognitive memory, such as learning motor skills and consciously remembering. As a result, restorative sleep not only rejuvenates us, it also helps consolidate memories.

To learn more about this relationship between the brain, sleep and memory consolidation, Menzel spent the last four decades studying honey bees. Why bees you ask? Well, according to Menzel, they are easy to train and well-motivated. Also, the human brain is too complex to dissect the neurocircuits that are linked to our memories. With bees, Menzel could identify the tiny circuits that control specific behaviors in their brains.

For the study, Menzel and his colleague, Lisa Beyaert, investigated the ability of bees to learn new routes from their beehive to a new feeding site, and second, the effect that loss of sleep would have on the bee's ability to learn the new route.

They provided a hive with a well-stocked feeder and trained the bees to visit the feeder and return home. To track the bees' flight during the experiments, the researchers used tiny radar antennas glued to the backs of the bees.

Once the researchers saw that the bees had memorized the route from the hive to home, they intercepted some of the bees at the feeder and transported them to a new location before releasing them again to find their way home. For the second part of the experiment, the researchers shook the bees awake every five minutes at night.

The researchers found that the insects could remember the way back to the hive after they had found it one time. However, when the scientists interrupted the bees’ sleep just after they had learned a new direct route, the bees were disoriented during the second attempt to return home.

Fewer than half the disoriented bees found their way back to the hive, and it took them twice as long as the bees with the usual amount of sleep. Menzel explained, "Without sleep, the bees are not able to consolidate the memory of the previous experiences with the new experience. Formation of the new memory is only possible during sleep.”

The well-rested bees, on the other hand, were able to find the direct way home after some brief training, but the sleep–deprived bees were disoriented and struggled to find their way. As in humans, sleep helps animals to store new experiences in such a way that earlier memories can be altered and supplemented. In other words, sleep helps us create new memories that override the previous memories.

So, what can bees teach us from Menzel’s study? That healthy, restorative sleep is vital to learning and consolidating memories. So get some good sleep tonight. That goes for you too, bees.

Read more about Menzel’s study in the article, “Sleep-deprived bees have difficulty relearning” in The Journal of Experimental Biology.

Veterans with Sleep Apnea: A Growing Human Issue

Whether or not you personally know someone who has served in Iraq, Afghanistan or someplace else on foreign soil, our returning veterans deserve our help and attention. While many have the scars of physical injury, many more veterans bear silent scars. A little known fact but of increasing concern in the medical community is that a growing number of veterans are suffering from obstructive sleep apnea (OSA), and its symptoms can be devastating for our returning war heroes as they readjust to civilian life

Consider these statistics: According to the U.S. Department of Veterans Affairs (VA), one out of every five war veterans has been diagnosed with OSA — compared with only five out of 100 civilians in the general population. And between 2008 and 2010, the number of veterans who received medical benefits related to sleep apnea grew by 61 percent, from 39,145 cases in 2008 to 63,118 cases in 2010.

These numbers beg the question: Why do war veterans suffer from sleep apnea more than non-war veterans and civilians? Some VA doctors believe that it is due to the high number of repeat deployments to Iraq and Afghanistan — soldiers are being exposed to higher levels of dust, smoke, stress and violence.

But what is at the core of this connection between war, OSA and other related conditions, such as daytime sleepiness, memory loss, a decrease in work productivity, obesity, heart disease, diabetes, and hypertension. Researchers at the Wayne State University (WSU) School of Medicine are beginning to find out.

Since the mid-2000s, WSU researchers have been studying 145 American immigrants who left Iraq before the 1991 Gulf War, and 205 who fled Iraq after the Gulf War began. All lived in the Detroit area at the time, and were asked about socio-demographics, pre-migration trauma, how they rated their current health, physician-diagnosed and physician-treated OSA, and any somatic and psychosomatic disorders.

The study’s lead investigator, Bengt Arnetz, M.D., Ph.D., M.P.H., School of Medicine professor of occupational and environmental health, and deputy director of the Institute of Environmental Health Sciences at Wayne State said, “It may be the stress of war that leads to fractured sleep, and that no one had explored this possible link before, although basic research suggests it as plausible.”

The results of the study are published in the October 2012 issue of Psychosomatic Medicine in the article, "Obstructive Sleep Apnea, Post-traumatic Stress Disorder, and Health in Immigrants.” The research showed that those who left Iraq after the war began and suffered from mental disorders such as post-traumatic stress disorder (PTSD) and depression, and self-rated their physical health as worse than their actual health, were 43 times more likely than pre-Gulf War immigrants to report OSA and later develop major chronic health issues, such as cardiovascular disease.

On the results, Arnetz said, “It's a known fact that the more exposure to violence you have, the more likely you are to report post-traumatic stress disorder (PTSD) and depression, and the worse your self-rated health is, the more likely your actual health will suffer in five to 10 years.” And I reiterate, those who were exposed to the violence of the war in Iraq were almost twice as likely to experience PTSD and depression, but also Obstructive Sleep Apnea and other chronic health conditions. I applaud Arnetz and his colleagues’ efforts, and encourage them to continue their studies so that we in the medical community can better understand, diagnose and treat war- and stress-related health conditions.

What about treatment? Diagnosing OSA in veterans can be trickier than non-veterans because of the possibility of other military-related medical conditions, such as PTSD. In addition, some military veterans suffering from OSA may underestimate the health benefits of restorative sleep, rather than be properly diagnosed and treated since its common during deployment to have fractured sleep patterns.

The good news is that there is more awareness of OSA than ever before, especially within the military. Back in February 2012, Ventus Medical, the company that makes Provent Therapy, announced that the U.S. Department of Veterans Affairs approved a multi-year, Federal Supply Schedule contract that would enable more veterans to get Provent Therapy treatment — a small, non-invasive nasal device for the treatment of obstructive sleep apnea (OSA).

This is good timing, considering that a substantial percentage of veterans don't accept or adhere to continuous positive airway pressure (CPAP) therapy, even though it is a safe and effective treatment. According to Richard B. Berry, M.D., Professor of Medicine at University of Florida, "There is a great need for access to new, clinically-proven therapies—particularly easy-to-use treatments — for the increasing number of veterans with obstructive sleep apnea."

As more and more Iraq and Afghanistan veterans are realizing their post-war health problems, and because many Vietnam veterans are getting older, the number of veterans applying for OSA-related disability benefits will only continue to rise in the coming years. While OSA is a chronic condition creating a significant burden on the Veterans Healthcare System — the VA spends upwards of $500 million a year to treat veterans with sleep apnea — I believe that it is our duty as a nation to provide proper OSA treatment to our veterans to prevent additional chronic health issues. To read more about the study, go to the Wayne State University website.

Adolescents, Poor Sleep and the Toll on Their Health

Most people consider sleep disorders such as sleep apnea, snoring and poor quality sleep an adult health issue, but research is mounting that young people may suffer from sleep disorders as much as adults do.

Earlier this year, Penn State researchers published the results of a study which showed that children who have learning, attention and/or behavior problems may be suffering from a condition known as excessive daytime sleepiness (EDS)—even if tests indicate that they are getting enough sleep at night.

And The New York Times article from April 16, 2012 entitled “Attention Problems May Be Sleep Related”  also examined the relationship between children’s sleep quality and the ability to pay attention at school.

The article was on another recent study called “Sleep-Disordered Breathing in a Population-Based Cohort: Behavioral Outcomes at 4 and 7 Years,” published in the Official Journal of the American Academy of Pediatrics.

One researcher in the article noted that cases of attention deficit hyperactivity disorder (A.D.H.D.) in children may have been misdiagnosed—that the cause of behavior such as moodiness and hyperactivity might have been due to obstructive sleep apnea (OSA) or other sleep disorder, which caused sleep deprivation in the child. Worse, the drugs prescribed for the misdiagnosed A.D.H.D. might actually be making the child’s symptoms worse.

Now, new research from The Hospital for Sick Children (SickKids) in Toronto found a link between poor sleep quality in adolescents and a host of negative health issues, including higher cholesterol levels, higher body mass index BMI, larger waist size, higher blood pressure, increased risk of hypertension and cardiovascular disease later in life.

The hospital is one of Canada’s most research-intensive hospitals, and is recognized as one of the world’s foremost pediatric health-care institutions. For the study, lead researcher Dr. Indra Narang, Director of Sleep Medicine and Staff Respirologist at SickKids, and her colleagues studied 4,104 adolescents in the Healthy Heart Schools' Program that screens and identifies teens at risk of coronary vascular disease.

The young participants slept an average of 7.9 hours during the week, and 9.4 hours on weekends. Their sleep patterns, length and quality of sleep were recorded, and data was collected on their BMIs, cholesterol levels and blood pressures. They also found out if any participants had a family history of premature cardiovascular disease.

The results of the study were published in the October 1 edition of the CMAJ — Canadian Medical Association Journal. Almost 20 percent of the adolescents reported poor sleep quality during the week, and 10 percent reported poor sleep quality on weekends. Of the participants, almost 6 percent reported using medications to help them sleep.

From the data collected, the researchers found a link between poor sleep quality—also known as sleep disturbance—and cardiovascular risk in adolescents, based on high cholesterol levels, increased BMI and hypertension. In addition, researchers found a higher sleep disturbance score in adolescents with higher cholesterol level, higher BMI, larger waist size, higher blood pressure and increased risk of hypertension.

Higher sleep disturbance scores were also found in the adolescents who consumed more fried foods, soft drinks, sweets and caffeinated drinks, exercised less and spent more time in front of computer screens. Shorter sleep duration was also associated with higher BMI and waist size. While more research is needed, the findings of the study add to compelling evidence that poor sleep quality in young people is a problem that should be addressed.
Parents, caretakers, teachers and doctors should take a young person’s “sleepy” complaints seriously, and look for clues in their behavior that may indicate sleep deprivation, including excessive daytime sleepiness and symptoms such as inattentive behavior, trouble learning and paying attention, and weight gain/obesity.

I agree with Dr. Brian McCrindle, senior author and cardiologist at SickKids, who recommends that parents do what they can now to help improve the sleep habits of children early in life, such as monitor their caffeine intake and bedtimes, and make sure their bedrooms do not have too much media, especially late at night. Doing so can help ensure that a child’s neurobehavioral challenges are properly diagnosed and treated, leading to better behavior, greater ability to learn and a happier child.

Read the full report, “Poor sleep in adolescents may increase risk of heart disease.”

Women, Wake Up: Sleep Apnea is Not Just a Male Disorder

Earlier this year, a particularly alarming statistic came out of Valme University Hospital in Seville, Spain, where researchers found that women with untreated severe OSA are three and a half times more likely to die from cardiovascular disease than women without OSA. (Read a summary of the study here.)

Since then, more research has been published showing high rates of sleep apnea in women,  as well as increasing links between OSA and age, obesity and hypertension.

In one new study published in August, researchers from Uppsala and Umeå University in Sweden analyzed 400 women between the ages of 20 and 70 years. They found that OSA was present in 50 percent of ALL the women participants aged 20 to 70 years.

They also found that 80 percent of women with hypertension and 84 percent of obese women suffered from sleep apnea. Of the obese women, 31 percent between age 55 and 70 had severe sleep apnea.

The alarming high percentages show that this should be a wake-up call to women.  Sleep apnea is not just a male disorder. Women—especially those with hypertension and/or obesity—need to wake up to the dangers of OSA and seek treatment if diagnosed with it.

Even Dr. Karl Franklin, lead author of the Swedish study, was surprised by the findings. He said, “We were very surprised to find such a high occurrence of sleep apnea in women, as it is traditionally thought of as a male disorder. These findings suggest that clinicians should be particularly aware of the association between sleep apnea and obesity and hypertension, in order to identify patients who could also be suffering from the sleeping disorder.

I agree wholeheartedly with Dr. Franklin, and add to his point that individuals, not just doctors, also need to be aware and speak up if they suspect they may have sleep apnea and related conditions. Read a summary of the study.

A few more recent studies showing OSA’s link to women’s health issues:

A study published in the September issue of the journal Obstetrics & Gynecology out of the University of South Florida found that babies born to obese women with OSA were more likely to be admitted to the neonatal intensive care unit than babies born to women without OSA. In addition, the women with OSA were more likely to develop a high blood pressure condition during pregnancy known as preeclampsia, and to deliver their babies by cesarean section.

Read the study, entitled, “Sleep apnea in obese pregnancy women linked to poor maternal and neonatal outcomes.”

In another study also published in September, sleep apnea in women has been linked to overactive bladder syndrome.

Researchers from the Hospital del Mar in Barcelona, Spain gave 72 women a questionnaire regarding their bladder control and four specific symptoms. According to the results, 62 of the women polled were diagnosed with obstructive sleep apnea (OSA). Further, the women with OSA scored higher on the questionnaire for the prevalence of bladder control symptoms, and the discomfort related with these symptoms.

More research is needed, but clearly, evidence is mounting showing the link between women and sleep apnea, and related disease and disorders. With one in four women over age 65 suffering from sleep apnea, according to the National Sleep Foundation, every woman who believes she is suffering from a sleep disorder-related condition should learn more and get checked out by a qualified sleep doctor. Many women are selfless caretakers, and will put their own worries or needs aside to take care of the needs of others. But don’t wait: Your health is the most important thing, and the healthier you are, the more productive you’ll be and the better you can care for your loved ones.

How do you know you may have obstructive sleep apnea? Some common symptoms include snoring, paused breathing during sleep and excessive sleepiness during the day. If you or someone you know is waking during the night gasping for air, that is a signal to seek diagnosis. Increased blood pressure is another sign you may have sleep apnea. For further study, read “Women and Sleep”  on the National Sleep Foundation website.

When you go for an exam, be specific with your doctor about the symptoms you are experiencing. While sleep apnea is more common in men, OSA increases in women after age 50. Many times, obstructive sleep apnea can be misdiagnosed in women as chronic fatigue, insomnia, depression, or some other non-specific condition. Also, some doctors still associate sleep apnea more with men than women, and are too quick to prescribe a medication, rather than do a full sleep disorder work up. Be  as clear and detailed as you can about your symptoms and what you are experiencing, and don’t wait —it could save your life.

Light from Tablet Computers May Delay Sleep, Especially in Teens

I admit I love my gadgets – especially my laptop and e-reader, I’m also, as a doctor, aware of the effects that the artificial light from these devices can have on our sleep, especially following prolonged and late-night use.

The artificial, short-wave light from TV and computer screens can suppress melatonin production and throw off circadian rhythm, preventing deep, restorative sleep. Prolonged sleep disruption may also lead to increased risk for diabetes and obesity.  A new study  released in late August reinforces my opinion with some data.

Researchers at the Lighting Research Center (LRC) at Rensselaer Polytechnic Institute in Troy, NY tested the effects of self-luminous tablets on melatonin suppression. Melatonin is a hormone produced by the pineal gland at night and is involved in regulating our sleeping and waking cycles.

The study was funded by Sharp Laboratories of America and led by Mariana Figueiro, associate professor at Rensselaer and director of the LRC’s Light and Health Program. Co-authors of the study are LRC director and professor Mark S. Rea, LRC research specialist Brittany Wood, and LRC research nurse Barbara Plitnick.

For the study, 13 participants used self-luminous tablets to read, play games and watch movies. The participants were divided into three groups. The first group viewed their tablets through a pair of clear goggles fitted with blue light. This was the “true positive” group because blue lights are known to be a strong stimulus for suppressing melatonin.

The second “control” group viewed their tablets through orange-tinted glasses, which filtered out the short-wavelength radiation that can suppress melatonin. The third group did not wear any glasses or goggles. Each tablet was set to full brightness.

The results of the study were clear: After only two hours of exposure to electronic devices with self-luminous “backlit” displays, the participants’ melatonin levels were suppressed by about 22 percent. According to lead researcher Mariana Figueiro, stimulation of the circadian system to this level may delay sleep in those using the devices prior to bedtime, especially in teens.

The researchers also determined that the type of task being performed on the tablets also determines how much light is delivered to the cornea, and therefore the impact the self-luminous light has on nighttime melatonin levels. In other words, the researchers pointed out that it is important to measure how much light a person receives from the self-luminous device.

So, what can be done with this new information? How can we use it to improve our sleep and general health? One, we can all become more aware of how much time we—and our children—spend staring at our tablets, computer and TV screens late at night. As adults, it is up to us to monitor ourselves and our children, and have the discipline to turn these machines off at least an hour before bedtime.

LRC research specialist Brittany Wood said, “Technology developments have led to bigger and brighter televisions, computer screens, and cell phones. To produce white light, these electronic devices must emit light at short wavelengths, which makes them potential sources for suppressing or delaying the onset of melatonin in the evening, reducing sleep duration and disrupting sleep. This is particularly worrisome in populations such as young adults and adolescents, who already tend to be night owls.”

Although pre-teens and teens love their late-night electronics, as parents, it is our responsibility to monitor our children’s computer use, or at the very least in older teens, educate them and make them aware of the potential; side effects of prolonged use.

Researcher Figueiro also feels that tablet display manufacturers can use this information to determine how their products affect circadian system regulation, and as a result, design more “circadian-friendly” electronic devices that could either increase or decrease circadian stimulation depending on the time of day. For example, screens that reduce circadian stimulation in the evening for a better night’s sleep, and increasing in the morning to encourage alertness.

Figueiro had another interesting idea about tablet light therapy: In the future, manufacturers might be able to use related data to design tablets that minimize symptoms of seasonal affective disorder, and sleep disorders in seniors. People might even be able to receive light treatments while playing games or watching movies, making light therapy much more enjoyable than just sitting in front of a light box.

Until manufacturers develop more “circadian-friendly” electronic devices that increase or decrease light exposure based on time of day, Figueiro offered several recommendations to reduce the effects of self-luminous tablet light on sleep, including dimming these devices at night as much as possible in order to minimize melatonin suppression, and, as I mentioned before, limiting the amount of time spent using these devices prior to bedtime.

Here’s another idea: Why not turn off the devices before bed, and pick up a good old fashioned paper book. You’ll be out like a light before you know it.

Read the full study entitled, “Light From Self-Luminous Tablet Computers Can Affect Evening Melatonin, Delaying Sleep.”

The Link Between Sleep Apnea and Cancer—Evidence is Mounting

September is back to school month for many of our children — it’s also a good time for adults to learn about health issues, so here is some information to help you become educated about the health risks associated with untreated sleep apnea. Evidence is mounting: severe obstructive sleep apnea (OSA) may be linked to a higher risk of dying from cancer.

The results of three recent studies in Spain were presented in early September at the European Respiratory Society’s (ERS) Annual Congress in Vienna. The data presented by the Spanish researchers reinforces the results of previous studies which show similar links between severe OSA and cancer death. 

While scientists have yet to prove 100% that sleep apnea causes a higher risk of cancer death, more and more studies are showing the link. When obstructive sleep apnea occurs, a person’s airway becomes obstructed during sleep, blocking air flow and causing the person to wake suddenly, often gasping for air. This can happen hundreds of times a night, causing a person’s blood oxygen level to drop abnormally low.

Many researcher theorize that the lack of adequate oxygen supply, known as intermittent hypoxia, caused by OSA causes increased vascular growth and tumor growth because poor breathing fails to oxygenate the cells sufficiently.

Thankfully, people with sleep apnea can be treated using multiple methods. One of the most effective is continuous positive airway pressure (CPAP) therapy, which generates a stream of air to keep the upper airways open during sleep.

Let’s look at some recent sleep apnea and cancer studies out of Spain. Dr. Miguel Angel Martinez-Garcia from La Fe University Hospital in Valencia, Spain, and his fellow researchers studied more than 5,600 sleep apnea patients from seven different sleep clinics in Spain. The researchers measured the severity of a patient’s sleep apnea, based on the number of times during the night that a patient’s blood oxygen level dropped below 90 percent oxygen saturation.

The results of the study showed that people with sleep apnea who spent more than 14 percent of their sleep time with oxygen saturation levels below 90 percent not only had severe sleep apnea, but were approximately double the relative risk of dying due to cancer than people without sleep apnea. The researchers also found a significant increase in the relative risk of dying from cancer in people with less severe sleep apnea. This association was even higher in men and younger people.

Lead researcher Dr. Martinez-Garcia stated that the results do not mean unequivocally that sleep apnea causes cancer—it means the researchers found an association between the two disorders. However, the results of the experiment add to growing evidence that there is a clear link between sleep apnea and cancer mortality. 

Research from two other Spanish studies presented at the European Respiratory Society’s Annual Congress showed an increase in cancer incidence in humans, as well as an association between sleep apnea and the spread of cancer in mice.

The second study showed an increase in all types of cancer in people with severe sleep apnea, even when other factors such as age, sex and weight were taken into account. In a third study, Spanish researchers used mice to study the spread of melanoma skin cancer, and whether this was associated with sleep apnea.

The results showed that the spread of cancer was more abundant in mice that had experienced low levels of oxygen as in sleep apnea, than those who breathed normal air during the experiment.

According to the study’s lead author, Professor Ramon Farre from the University of Barcelona in Spain, the results of the mouse study strongly suggests a link between sleep apnea and the spread of cancer, and encourages further research to better understand the links between sleep apnea and cancer.

I agree with Professor Farre that these recent studies offer compelling evidence, and it is our responsibility in the medical and scientific communities to continue researching and testing to better understand the link between sleep apnea and cancer. 

Read the full study, Sleep Apnoea Linked with Increased Risk of Cancer Death.

Less Than Six Hours Sleep/Night Increases Strokes

Lack of sleep and an increase in strokes. According to new research, the two conditions are very connected, even in otherwise healthy adults.

In early June, the University of Alabama at Birmingham released the results of a study that regularly sleeping less than six hours a night significantly increases the risk of stroke symptoms in middle-age to older adults who are of normal weight and at low risk for obstructive sleep apnea (OSA). That’s worth repeating: Less than six hours of sleep per night increases the risk of strokes in adults of normal weight and not at risk for OSA.

It seems that under six hours of sleep per night is the critical variable, but why? Let’s take a look at the study. The University of Alabama researchersfollowed 5,666 people  for up to three years who had no history of strokes or stroke-like symptoms, transient ischemic attacks (when blood flow to the brain stops for a brief period causing stroke-like symptoms), or high risk for OSA at the start of the study.

For a period of three years, the researchers followed and studied the subjects’ first stroke symptoms, stroke risk factors, depression symptoms, demographic information and other various health behaviors. What they found was—after adjusting for body-mass index (BMI)—there was a strong association between daily sleep periods of less than six hours and a greater incidence of stroke symptoms for middle-age to older adults, even beyond other risk factors. Interestingly, the researchers did not find any link between short sleep periods and stroke symptoms in overweight and obese participants.

Still, the connection between short sleep and strokes is worthy of great attention from the medical community and general public. I agree with the Alabama study’s lead author, Megan Ruiter, PhD., who said, “The results of the Alabama study provide a strong argument for increasing physician and public awareness of the impact of sleep as a risk factor for stroke symptoms, especially among persons who appear to have few or no traditional risk factors for stroke.”

It looks like the medical community is taking this message to heart. Another study announced in late July is going on at the Alberta Health Services and the University of Calgary.  There, Dr. Patrick Hanly of the university’s Hotchkiss Brain Institute is leading a study to learn more about the physiological connection between sleep apnea and stroke—specifically, the brain’s blood flow response in people with and without sleep apnea.

For the study, participants with sleep apnea stay overnight in the sleep laboratory at Calgary’s Foothills Medical Centre, where their breathing and cardiovascular responses are continuously monitored while they sleep. The next day, their brain blood flow response to reduced oxygen levels is assessed while they are awake. Then, the participants receive supplemental oxygen during sleep for two weeks, and are tested again to see if their cerebral defense mechanisms have improved. The researchers are also studying people without sleep apnea to see if their cerebral defense mechanisms function better than in those with sleep apnea. Hanly and team’s theory is that it is the lack of oxygen, or hypoxia, that people with sleep apnea experience during sleep that impairs the body’s normal defense mechanisms in the brain. A better understanding of this connection will lead to better prevention and treatment strategies.

I applaud the work of the Alabama and Calgary researchers. It’s time we all wake up to the health benefits of more–and better—sleep.

For more information, read the University of Alabama at Birmingham study, “Under 6 Hours of Sleep Tops Risks for Stroke in a Low-risk Population.”