In obstructive sleep apnea, breathing is interrupted by a physical block to airflow, despite the effort to breathe. The most noticeable sign of obstructive sleep apnea is snoring. However, not everyone who has OSA snores.

According to Medilexicon’s medical dictionary, Obstructive Sleep Apnea (OSA) is:

“a disorder, first described in 1965, characterized by recurrent interruptions of breathing during sleep due to temporary obstruction of the airway by lax, excessively bulky, or malformed pharyngeal tissues (soft palate, uvula, and sometimes tonsils), with resultant hypoxemia and chronic lethargy. Sleep in the supine position predisposes apnic episodes.”

People with OSA may experience repeated episodes of apnea during the night. The lack of oxygen causes a person to come out of deep sleep into a lighter stage of sleep in order to restore their normal breathing. Once they fall back into deep sleep further episodes of apnea can occur.

The repeated interruptions to sleep that are caused by OSA can lead to the person feeling very tired during the day. A person with OSA will usually have no memory of any episodes of breathlessness.

OSA is a relatively common condition that affects men more than women. The condition is most common in people aged 40 or over, although it can affect people of all ages, including children.

It is also especially common in people who are overweight.

OSA is a serious condition

A person suffering from the condition can experience a lack of proper sleep. As a result, their risk of being involved in a life-threatening accident, such as a car crash, is increased. The lack of sleep causes impairment in judgment and reaction time.

Also, there is some evidence suggesting that people with OSA are at greater risk of developing high blood pressure (hypertension), which can lead to a heart attack or stroke.

Obstructive sleep apnea treatment may involve using a device to keep the airway open or undergoing a procedure to remove tissue from the nose, mouth or throat.
What are the signs and symptoms of sleep apnea?
A symptom is something the patient feels and reports, while a sign is something other people, such as the doctor detect. For example, pain may be a symptom while a rash may be a sign. Signs and symptoms of obstructive sleep apnea include:
Abrupt awakenings accompanied by shortness of breath
Awakening with a dry mouth or sore throat
Difficulty staying asleep (insomnia)
Excessive daytime sleepiness (hypersomnia)
Forgetfulness
Frequent heartburn or gastroesophageal reflux disease
Frequent urination at night
Gasping, snorting
Heavy night sweats
Loud snoring (with periods of silence followed by gasps)
Mood changes such as irritability, anxiety and depression
Morning headache
Noisy breathing
Observed episodes of breathing cessation during sleep
Trouble concentrating
Unexplained daytime sleepiness
Consult a medical professional if you experience, or if your partner observes the following:
Snoring loud enough to disturb your sleep or that of others
Shortness of breath that awakens you from sleep
Intermittent pauses in your breathing during sleep
Excessive daytime drowsiness, which may cause you to fall asleep while you’re working, watching television or even driving a vehicle
People with OSA may have no memory of their sleep being interrupted. Over time, the repeated interruptions to sleep will lead to the symptoms of sleep deprivation. These include:
depression
feeling excessively sleepy during the day
headaches; particularly in the morning
irritability and short temper
lack of interest in sex
poor memory and concentration
in men, impotence
Some people with OSA may also find that they wake up frequently during the night in order to urinate.

Many people do not consider snoring as a sign of something potentially serious. In addition, not everyone who has sleep apnea snores. Typically, snoring is loudest when sleeping on the back. It quiets when turning on the side.

Seek medical advice about any sleep problem that leads to chronic fatigue, sleepiness and irritability.
What causes obstructive sleep apnea?
Obstructive sleep apnea occurs when the muscles in the back of the throat relax too much to allow normal breathing. These muscles support the tongue, tonsils and soft palate (a muscle at the back of the throat used in speech). Once the muscles relax, the airway in the throat can narrow or become totally blocked. This interrupts the oxygen supply to the body which triggers the brain to interrupt deep sleep so that the airway can be reopened and normal breathing is restored.

This awakening is usually so brief that the person does not remember it.

The person awakens with a temporary shortness of breath that corrects itself quickly, within one or two deep breaths. The person makes a snorting, choking or gasping sound. All night long, this pattern can repeat itself five to 30 times or more each hour. These disruptions impair the ability to reach the deep, restful phases of sleep.

Most adults require at least eight hours of sleep to function at their best and half of that time should be spent in the deepest phase of sleep.

Obstructive sleep apnea in children, unlike adults, is often caused by obstructive tonsils and adenoids and may sometimes be cured with tonsillectomy and adenoidectomy.
What are the risk factors of obstructive sleep apnea?
A risk factor is something which increases the likelihood of developing a condition or disease. For example, obesity significantly raises the risk of developing diabetes type 2. Therefore, obesity is a risk factor for diabetes type 2.

Anyone can develop obstructive sleep apnea. However, there are certain risk factors:
Obesity – the more obese a person is, the higher the risk. More than half of those with obstructive sleep apnea are overweight. Fat deposits around the upper airway may obstruct breathing. However, thin people can also develop the disorder.

A family history of sleep apnea – People with family members with sleep apnea, may be at increased risk.

A narrowed airway – People who have a naturally narrow throat. Tonsils or adenoids may become enlarged, blocking the airway.

Age – Being 40 years of age or over.

Being black, Hispanic or a Pacific Islander – Among people under age 35, obstructive sleep apnea is more common in blacks, Hispanics and Pacific Islanders.

Being male – In general, men are twice as likely to have sleep apnea. The reasons why are unknown.

Being older – Sleep apnea occurs two to three times more often in adults older than 65.

Chronic nasal congestion – Obstructive sleep apnea occurs twice as often in those who have consistent nasal congestion at night, regardless of the cause. This may be due to narrowed airways.

Diabetes – Obstructive sleep apnea is three times more common in people who have diabetes.

Having a large neck – The size of the neck may indicate whether or not there is an increased risk of obstructive sleep apnea. This is because a thick neck may narrow the airway and may be an indication of excess weight. A neck circumference greater than 17 inches (43 centimeters) for men and 15 inches (38 centimeters) for women is associated with an increased risk of obstructive sleep apnea.

Having an unusual inner-neck structure – Such as an unusually narrow airway or unusually large tonsils or tongue or having a lower jaw that is set back further than normal.

High blood pressure (hypertension) – Obstructive sleep apnea is relatively common in people with hypertension.

Menopause – A woman’s risk appears to increase after menopause. The changes in hormone levels that occur during the menopause may cause the throat muscles to relax.

Smoking. Smokers are nearly three times more likely to have obstructive sleep apnea.

Taking medicines that have a sedative effect – Such a sleeping pills or tranquillizers.

Taking the anti-impotence medicine sildenafil (Viagra) – There is some evidence to suggest that sildenafil can cause the throat muscles to relax.

Use of alcohol, sedatives or tranquilizers – These substances relax the muscles in the throat.
What are the complications of obstructive sleep apnea?
Sleep apnea is considered a serious medical condition. Complications may include:

Cardiovascular problems. Many people with obstructive sleep apnea (OSA) develop high blood pressure (hypertension). This also increases the risk of developing a cardiovascular disease such as a stroke or heart attack. This can lead to sudden death from a cardiac event. Sudden drops in blood oxygen levels that occur during sleep apnea increase blood pressure and strain the cardiovascular system. The more severe the obstructive sleep apnea, the greater the risk of high blood pressure. Patients with sleep apnea are much more likely to develop abnormal heart rhythms such as atrial fibrillation.

Daytime fatigue. People with sleep apnea often experience severe daytime drowsiness, fatigue and irritability. They may have difficulty concentrating and find themselves falling asleep at work or even when driving. Children and young people with sleep apnea may do poorly in school, have reduced mental development or have behavior problems. Treatment of sleep apnea can improve these symptoms, restoring alertness and improving quality of life.

Sleeping while Driving. Experiencing significant daytime sleepiness will have an adverse impact on driving ability. One study calculated that people with severe untreated OSA are 15 times more likely to be involved in a car accident. You should avoid driving until symptoms of OSA respond to treatment

Complications with medications and surgery. Obstructive sleep apnea is a concern with certain medications and general anesthesia. People with the condition may be more likely to experience complications after major surgery. This is because they are prone to breathing problems, especially when sedated and lying on their backs. Inform your doctor before having surgery. Undiagnosed sleep apnea is especially risky in this situation. Use of analgesics and sedatives in these patients postoperatively should be minimized or avoided.

Partners or family. Loud snoring can keep those around from getting good rest. This can be eventually disruptive in relationships.

People with obstructive sleep apnea may also complain of memory problems, morning headaches, mood swings or feelings of depression, and a need to urinate frequently at night.
How is obstructive sleep apnea diagnosed?
If experiencing the symptoms of excessive daytime sleepiness a useful first step may be to ask a partner, friend, or relative to observe you when you are asleep. They may be able to spot episodes of breathlessness that could help to confirm a diagnosis of obstructive sleep apnea (OSA).

Physical examination and tests

A physical examination and a number of tests, including a blood pressure test, may be carried out. This is in order to rule out other conditions that could explain tiredness, such as an under-active thyroid gland.

An evaluation may be made based on the signs and symptoms or there may be referral to a sleep disorder center. A sleep specialist can help decide whether there is need for further evaluation. The evaluation may involve overnight monitoring of breathing and other body functions during sleep. This can sometimes be done in sleep centers which are specialist clinics or hospital departments that help treat people with sleep disorders.
Nocturnal polysomnography. During this test, the patient is hooked up to equipment that monitors the heart, lung and brain activity, breathing patterns, arm and leg movements, and blood oxygen levels while sleeping.

Oximetry. This screening method involves using a small machine that monitors and records blood oxygen level while sleeping. A simple sleeve fits painlessly over one finger to collect the information overnight at home. The results of this test will often show drops in blood oxygen level during apneas and subsequent rises with awakenings. However, oximetry does not detect all cases of sleep apnea.

Portable cardiorespiratory testing. Under certain circumstances, the patient may be provided with at-home tests to diagnose sleep apnea. These tests usually involve oximetry, measurement of airflow and measurement of breathing patterns.
The patient may also be referred to an ear, nose and throat doctor (otolaryngologist) to rule out any anatomic blockage in the nose or throat.

The severity of OSA is judged on how many episodes of apneas are experienced over the course of an hour. The number of episodes determines mild, moderate, and severe OSA:
Mild OSA – between 5 to 14 episodes an hour.
Moderate OSA – between 15 to 30 episodes an hour.
Severe OSA – more than 30 episodes an hour.
What is the treatment for obstructive sleep apnea?
Lifestyle changes may be recommended for milder cases of obstructive sleep apnea, such as losing weight or quitting smoking. If these measures do not improve the signs and symptoms or if the apnea is moderate to severe, a number of other treatments are available:

Therapies

Positive airway pressure. For moderate to severe sleep apnea, a machine that delivers air pressure through a mask placed over the nose while sleeping may be recommended. The most common type is called continuous positive airway pressure (CPAP). With this treatment, the pressure of the air breathed is continuous. The compressed air prevents the airway in the throat from closing. This prevents apnea and snoring.

CPAP is the most commonly used method of treating sleep apnea. However, some people find it awkward and uncomfortable. Most people learn to adjust the mask to obtain a comfortable and secure fit. Some people also benefit from using a humidifier along with their CPAP system.

Do not stop using the CPAP machine. Check with your doctor to see what adjustments can be made to improve its comfort. Also, after weight changes, your doctor may need to adjust the pressure settings.

Mouthpiece (oral device) or Inter-oral devices (IODs). Wearing a mouthpiece designed to keep the throat open is another option. Oral appliances are a successful alternative for some patients. Some are designed to open the throat by bringing the jaw forward. This can sometimes relieve snoring and mild obstructive sleep apnea. Others hold the tongue in a different position. Advice from a dentist experienced in dental sleep medicine appliances is required for the fitting and follow-up therapy.

Surgery or other procedures

The goal of surgery is to remove excess tissue from the nose or throat that may be vibrating and causing the snoring. The excess tissue may be blocking the upper air passages and causing sleep apnea. Surgical options may include:
Surgical removal of tissue. Uvulopalatopharyngoplasty (UPPP) is a procedure in which the tissue from the rear of the mouth and top of the throat is removed. The tonsils and adenoids are commonly removed as well. UPPP usually is performed in a hospital and requires a general anesthetic.

Jaw correction. This procedure is called maxillomandibular advancement. The upper and lower parts of the jaw are moved forward from the rest of the facial bones. This enlarges the space behind the tongue and soft palate, making obstruction less likely. This procedure may require an oral surgeon and an orthodontist

Surgical opening in the neck. This form of surgery may be needed if other treatments have failed and the patient has severe, life-threatening sleep apnea. In this procedure, called a tracheostomy, an opening in the neck is made. A metal or plastic tube is inserted for breathing. The opening is kept covered during the day. But at night it is uncovered to allow air to pass in and out of the lungs, bypassing the blocked air passage in the throat.

Implants. The Pillar procedure is a minimally invasive treatment. It involves placement of three tiny polyester rods in the soft palate. These inserts stiffen and support the tissue of the soft palate and reduce upper airway collapse and snoring. This treatment is recommended only for people with mild to moderate obstructive sleep apnea.
Removing tissues in the back of the throat with a laser (laser-assisted uvulopalatoplasty) or with radiofrequency energy (radiofrequency ablation) are procedures that are sometimes use to treat snoring. However, these procedures are not recommended for treating obstructive sleep apnea.

Other types of surgery: They may help reduce snoring and sleep apnea by clearing or enlarging air passages:
Nasal surgery to remove polyps or straighten a crooked partition between the nostrils (deviated nasal septum)

Surgery to remove enlarged tonsils or adenoids
Stimulants

If symptoms of daytime sleepiness are particularly severe, a short-term dose of a medicine known as a stimulant may be recommended. Stimulants work by increasing the activity within the nervous system in order to make the patient feel more alert and awake.

A medicine called modafanil may be recommended. Side effects of modfanil can include dizziness and blurred vision. In rare situations, modafanil can cause depression and make people think suicidal thoughts. The long-term use of stimulants is not recommended because they can become addictive.

Alternative treatments

Treatment is offered by speech therapists to strengthen the muscle tone and neural pathways involved in breathing.

Breathing exercises, such as those used in Yoga, the Buteyko method, or didgeridoo playing can be effective. There are muscles which act to tension and open the airway during each inspiration. Exercises can, in some cases, restore sufficient function to these muscles to prevent or reduce apnea.

Positional treatments

Many people benefit from sleeping at a 30 degree elevation of the upper body. It helps prevent the gravitational collapse of the airway. A 30 degree elevation of the upper body can be achieved by sleeping in a recliner, an adjustable bed, or a bed wedge placed under the mattress. This approach can easily be used in combination with other treatments and may be particularly effective in very obese people. Lateral positions (sleeping on a side) as opposed to supine positions (sleeping on the back), are also recommended.

Lifestyle changes

Some cases of mild to moderate OSA can be successfully treated by making changes to lifestyle. These include:
Avoiding alcohol during the evening.

Losing weight.

Quitting smoking.

Sleeping on the side, rather than on the back, may also help to relieve symptoms of OSA.

Avoid medications such as tranquilizers and sleeping pills. These relax the muscles in the back of the throat, interfering with breathing.

Keep nasal passages open at night. If there is congestion, use a saline nasal spray to help keep the nasal passages open. Get medical advice about using nasal decongestants or antihistamines, because, unlike saline sprays, these medications are generally recommended only for short-term use.

Lead investigator Dr Matthew Walker, an assistant professor of psychology at the University of California, Berkeley, presented the preliminary findings of a study he conducted with other colleagues on Sunday, 21st February at the annual meeting of the American Association of the Advancement of Science (AAAS) in San Diego, California.

The researchers found that an hour’s nap can dramatically boost and restore brain power: it not only refreshes the mind, but can make you smarter, they suggest.

Walker told the press that:

“Sleep not only rights the wrong of prolonged wakefulness but, at a neurocognitive level, it moves you beyond where you were before you took a nap.”

For this study, Walker and colleagues recruited 39 healthy young adult volunteers and put them into two groups: a nap group and a no-nap group.

At midday, both groups performed much the same in a challenging task that involved absorbing a lot of facts.

At 2 pm, the volunteers in the nap group took a nap for about 1.5 hours while the no-nap group stayed awake, and then at 6 pm, they underwent a new set of learning exercises.

The results showed that the group that was able to take a nap in the afternoon performed better in the evening exercise than the group that had to stay awake the whole day. And not only did the nap group perform better than the no-nap group, they also performed better than they had earlier in the day, before their nap.

Walker said the findings support the idea that sleep is a necessary process that clears the brain’s short term memory storage so there is room to absorb new information.

The findings are also in line with earlier research by the same team, where they established that working through the night, which is common practice among students facing midterm and final exams, decreases one’s capacity to absorb new facts by nearly 40 per cent due to regions of the brain shutting down as a result of sleep deprivation.

Earlier studies have revealed that the hippocampus temporarily stores fact-based memories before relaying them to the brain’s prefrontal cortex.

Walker likened the process to having an email inbox in your hippocampus. This gets full, and you need to sleep to initiate the clearing out process. Until you do, then the mail stays in the inbox and you can’t take in any more.

“It’s just going to bounce until you sleep and move it into another folder,” said Walker.

Using electroencephalography, a way of measuring the amount of electrical activity in the brain, Walker and colleagues also established that the memory-refreshing process takes place in a stage of sleep known as stage 2 non-REM sleep (non Rapid Eye Movement sleep).

Stage 2 non-REM sleep occurs between deep sleep and REM sleep and nobody really knew what it was for, but now, Walker and colleagues suggest that this is when memory-clearing takes place and may explain why humans spend at least half of their sleeping time in this stage.

The team now want to find out whether there is a link between the reduction in sleep that older people tend to experience and the supposed reduction in learning capacity that occurs as we age.

Finding such a connection could help us better understand neurodegenerative diseases like Alzheimer’s, said Walker.

Watermark’s ARESTM is an innovative, low-cost, patient-friendly wireless device, offered through primary care physicians that is worn while the patient sleeps at home. The device collects physiological data and integrates it with clinical history to determine the presence and severity of obstructive sleep apnea (OSA).

John Sculley, Co-Chairman of the Board for Watermark Medical, said, “The Watermark platform helps transform the manner in which healthcare is delivered by lowering costs and focusing on outcomes and therapy compliance.”

The test results are reviewed by a certified sleep technologist and then interpreted by the patient’s physician or sleep specialist. Appropriate therapy is then recommended by the patient’s physician.

Watermark Medical Chief Medical Officer and inventor of the ARESTM, Dr. Philip Westbrook, is one of the Dr. Oz panel of experts discussing sleep apnea. He can be found on the Sleep Apnea Syndrome tab of the “Ask Dr. Oz” section of the website. See here.

Cleveland Clinic recognized Home Sleep Testing as the # 7 Top 10 Medical Innovations of 2010.

See here. Watermark Medical’s technology platform enables connectivity between the physician and the patient’s diagnostic and compliance data in a simple and cost effective manner.

Sleep apnea, which can be life threatening, is one of the most common sleep disorders. Breathing stops and then restarts again recurrently during sleep. It is one of the leading causes of disruptive snoring and excessive daytime sleepiness, and also may be responsible for job impairment and motor vehicle crashes.

Untreated sleep apnea can cause high blood pressure and other cardiovascular diseases, memory problems, weight gain, impotency and headaches, said Heyniger.

“Not enough people are getting screened, especially patients with hypertension or diabetes,” he said. “Fortunately, advances in technology make it convenient for those with sleep apnea to comfortably get diagnosed and treated.”

Source
Watermark Medical

Sleep is regulated by processes in the brain in response to how long we are awake in addition to the light/dark cycle controlled by the circadian rhythm. With Drs. Oum Hassani and Maan Gee Lee, Dr. Barbara Jones at the MNI were studying a structure in the brain called the lateral hypothalamus (LH) known to be critical for maintaining wakefulness. MCH neurons, co-distributed with Orx neurons, constitute less than 10% of the LH. Previous studies have shown that Orx neurons are essential for maintenance of the awake state. These neurons are active in the waking state and turn off during sleep and in their absence, animals and humans experience narcolepsy with cataplexy or sudden loss of mucle tone. However, the role of MCH neurons was until now, unclear. Evidence from earlier knockout studies suggested that MCH neurons might play a different role than Orx neurons in regulating activity and sleep-wake states. Therefore the team at the MNI set up experiments to study the function of MCH neurons during the sleep-wake states.

“Remarkably, what we found is that MCH neurons are actually silent during waking, which is a surprising finding especially in this wake-promoting region of the brain. The neurons fire during sleep, and are most active during REM sleep,” says Dr. Barbara Jones, neuroscientist at the MNI and principal investigator in the study. “Our study markedly demonstrates that MCH neurons discharge in a reciprocal manner to the Orx neurons across the sleep-wake cycle.” Dr. Jones and colleagues used their expertise to apply and develop a difficult technique which allowed them to selectively record, label and thus identify a nerve cell containing a particular chemical. This allowed them to isolate the functions of the MCH and Orx cells even though they comprise less than 10% of the nerve cells in the LH.

The reciprocal profiles and roles of the Orx and MCH neurons could be significant in the manifestation of sleep disorders. It is possible that narcolepsy, which occurs with the loss of Orx neurons, is provoked in part by the MCH neurons that remain intact in the narcoleptic patients. A growing body of research shows that regular and normal sleep is necessary for overall health; regulating hormone levels, blood pressure, metabolism, alertness, mood, and consolidating memory. This study presents potential therapeutic avenues and targets for the treatment of various sleep disorders including the development of drugs that will act on receptors for Orx and MCH, to stimulate or block these receptors accordingly.

The study shows that those patients who complained of nightmares during the week following the suicide attempt were three times more likely to attempt to take their own life again, regardless of gender or psychiatric diagnosis, such as depression or post-traumatic stress syndrome.

“Those who were still suffering from nightmares after two months faced an even greater risk. These people were five times more likely to attempt suicide a second time,” says author of the thesis, Registered Nurse Nils Sjöström.

Other sleeping difficulties do not increase risk of repeat suicide attempts

It is normal for patients that have attempted suicide to suffer from sleeping difficulties. Some 89 percent of the patients examined reported some kind of sleep disturbance. The most common problems were difficulty initiating sleep, followed by difficulty maintaining sleep, nightmares and early morning awakening. Nils Sjöström has also examined the possibility of there being an increased risk of repeat suicide attempts if the patient has difficulty falling asleep, difficulty sleeping during the night, or wakes up early in the morning. However, the result did not indicate any increased risk.

“The results show how important it is for healthcare staff to highlight the significance of nightmares in the clinical suicide risk assessment,” says Nils Sjöström.

“They said that I had 35 interruptions of my sleep per hour. So that meant that I was never getting fully asleep,” says Lou.

Because he was deprived of oxygen at night, Lou’s heart was being damaged, which is why he started using a continuous positive airway pressure mask, or a C-PAP mask. Doctors have known for sometime that it helps patients breathe better.

“What we haven’t known as well, is, whether or not C-PAP benefits the heart,” says Doctor Subha Raman, MD at the Ohio State University Medical Center.

So doctors at the Ohio State University Medical Center decided to find out. They took MRI’s of patients to get a good idea of the size and shape of their hearts when they were first diagnosed. Then patients were given C-PAP masks to sleep in. After several weeks they came back for another MRI, and doctors were surprised by what they saw.

“We saw that before treatment, the heart was enlarged. But after three months of careful use of their CPAP, we saw a reduction in the enlargement of the heart,” says Dr. Raman.

In all, experts say of the 13 patients who tried it, there were “significant” changes in the right ventricle of the heart.* Which means this mask not only helps with sleep disorders, but may be helping doctors get to the heart of a much more serious problem, as well.

Doctors say if left untreated, sleep apnea can lead to high blood pressure, and increase your risk of diabetes or having a stroke. If someone complains that you snore loudly and often you may want to get checked out by your doctor.

“The Sleep and Human Health Institute has a history of groundbreaking work, and this study will be an important advancement in understanding the relationship between Insomnia and Sleep Apnea,” said David P. White, M.D., Chief Medical Officer, Philips Respironics. “We know there are many skeptics who insist Chronic Insomnia is largely a psychological problem, but recent studies on certain patients have already shown that continuous positive airway pressure (CPAP) therapy or upper airway surgery significantly decreases insomnia.”

Unlike other studies that investigated patients at sleep centers, the new research will examine randomly selected patients seeking care at their primary care clinics. This approach provides data much closer to what goes on in the general population compared to sleep center cohorts.

“This opportunity will clarify whether Sleep Apnea is a common problem often overlooked in Chronic Insomnia patients,” declared Dr. Barry Krakow, principal investigator and medical director of the Sleep & Human Health Institute. “We’ll be using the latest respiratory technology to more accurately measure breathing, and we hypothesize that more than half of these Chronic Insomnia patients will suffer from previously undiagnosed Sleep Apnea.” Dr. Krakow is also medical director of Maimonides Sleep Arts and Sciences, a co-sponsor of the research.

“We have shown that ODP is consolidated by sleep,” says senior study author Dr. Marcos G. Frank from the Department of Neuroscience at the University of Pennsylvania School of Medicine. “Our previous studies indicate that the underlying mechanisms, though still unknown, may involve N-methyl D-aspartate receptors (NMDARs) and intracellular kinases.” Dr. Frank and colleagues performed a series of experiments designed to test this hypothesis.

The researchers found that sleep consolidates ODP primarily by strengthening cortical responses to stimulation of the nondeprived eye. NMDAR- and protein kinase A-mediated intracellular cascades were critical components of the cellular machinery required for sleep-dependent consolidation of ODP, and their activation during sleep promoted synaptic strengthening.

Further, sleep-specific elevations in cortical activity were observed in remodeling cortical neurons. The remodeling visual cortex exhibited a sleep-dependent activation of several kinases that are downstream of NMDARs, which also had been previously linked to learning and memory processes.

Interestingly, both blockade of NMDARs and sleep deprivation interfered with ODP consolidation. This suggests that aberrant NMDAR signaling may mediate the negative effects of sleep loss on cognitive function.

“These findings demonstrate that when the cortex is triggered to remodel in wakefulness, synaptic changes are further modified and consolidated by cortical reactivation and a secondary series of NMDAR and kinase-mediated signaling cascades during sleep,” offers Dr. Frank.

According to the principal investigator Giora Pillar, M.D, Ph.D, with the Sleep Laboratory at Rambam Medical Center in Haifa, Israel, it is very difficult to objectively assess and quantify the capability of an individual to remain vigilant. Many of the study’s participants may have been highly motivated to overcome their sleepiness during the test in order to prevent their license from being revoked.

“It could be expected that the MWT40 will be superior to MWT20, but it is somewhat surprising that despite a strong drive to sleep, as in cases of severe apnea, people could pass the test by remaining awake in all trials,” said Pillar. “It emphasizes the strong effect of motivation.”

The study included 164 consecutive subjects with an average age of 50, who were referred to the Technion Sleep Lab between June 2006 and January 2007 by the Medical Institute for Driving Safety of the Ministry of Transportation. Participants who were suspected of suffering from EDS were referred for evaluation for their ability to maintain wakefulness for the purpose of renewal of their license to drive. Seventeen of the participants were professional drivers and one participant was an aviation pilot.

All subjects underwent a full-night polysomnograph followed by an MWT40, (four 40 minute long trials). During the MWT, participants were told to sit on a bed in a reclining position in a private, dimly lit room. Subjects were not allowed to perform any unusual action to maintain wakefulness, such as reading, talking, consuming caffeine or making repetitive movements. Trials were stopped if the subject fell asleep or if 40 minutes had passed.

According to Pillar, none of the participants who were receiving continuous positive airway pressure (CPAP) treatment failed the MWT 40; this information emphasizes the importance of treating OSA in preventing auto accidents caused by EDS. Pillar noted that findings of this study indicate that further research is necessary in order to determine a more efficient way to objectively assess an individual’s ability to remain vigilant while driving.

According to the American Academy of Sleep Medicine (AASM), OSA is a sleep-related breathing disorder that involves a decrease or complete halt in airflow despite an ongoing effort to breathe. It occurs when the muscles relax during sleep, causing soft tissue in the back of the throat to collapse and block the upper airway. This leads to partial reductions (hypopneas) and complete pauses (apneas) in breathing that can produce abrupt reductions in blood oxygen saturation. Brief arousals from sleep restore normal breathing but can cause a fragmented quality of sleep. Most people with sleep apnea snore loudly and frequently, and they often experience excessive daytime sleepiness.

AASM practice parameters for the MWT recommend the 40-minute protocol and advise that the MWT be used when sleep clinicians require objective data to assess an individual’s ability to remain awake. The MWT should be used in association with the clinical history to assess the ability to maintain wakefulness.

Eighty-one percent of the women in the headache group reported going to sleep as a way of managing their headaches; this method was also rated as the most effective self-management strategy for pain.

Principal investigator and lead author, Jason C. Ong, PhD, assistant professor of behavioral sciences at Rush University Medical Center, said the extent to which the headache sufferers rated sleep as being an effective method for coping with pain was somewhat surprising.

“Insomnia is a common complaint among headache sufferers. While napping may relieve pain, it may also decrease the brain’s need for sleep at night, leading to reduced ability to initiate and maintain sleep at night,” said Ong.

The study found 58 percent of those with tension-type headaches reported sleep problems as a trigger of headaches compared to 18 percent of those who only suffer minimal headache pain. Similar studies have found that sleep disturbances, which include difficulty falling asleep or staying asleep, have been identified as a risk factor for developing chronic headaches.

Women in the headache group also reported a significantly higher rating of pain interfering with sleep compared to the control group. No significant differences were found between the groups on use of medication to relieve headaches.

Ong encourages further behavioral treatment studies to examine alternative coping strategies for pain that do not involve sleep. He notes that clinicians should be sensitive to the dilemma of managing pain and sleep disturbances.

In addition, the study concludes that medical experts should assess daytime napping behaviors among individuals who report insomnia and headaches. Such an assessment may be important for developing behavioral sleep interventions.

The study involved 65 women recruited from undergraduate psychology courses at a university located in the southeastern U.S. The average age of members of the headache group was 21.9 years, while the average age of the control group was 18.9 years.

The average time since the first headache of any type was 9.4 years for participants in the headache group, with an average of 8.11 headache days per month. Participants reported an average of 12.2 tension-type headaches over the past year, and 2.1 tension-type headaches in the past month, with a median duration of 2.0 hours. The average tension-type headache intensity rating using a 0-to-10 scale was 5.6. Six participants in the headache group also met criteria for migraine disorder.

Founded in 1978, the Sleep Disorders Center at Rush was the first such center in Illinois and the first in the region to receive accreditation from the American Academy of Sleep Medicine (then the American Sleep Disorders Association). The staff of the Sleep Disorders Service and Research Center has established a national reputation for clinical excellence, for innovation in sleep medicine research and for providing superior training to the next generation of sleep professionals.

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Article adapted by Medical News Today from original press release.
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RushUniversity Medical Center is an academic medical center that encompasses the more than 600 staffed-bed hospital (including Rush Children’s Hospital), the Johnston R. Bowman Health Center and Rush University. Rush University, with more than 1,730 students, is home to one of the first medical schools in the Midwest, and one of the nation’s top-ranked nursing colleges. Rush University also offers graduate programs in allied health and the basic sciences. Rush is noted for bringing together clinical care and research to address major health problems, including arthritis and orthopedic disorders, cancer, heart disease, mental illness, neurological disorders and diseases associated with aging.

The Journal of Clinical Sleep Medicine (JCSM), is the official publication of the American Academy of Sleep Medicine (AASM). AASM is a professional membership organization dedicated to the advancement of sleep medicine and sleep-related research. As the national accrediting body for sleep disorders centers and laboratories for sleep related breathing disorders, the AASM promotes the highest standards of patient care. The organization serves its members and advances the field of sleep health care by setting the clinical standards for the field of sleep medicine, advocating for recognition, diagnosis and treatment of sleep disorders, educating professionals dedicated to providing optimal sleep health care and fostering the development and application of scientific knowledge.