Sleep Blog

Moderate-to-severe apnea may
lead to death of brain tissue

Patients with moderate to severe sleep apnea who have significantly higher serum levels of inflammatory markers that serve as precursors to coronary artery disease, as well as lesions associated with silent brain infarction, have an elevated risk of stroke, researchers in Japan announced.

The results, published in the American Thoracic Society’s the American Journal of Respiratory and Critical Care Medicine in March 2007, were released by Kenji Minoguchi, M.D., Ph.D., of Showa University School of Medicine in Tokyo, and nine associates.

In the study, the researchers looked at silent brain infarction, which is death of the brain tissue caused by a lack of blood supply. The researchers had a group of 50 male patients who had been diagnosed with obstructive sleep apnea (OSA) as the subjects.

The researchers also examined the effects of three months of treatment with nasal continuous positive airway pressure (nCPAP) on serum inflammatory marker levels in 24 male patients who had moderate to severe OSA.

The authors write in the findings that the occurrence of stroke in patients with OSA is likely preceded by subclinical cerebrovascular disease, or silent brain infarction, which is detectable with brain magnetic resonance imaging (MRI). The lesions identified as silent brain infarction were either wedge-shaped or round and showed up in brain white matter on MRI scans.

(pull)nPAP may be an important treatment intervention for decreasing the cerebrovascular risk in this susceptible population. –Dr. Minoguchi(/pull)

“The percentage of silent brain infarction in patients with moderate to severe OSA at 25 percent was higher than that for obese control subjects at 6.7 percent, or even patients with mild OSA who had 7.7 percent,” said Dr. Minoguchi.

The investigators noted that cardiovascular disease is commonly characterized by ongoing inflammatory responses that can enhance platelet activation and increase the prevalence of silent brain infarction.

Platelets are small, colorless, irregular blood cells that promote blood clotting. Two important proteins called soluble C40 ligand and soluble P-selectin are markers of platelet activation and appear to forecast future cerebrovascular events.

The researchers found that use of nasal positive airway pressure (nPAP) devices significantly lowered serum levels of C-reactive protein and the levels of the two platelet-activating proteins, all associated with cerebrovascular disease. The devices, which include continuous positive airway pressure (CPAP) and bi-level positive airway pressure (bi-level PAP or commonly called BiPAP) devices, provide treatment many sleep researchers regard as the “gold standard” in treating obstructive sleep apnea. The devices are designed to eliminate or reduce the number of apneic events — episodes of breathing stoppage lasting at least 10 seconds, but often lasting 90 seconds — are the telltale sign of sleep apnea.

“As a result, nPAP may be an important treatment intervention for decreasing the cerebrovascular risk in this susceptible population of obstructive sleep apnea patients,” said Dr. Minoguchi.

In an editorial on this research in the same issue of the journal, Brian J. Murray, M.D., of Sunnybrook Health Sciences Center and the University of Toronto, Canada, wrote:

“The article by Dr. Minoguchi and colleagues provides further important observations on the association between stroke and obstructive sleep apnea, with significant public health implications. The authors, using brain magnetic resonance imaging, demonstrate that patients with obstructive sleep apnea have a higher incidence of so-called silent brain infarction (i.e., those devoid of obvious clinical symptoms leading to self-detection or identification by physician examination). The well-designed and executed study excluded patients with known risk-factor co-morbidities, thereby establishing the relationship between brain infarcts and obstructive sleep apnea itself. The significance of this finding pertains not only to stroke pathophysiology, but to dementia as well.

“Clinically identified stroke represents the tip of the iceberg in terms of cerebral vascular disease by a least an order of magnitude,” he continued. “Small, but strategically placed lesions in the brain can produce clinically obvious stroke. For example, a lesion of only a few millimeters in diameter that is located in the posterior limb of the inner capsule may leave a patient with devastating hemiplegia (paralysis affecting one side of the body), that would be obvious clinically. The need to prevent these types of strokes from developing is obvious.

“Silent infarction identified on routine neuroimaging studies, on the other hand, may occur in areas of the brain that can only be detected clinically by detailed neurophysical assessment, or perhaps not at all with currently available tests. It is hard to believe, however, that loss of brain tissue should go without consequences. The brain may reorganize functional networks to adapt to lesions and recover function. But with each subsequent stroke, the capacity to do so is diminished. This at least partially accounts for the finding that patients with stroke and obstructive sleep apnea tend to have a longer rehabilitation stay and worse functional recovery than those patients without obstructive sleep apnea.

“Treating obstructive sleep apnea with continuous positive airway pressure appears to reduce the incidence of clinically obvious stroke. This study provides a novel potential mechanism for this finding. In particular, those patients with silent infarcts and sleep apnea had elevated markers of platelet activation, such as soluble CD40 ligand and soluble P-selectin. Furthermore, continuous positive airway pressure therapy for 3 months can lower such markers in this population, thereby providing a link between the white matter lesions and their pathogenesis. Treatment with continuous positive airway pressure may therefore lead to a reduced incidence of subsequent ischemic brain lesions.”

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Sleep … Why Should We Do It?

How Much Do We Need? 

Sleep: it’s a basic necessity of life, as important to our health and well-being as air, food and water. The way we sleep at night has a great impact on our general health as well as our daily mood, behavior, and performance. It also has a huge impact on the overall quality of our lives.

According to recent National Sleep Foundation (NSF) Sleep in America polls, more than one-third of American adults get less than seven hours of sleep weeknights, nearly three-quarters experience a sleep problem a few nights a week or more, and more than one-third is so sleepy during the day it interferes with daily activities. In addition, nearly one-quarter of the adults in this country don’t get even the minimum amount of sleep they say they need to be alert the next day, putting themselves at risk for injury, health, and behavior problems!

In the past century, we have reduced our average time asleep by 20 percent and in the past 25 years, we have added a month to our average annual work/commute time. While our society has changed, our bodies have not. Our national sleep debt is affecting all of us, and we are paying the price.

How much is enough?

Getting enough sleep refers to the amount of sleep you need to not feel sleepy the next day. Adequate sleep is when you awaken naturally without an alarm clock. Quality sleep means it is continuous and uninterrupted.

Sleep requirements vary over the life cycle. Newborns and infants need a lot of sleep and have several periods of sleep throughout a 24-hour period. Naps are important to them as well as to older infants and toddlers who may nap up to the age of five. In adolescence, sleep patterns shift to a later sleep-wake cycle, but teens still need around nine hours of sleep. As we get older, sleep patterns may change, but the need for sleep remains the same. Sleep experts generally recommend an average of seven to nine hours per night for adults; some people can get along with less while others may need more.

You are how you sleep

American adults say that when they don’t sleep enough, they have more negative moods – they are more irritable, stressed, and tired. Studies show that lack of sleep leads to problems completing a task, concentrating, making decisions, and unsafe actions. More recent research ties sleep deprivation to signs of aging and symptoms of diabetes. Certain hormones are released during sleep; when you don’t sleep long enough to allow these hormones to be released, weight gain and lack of fitness can result. Other serious consequences of sleep deprivation include the approximate 100,000 vehicle crashes and 1,500 deaths that occur each year as a result of drowsy driving.

Nature’s biological clocks

Sleep occurs naturally in response to how long we are awake. The need for sleep accumulates, and the longer we are awake, the stronger is the drive to sleep. Our circadian biological clock, located in the brain, regulates when we feel sleepy and when we are alert. It is influenced by light, so we naturally tend to get sleepy when it is dark and be alert when it is light. Body temperature, which lowers throughout the night, and hormones that are secreted during sleep, also play a role with our “clock,” which runs on a 24-hour cycle. This cycle often causes dips in its rhythm resulting in sleepiness around 2:00-4:00 in the morning and 1:00-3:00 in the afternoon.

Sleep stages

There are various states and stages of our sleep that follow a predictable pattern of REM (rapid-eye movement) and NREM (Non-Rapid Eye Movement) sleep throughout a typical eight-hour period. Each of these states alternates every 90 minutes; the time spent in each of these states and stage varies by age.

N-REM: 75 percent of the night

We enter N-REM sleep as we begin to fall asleep; there are four stages:

Stage 1 – Light sleep; between being awake and entering sleep

Stage 2 – Onset of sleep; disengaged with environment; regular breathing and heart rate; body temperature falls.

Stage 3 and Stage 4 – Deepest and most restorative sleep; muscles relaxed; blood pressure drops; breathing slower; energy regained; hormones released for growth and development

REM: 25 percent of the night

Occurs increasingly over later part of night; provides energy to brain and body; brain active and dreams occur as eyes dart back and forth; bodies immobile and relaxed, muscles shut down; breathing and heart rate may be irregular.

Tips for Good Sleep

There are several things you can do to help ensure a good night’s sleep:

• Establish a regular bed time and wake time schedule to help set your body’s internal clock.
• Avoid caffeine and nicotine products close to bedtime.
• Avoid alcohol close to bedtime.
• Exercise regularly but avoid doing so at least three hours before bedtime.
• Establish a regular relaxing, non-alerting bedtime routine.
• Create a sleep-conducive environment that is dark, quiet and cool.

Awake In America works with the National Sleep Foundation (NSF) year-round to help increase awareness about the importance of sleep and the treatment of sleep disorders. For more information, visit the NSF’s Web site or check out Awake In America’s site.

(Adapted from the National Sleep Foundation publication, Let Sleep Work For You!)

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National Sleep Foundation & Awake In America
Announce the Great American Sleep Challenge

PHILADELPHIA (March 1, 2007) – Does having more energy, feeling refreshed and zipping through the day with a rejuvenated spirit sound intriguing or, maybe even impossible? It could be easier to achieve than you think.

One solution may be to get a better night’s sleep. That’s easier said than done, right? Well, there’s help. Continue Reading »

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