New Korean research indicates that regular snoring may double the risk of chronic bronchitis. From earlier research, we already knew that people who suffer from chronic bronchitis are more likely to snore, or have obstructive sleep apnea (OSA).

This prospective study gives us evidence to suspect that the snoring may actually come first, and may play a role in the later development of respiratory problems. The researchers compared snorers and non-snorers, and then followed them for four years to track new cases of chronic bronchitis.

Not only did snoring increase the risk of developing chronic bronchitis, it appeared to do so in a dose-dependent fashion: people who snored 5 nights a week or less were 25 percent more likely to develop chronic bronchitis, but people who snored 6 or 7 nights a week were 68% more likely to contract the disorder.

At this point, the exact mechanism(s) behind this relationship are open to speculation. The researchers themselves say they cannot explain it, although they theorize that the vibrations of snoring may irritate tissues and produce inflammation.

Personally, I imagine that snoring must cause increased negative pressure in the airway. That negative pressure could draw bacteria or other irritants from the nose or mouth down into the lungs.

Or maybe oral breathing (which typically accompanies snoring) could cause the airway to dry out, making it more susceptible to irritation or infection. As we all know, the nose is our body's natural humidifier, but snorers typically breathe through the mouth instead.

Whatever the cause for the link between snoring and bronchitis, this new research underlines the fact that snoring is a significant health symptom, not something that should be routinely ignored.

In a November 2007 interview, Ledger described himself as an insomniac: "Last week, I probably slept an average of two hours a night. I couldn't stop thinking. My body was exhausted, and my mind was still going."

He also admitted to doubling his dosage of Ambien if the first dose proved ineffective.

AOL Entertainment reports that actor Jack Nicholson had warned Ledger against using Ambien. Nicholson says he stopped using the sleeping medication after an episode of sleep-driving: "I took it once and somebody called me in the middle of the night and I woke up in my car 50 yards from my house. I almost drove off a cliff. I didn't know where I was."

Sleepwalking and hallucinations are among Ambien's known side effects. The media is rife with stories about bizarre Ambien behavior, and there was even a class action lawsuit filed in the past. That case was closed, but in 2007, the FDA requested that the makers of all sedative-hypnotic drugs strengthen product warning labels regarding the possibility of "complex sleep-related behaviors" such as sleep-driving and sleep-eating.

In defense of Ambien, many of the accusations against it come from people who used alcohol, or took a variety of medications along with the sleeping pill. (And that certainly seems likely in Ledger's case.) When used properly, it is deemed safe and effective. (Photo:Dima Gavrysh/Associated Press)

Clearly, anyone who uses sedative-hypnotic medications needs to do so under the watchful eye of a qualified physician, and needs to report side effects including unusual behavioral effects. Perhaps Heath Ledger's legacy will be to help teach us that lesson.

How many masks do you have available at your sleep laboratory? Do you try to always get the "latest greatest" masks, or do you stick to mostly "tried and true"? How often do you use a full-face mask instead of a nasal mask?

I got to talking about these issues with a couple of people at the last APSS/AAST meeting, and the exchange got a little heated! People have passionate opinions about this - similar to the divergent passionate opinions I've heard expressed about home sleep testing (HST).

I'll try my best to explain the rationale on both sides of the mask-choices debate. Please feel free to share your opinion.

On the one hand, too many choices may be confusing and overwhelming to the new CPAP user. So perhaps it's a good idea to start with a standard, inexpensive mask (trying to minimize out-of-pocket expenses for the patient.) Then, only if the patient has specific complaints, try an alternate. It can also be cost-prohibitive for the sleep lab to try to stock too wide a variety of masks. Or there may be space limitations that make it impossible. Some DMEs do not carry all masks; patients could be frustrated if they are unable to obtain the same type of mask for home use, as they used at the sleep lab.

On the other hand, the sleep study night is the golden opportunity to impact the patient's long-term compliance with PAP therapy. So maybe it makes sense to experiment to see which mask optimizes things like patient comfort and leak control. Perhaps we do a disservice to our patients, if we use a "one-mask-suits-all" approach. We tweak the CPAP pressure, seeking that one perfect setting that will address our patient's individual need. So why would we treat mask choices any differently? The mask is a critical component of acceptance of CPAP therapy.

So, there are the two sides of the story. Which approach do you use at your lab?

I have a vegan friend who has always distrusted cell phones, and refuses to use one. I used to laugh at this, likening it to my father's early misgivings about microwave ovens. When we got our first microwave in the 1980s (as a gift), Dad would hurry out of the kitchen whenever it was running, eager to protect his body from unbidden assault by the strange waves.

I always thought my vegan friend's mistrust of cell phones was like that, just an overcautious reaction to unfamiliar technology. Eventually, I thought, he'll come around and see that there's nothing to worry about.

But maybe his idea isn't so funny, after all. Recent research funded by the mobile phone industry, and published by Progress in Electromagnetics Research Symposium at the Massachusetts Institute of Technology suggests that cell phones are associated with poorer sleep architecture, as well as other health complaints.

While the study was small (71 participants), its design included a "placebo" type control group - a group of people who thought they were receiving cell phone radiation, but actually got none. The placebo group had shorter sleep latencies and more deep sleep than the radiation group. In addition, the group who received the radiation had more complaints of headaches and confusion than the placebo group.

A couple of weeks ago, my blog addressed the link between electronic devices in the bedroom and daytime sleepiness among teens. This new research is another intriguing piece of that same puzzle. Even if the cell phone doesn't lure kids to stay up past their bedtime, or ring in the middle of the night, maybe its electromagnetic effects could still be destructive to their slumber.

Okay, so maybe my dad and I are more alike than I thought... Because for now, I think I'll ban my cell phone from the bedroom. And use the land line for all my evening conversations. Better safe than sorry, right?

Why do we sleep? This fundamental question has remained a mystery for thousands of years. The precise answer has always eluded us (and is likely to be quite complex). But the more we study this question, the more it seems to me that the bottom line is growth -not just physical growth, but also growth and restructure of our neural networks.

It seems clear that living things need sleep. Fruit flies sleep. Zebrafish sleep. Some flowers and plants appear to sleep. Apparently, even the lowly worm must sleep. At least, that's what new research suggests.

David M Raizen and his colleagues at the University of Pennsylvania School of Medicine studied roundworms and say they go into a period called lethargus, when they are behaviorally quiescent and less responsive to external stimuli.

Interestingly, lethargus occurs at a time when the worms are undergoing neural development, leading the scientists to suspect that sleep may be necessary for neural plasticity. This obviously dovetails nicely with the observation that humans tend to sleep a lot when they are working on neural growth - for example, in early infancy or after brain injury.

Of course we have long known that human growth hormone is released primarily during slow wave sleep, so sleep supports physical growth as well as neural growth. When it's time for physical restructure of their bodies, caterpillars retreat into a slumber-like state within a chrysalis before emerging as butterflies. Human kids who are "still growing" also need extra sleep time.

Recently, Emmanuel Tannenbaum published an article using mathematical models to suggest that organisms must shut down external (incoming) stimuli, in order to effectively process internal (stored) material. He believes we cannot effectively and efficiently work on restructuring ourselves, if we are trying to attend to the distractions of our surrounding environment. Makes sense to me. Multitasking, although a buzzword in management circles, often produces error-ridden results.

In 1986, Marvin L. Minsky wrote, "The principal activities of brains are making changes in themselves." Isn't it fascinating to think that the most important changes - rebuilding our minds from the inside out - may actually be happening while we sleep!

Now that computers can understand our voices, and cars can pinpoint our global position, I guess it was about time for beds to go high-tech as well. The new Starry Night Bed from Leggett and Platt is like something from the Jetsons household.

It detects vibrations of snoring, and automatically raises the head of the bed 7 degrees to compensate for it. It senses your tossing and turning, and tracks trends. Its "Good Morning Screen" reports your sleep stats and offers daily tips on improving sleep quality.

If you don't feel like sleeping, use the pop-up projection screen to watch a DVD, or listen to music on your built-in, surround-sound speakers. Cold? The mattresses have heaters. If you want more detail on the product, check out the video on CNET TV or one of the articles about it on Fox Business or Gizmodo.

The price tag of this wondrous bed ranges from $20K - $50K, depending on which bells and whistles you select. Will people pay that? To put it in perspective, people often spend as much on a nice car, and spend far less time there than they would in bed. (But I'm not sure unconscious time counts the same as conscious time.) The company plans to make its first deliveries of the product in 2009.

Will sleep labs in the future all have smart beds like these? Will next-generation smart beds have a George Jetson pop-you-out-of-bed-like-a-toaster feature? Stay tuned! 

You probably already know that there is a link between poor sleep hygiene and death. If we graphed this relationship, we'd get a "U-shaped" distribution. In other words, if your sleep duration is extreme - either extremely short or extremely long - your mortality risk increases.

In the middle of the graph, there is a "sweet spot", a zone that represents sleeping in moderation (7 to 8 hours each 24-hour day). Here, mortality risk dips to its lowest.

Many factors influence this U-shaped curve, and most scientists agree that one of these factors is diabetes. Research published in December confirmed that the relationship between sleep duration and type 2 diabetes is (what else?) a U-shaped distribution. Short sleepers and long sleepers are both at increased risk.

Why? It certainly appears that altering our sleep length changes our body chemistry. A quote from Science Daily's coverage: "Experimental studies have shown sleep deprivation to decrease glucose tolerance and compromise insulin sensitivity by increasing sympathietic nervous system activity, raising evening cortisol levels and decreasing cerebral glucose utilization. The increased burden on the pancreas from insulin resistance can, over time... lead to type two diabetes."

Now, new research suggests that the "sweet spot" goes beyond sleep length; sleep depth is also important. Restricting slow wave sleep (SWS) is enough to impair glucose tolerance, even when total sleep length is unaffected. Dr. Esra Tasali and colleagues at the University of Chicago recruited healthy, normal weight adults and let them sleep for 8.5 hours on two consecutive baseline nights.

But on the following three nights, the researchers disrupted any observed SWS by playing repetitive tones on bedside speakers, loud enough to cause arousal, but not loud enough to awaken the sleeper. Glucose tolerance dropped by 23%, even though cortisol levels appeared to be unaffected.

If you'd like to read more about the research, there is a nice article about it on MedPages. In the meantime, try to stay in that "sweet spot!"

Do you routinely place a disposable bacterial filter at the far end of each patient's CPAP tubing before connecting hose to machine? From an infection control standpoint, it may be an important question, especially if your lab provides heated humidity during titration.

New research published in the latest issue of the Journal of Clinical Sleep Research simulated a week of CPAP use at 20cmH2O to see whether bacterial contaminants introduced into a humidifier chamber could migrate to the CPAP tubing under varying conditions. When there was no filter, the scientists recovered bacteria from 9 of 11 corrugated CPAP hoses. However, when there was a hydrophobic filter in place, all circuits were free of microorganisms.

Be aware that using a filter use may affect patients' prescriptions. In this study, there appeared to be a small but significant pressure drop accompanying use of a bacterial filter. So if you use a filter at the sleep lab, the patient should also use one at home. As we all know, CPAP therapy can only be effective if the patient can maintain the right treatment conditions at home (pressure level, mask fit, unintended leak, breathing circuitry, etc.)

And there's another good reason why we should be urging CPAP-plus-humidity patients to use bacterial filters at home. We know that many patients do not clean their equipment as often as they should, and many do not follow clinical instructions to the letter (for example, using potentially-contaminated tap water in their units instead of distilled water). Filters might help protect those folks.

One last word - this research was industry sponsored. (Interesting, considering there is an editorial in the same issue of the journal, denouncing industry-sponsored research!)  Obviously, the makers of bacterial filters have a huge financial stake in whether they are used. Nevertheless, I have long championed the use of bacterial filters in the sleep lab, and believe in their importance. What do you think?

I ran across a great article published in the Baltimore Sun (click here to read it), that discusses the link between sleep and obesity.

Research has consistently found a correlation between sleep deprivation and obesity, and has also established a possible biochemical basis for it (changes in blood sugar, and in ghrelin and leptin, which have opposite effects on appetite).

But the "missing link" has always been a (nonexistent) research study that would compare outcomes between dieters who get adequate sleep and those who carry a sleep debt. Thanks to the NIH, that research is now underway in Maryland. We should have preliminary results in July 2008. (I'll keep you posted.)

By the way, this link between sleep deprivation and obesity applies to kids as well as adults. A new study from New Zealand (click here for news story) links sleep deprivation with both obesity and behavioral problems. It is slated for publication in the January 1 issue of the journal SLEEP.

Exciting new primate research, published in the December 26, 2007 issue of the Journal of Neuroscience suggests that a quick whiff of orexin-A can correct many of the cognitive deficits caused by sleep deprivation.

Prior research had already shown that orexin (hypocretin) was linked to arousal, and dysfunctions of it can cause sleep disorders such as narcolepsy and insomnia. What's new about this study is its finding that intranasal delivery of the orexin-A is much more effective than intravenous delivery.

While both routes of administration were effective, a low dose of orexin-A delivered via nasal spray, was more effective than the highest dose of orexin-A delivered via injection. "High load" cognitive tasks showed the most dramatic improvement.

This research obviously has enormous implications for the development of pharmaceutical products to promote alertness.

A lot of teenagers will be receiving electronic gifts this holiday season: cell phones, iPods, computers, etc. But if they use them in the evening in their bedrooms, they may fall victim to "junk sleep" - sleep whose quality and quantity are not adequate to sustain good health. The term "junk sleep" (coined earlier this year) is a powerful educational tool we techs can use when educating teens and parents about adolescent sleep issues.

Research released earlier this year by Britan's Sleep Council, and similar research released in 2006 by the National Sleep Foundation, suggests that almost all teens have electronic gadgetry in their bedrooms. Those who have four or more devices are twice as likely to fall asleep in class or while doing homework.

These buzzing, blipping, illuminated items disrupt sleep in many ways. Their "fun factor" lures teens to sacrifice sleep, and their lights and sounds cause nocturnal arousals. (How many of us have been running a sleep test and suddenly heard a cell phone, tucked away in the patient's belongings, blare in the middle of the night?)

For students, avoiding sleep deprivation is essential, because it clearly interferes with learning and memory. Robert Stickgold's group at Harvard has shown that sleep deprivation shifts so many precious mental resources toward maintaining altertness, that there simply isn't enough brain power left over to store new information.

What can we do about "junk sleep"? The electronics industry is starting to ponder technological solutions. In the meantime, parents and sleep educators can urge teens to ban electronics from the bedroom, to encourage healthier sleep patterns and promote academic success and automobile safety. (The National Sleep Foundation has some great anti-drowsy-driving Public Service Announcements geared toward teens and young adults: click here and here to download them.)

On December 14, 2007, Medicare released a DRAFT of a new position statement on home testing. Click here to read it. Medicare is collecting public comment for 30 days, and plans to finalize the new policy by March 2008.

The good news: the new document suggests repealing the pesky "2-hours-of-sleep" rule that often hinders severely-sleep-disordered patients from qualifying for split studies. Under the newly-proposed guidelines, we could simply count the number of events until we reached Medicare's criteria values:

"For example, a patient who has at least 15 recorded events per hour over a two hour period would have had at least 30 recorded events. Thus, while we no longer believe two continuous hours of recorded sleep are always necessary, we will continue to require that the total number of events needed for a positive test to be that which would need to occur over two hours to arrive at the specified rates in the current NCD. That is, recording of at least 30 events for patients without comorbidities and at least 10 events for patients with comorbidities is required for the computation of events per hour."

More controversial, Medicare is proposing that multi-channel home testing and one-channel screeners (just oximetry or airflow) would be acceptable alternatives to full, in-lab sleep testing for the diagnosis of sleep apnea. In their opinion, there is no "true gold standard" for sleep testing: "There is no anatomic or physiologic "gold standard" for the diagnosis of obstructive sleep apnea, in contrast to conditions such as cancer where a tissue biopsy result is the definitive standard reference." So when home study and in-lab data conflict, no way to determine which is more accurate. (This is confusing to me, since it seems pretty well-established that esophageal pressure monitoring would be an actual gold standard method for evaluating obstructed breathing...)

Medicare even considered doing away with diagnostic sleep testing entirely, and allowing patients to be placed on CPAP therapy for 12 weeks based on clinical symptoms alone, but came to the conclusion that: "We do not believe that this evidence is currently sufficient..." to support CPAP prescriptions without prior diagnostic testing. However, Medicare supports clinical trials of this system, and appears to intend to reimburse in that context. Medicare is particularly interested in any evidence for harm from CPAP applied in this scenario.

They also propose to require a 12-week trial of CPAP, and subsequent proof of its benefit to the patient, in order to continue coverage for the therapy.

If you are planning to submit comments, be aware that Medicare is not as interested in opinions as new research evidence. So if your sleep lab has done relevant research (that is not already cited in Medicare's position statement), that would be the best kind of commentary to submit.

The AASM has, for many years, taken a strong stance against home sleep testing and other forms of portable monitoring. But other medical groups have been steadily lobbying for Medicare acceptance of it.

On December 15, 2007, the AASM revised its stance, publishing new clinical guidelines that permit portable monitoring...under very narrow conditions. The newly-published rules restrict its use to accredited laboratories, require involvement of a sleep-boarded physician, and limit application to certain populations. Technically, the same sensors must be used for portable monitoring as for in-lab monitoring.

As it turns out, the AASM's position on portable monitoring has not actually changed very much. The important shift is the way they are categorizing themselves; formerly "opposed" and now "cautiously accepting."

On the PRO side, portable monitoring would certainly increase access to sleep diagnostic services. Consider nursing home residents and other health facility inpatients, notoriously difficult to serve via traditional in-lab sleep testing. The most powerful evidence in favor of portable monitoring is the Sleep Heart Health Study, a rigorously-controlled research initiative that successfully used home-testing methodology.

On the CON side, portable monitoring has a huge potential for misuse. The big fear is that underqualified physicians will run a quick home study, make a rapid, respiratory-only diagnosis (missing possible contribution of other sleep pathologies), and then slap a self-titrating PAP device on the patient and call it a done deal. Many patients might be misdiagnosed, and it could be difficult to explain to patients, why they need further testing if they have already had "a sleep study".

What do you think about portable monitoring and home testing?