The Most Common Sleep Disorder at Sleep Medical Centers

There are many types of sleep disorders, and the single most common one might simply be the lack of sleep, but few patients seek treatment at a sleep center for self-imposed or schedule-related sleep deprivation except for the circumstances of a shift worker who is trying to find a way to adapt. Circadian rhythm disorders, however, are not the most common condition treated at sleep centers.

Some would suspect insomnia or its close relative nonrestorative sleep, because it seems like such an obvious condition to motivate someone to find answers. In actuality the overwhelming majority of insomniacs or nonrestorative sleep sufferers never set foot inside a sleep center. Rather, they frequent liquor stores or drugstores from which they often find very useful solutions to their unwanted bouts of sleeplessness. Over the counter drugs and alcoholic beverages are quite possibly the most common treatments currently used by any group of insomniacs or those suffering nonrestorative sleep, regardless of the cause of the problem. Still, most sleep centers do not find a majority of their patients presenting with the complaint of insomnia, but they will see many more patients reporting poor sleep quality compared to reports of insomnia, so combined they might represent more than 50% of a sleep center population.

Our goal here is not just to determine what is the single most common disorder on presentation, but rather what is the final diagnosis that represents the most common condition to be treated at a sleep center. This point of course brings us to sleep apnea, which may have been everyone’s first guess, because sleep centers are clearly designed to test sleep apnea patients and treat them with PAP therapy. With all the testing that occurs in a sleep lab and all the referrals sleep centers receive from primary physicians or cardiologists (who are the docs sending the largest proportion of patients for care), it would seem sleep apnea is the number one problem addressed at final diagnosis.

Now, if we make a distinction between garden-variety sleep apnea versus sleep apnea patients with other co-morbidities, we soon realize that the classic form of sleep apnea is actually not that common, despite what many sleep centers might promote in their view of the field of sleep medicine. And, ironically or not, many sleep researchers and many sleep experts working at leading sleep institutions do not seem to recognize that sleep apnea with co-morbidities is more common than classic sleep apnea.

In fact, the most common form of sleep apnea presentation is with co-morbidities, and among these co-morbidities, there is a particular sleep disorder that often presents more than any other co-occurring medical illness. And, no surprise to you if you have read some of the prior posts, the most common co-occurring condition is insomnia in patients presenting with sleep apnea. Most importantly when insomnia and sleep apnea co-occur together, it truly is a double whammy that requires much more expertise and effort to help these patients. 

The co-morbidity of insomnia and sleep apnea as the most common condition treated and managed at a sleep center is important to recognize, because... (wait for it, as they say on all the blogs) this co-morbidity is not recognized as such! In other words the division in perceptions between those who tend to see only the sleep apnea in their patients and those who see only the insomnia continues to create a virtual wall that blocks recognition and awareness of both conditions occurring side-by-side in the same patient.

Think of it this way: if you went to a sleep center with little or no interest in the problem of insomnia, then at that center, your evaluation and treatment would all be focused on sleep apnea, and at best you might hear about sleep hygiene and sleeping pills but not necessarily in a well-developed plan of education to help you. Whereas, if you went to a sleep clinic operated from the perspective of a psychology center, then the questions and concerns that might be raised about sleep apnea would be far less than the issues discussed regarding your insomnia.

Those of us who research in this area would like to see these perspectives broaden so that the doctor who sees the sleep apnea patient ponders the importance of the co-occurring insomnia and likewise, the psychologist who sees the insomniac ponders the importance of the co-occurring sleep apnea. This point might seem ridiculously obvious to you, but it is unbelievably common to visit a sleep center whether it’s either one or the other, depending upon the background and experience of the sleep physicians.

Naturally, in most sleep centers the imbalance weighs toward too much attention to the sleep apnea. Still, in other types of clinics such as psychology or mental health-oriented ones and even in behavioral sleep medicine clinics, there frequently arises an imbalance with too much attention on insomnia without giving sleep apnea symptoms their due.

There is no easy solution to this problem, because many professionals in all areas of study and practice tend to develop entrenched views about what they first learn. It is for this exact reason, that it is so difficult to publish research papers on this topic of co-occurring insomnia and sleep apnea, because it requires sleep experts who review the research papers to be willing and capable of recognizing the high frequency of this co-morbidity. Once recognized, reviewers will see such research as more clinically relevant. When more papers are published, then more sleep doctors change their practices to accommodate more patients with the co-morbidity.

It is worth closing by saying this process takes time, often quite a lot of time, usually measured in years or decades.

Barry Krakow MD


Dr Krakow’s 27 years of sleep research have focused on the complex relationship between physiological and psychological sleep disorders. Dr Krakow currently operates private sleep medical center, Maimonides Sleep Arts & Sciences, Ltd., and serves as Classic SleepCare’s paid Medical Director.


Barry Krakow MD
Barry Krakow MD

May 18, 2016

Dear LH,

Thank you for your comment.

Sleep quality is judged by a number of factors such as how well sleep is consolidated overall, the depth of sleep as measured most notably by stages of NREM Stage 3 and REM, and in some cases the duration of sleep in the event an individual is intentionally sleep on a shorter sleep cycle due to extenuating circumstances.

For your specific question on lack of Stage 3 NREM (N3) on CPAP, you should definitely discuss the problem with your sleep doctor. Some common issues seen with a lack of this deeper, restorative sleep are specific medication side-effects, poor response to CPAP therapy requiring a switch to more advanced PAP technology such as ABPAP or ASV, and other medical or psychiatric illnesses that interfere with sleep.

L.H. [name redacted by moderator]
L.H. [name redacted by moderator]

May 05, 2016

I am thankful for the depth and frequency of your articles. Your observation in this article is very interesting—I do not have apnea and my sleep doc says he sees someone like me once every 8 years! My question: If you have no N3 sleep, is this the basis of poor sleep quality and does an APAP machine help with this? Excerpt from my sleep study:

Sleep architecture: Sleep latency was 12 min. with sleep efficiency of 63.14%. Slept 4 hours and 7.5 min. in a 6-hour 32 min recording time. 33.7% wake time with 10.5% N1 sleep and 76.6% N2 sleep. N3 sleep was absent with 12.9% REM sleep and a REM latency of 220.5 min.

Ventilatory: 1 central apnea with 6 obstructive hypopnea for an AHI of 1.70. Intercostal effort was normal. There were desaturations without sleep disordered breathing from 82% through 89% for 6.77 minutes of total sleep time. Intercostal effort was normal and no snoring.

Non-ventilatory: 5 periodic limb movements of which one aroused her for an arousal plus wake index of .2. Frequent PVCs with a run of trigeminy occurred with a sleeping heart rate between 58 and 106 beats per minute.

60, 5’11”, 155, retired, swim 2 miles 3x week, some early-eve wine, no cigs, meds or snoring. Life is great except for never feeling rested; can never nap except when watching TV of course!

For 15 years, I had trouble getting to sleep and/or not being able to stay asleep, leading to maybe 4 hours of interrupted sleep. I studied your book several times since 6/2015. After many changes (imagery, meditation, puzzles, Nasalcrom, lower A/C, etc), I was getting 5 hours of interrupted sleep. But still tired. I finally had a sleep study (terrible night—too hot, bed too hard, anxious) in 3/2016. Was told I could take 10mg ambien for my overnight study and I did. I did not qualify for apnea. Doc then let me borrow an APAP. I am getting 6 hours, mostly uninterrupted and feel better! He said I can buy the machine (at 6 pressure), try oral device, try Theravent or do nothing. I’d prefer the latter of course… As you warn, he is focussed on apneas, and he is very rushed and didn’t have time for questions about my sleep quality.

I did Sleepyhead my APAP data and have more stats—none of which were found worth discussing by my doc, [name redacted by moderator].

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