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Regular, heavy snoring is the most noticeable feature of sleep-disordered breathing, and is itself associated with hypertension, strokes, and heart disease. Several epidemiological studies of snoring to date have yet to take in a large, representative population sample. In this study, the target population included all residents of the United Kingdom over 15 years of age and not institutionalized, over 45 million people, from which a representative sample of 4,972 subjects was selected for telephone interview. Cooperation was obtained from 80% of the subjects who were approached. The interview was computer-directed and adjusted according to prior answers of the individual. Criteria for identification of sleep disorders were drawn from the 1990 version of the International Classification of Sleep Disorders, except for polysomnographic monitoring. Regular snoring was reported by 40% of the population, men more often (48%) than women (34%). Snoring increased with age, from least often in the 15-24 year age group (23%) to most in the 45-54 age group (54%), thereafter declining to 37% in the age group over 65. Breathing pauses during sleep, much less frequent than snoring, were reported by 4% overall, showing a similar age distribution to snoring but with a maximum of 5% in the 55-64 year age group. Again, women were less often affected than men. Snoring was associated with obesity, daytime sleepiness, napping, nighttime awakenings, high caffeine intake, and smoking. Breathing pauses were associated with taking antianxiety medications, having a diagnosis of obstructive airway disease or thyroid disease, and consulting a doctor at least once in the past year. The coexistence of both snoring and breathing pauses in the same individual (reported by 2.5%) was associated with obesity, male sex, leg pain, difficulty staying asleep, not sleeping in a fully supine position, having urinary problems, high blood pressure, daytime sleepiness, and high caffeine intake. Applying to this data the first three International Classification of Sleep Disorders criteria (i.e., omitting polysomnographic findings) for the diagnosis of obstructive sleep apnea syndrome, the authors found this diagnosis associated with obesity, male sex, difficuty maintaining sleep, daytime sleepiness, high blood pressure, leg pain, and non-restorative sleep. These criteria yielded a prevalence of OSAS of 2% in the sample as a whole, 1.5% in middle-aged women and 3.5% in middle-aged men. Nevertheless, only 18% of subjects with breathing pauses and 9% of snorers believed they had a sleep problem. Reports of falling asleep at the wheel were more frequent among subjects with breathing pauses (6.2%) and snoring (4.3%) than among the rest of the sample (2.4%); but actual accidents, which occurred among 5.3% of drivers during the preceding year, showed no significant differences between groups. Subjects with breathing pauses--but not snorers--more often consulted a doctor at least once in the previous year (81% vs. 61% for those without breathing pauses). Medical help was sought six or more times by 31% of those with breathing pauses vs. 12% of those without. There was a trend to increased number of hospital admissions among those with breathing pauses (19%) compared to those without (11%). Hypertension was more frequent in those with breathing pauses (14%) than in snorers (9%) or others (6%). Treatment for other physical illnesses was more frequent among those with breathing pauses (40%) than in snorers (17%) and others (14%). The authors considered this to be the first study of its type with such a large, representative sample of the general populaton. Their results confirmed the expected associations of sleep-disordered breathing with obesity, hypertension, disrupted nocturnal sleep, non-restorative sleep, daytime sleepiness, greater use of caffeinated beverages, and drowsiness while driving. What the authors found surprising was that patients often labelled their problem of "daytime sleepiness" as "insomnia." The use of the insomnia label was thought to interfere with recognition of sleep disordered breathing and to explain the higher use of anti-anxiety drugs, ordinarily contraindicated among these patients. They noted that their overall prevalence figures were much higher than in a 1990 survey in England, which probably identified only the most severely affected patients, but their results were consistent with rates in one recent American study and another done in Iceland. Their results were taken to suggest that sleep apnea is still widely unrecognized in Britain.

Personally, I don't believe that mere questionnaires can determine the population prevalence of OSAS, any more than I believe that laboratory tests in the absence of clinical history can make this diagnosis, as I said in critiquing another article. Rather, I believe that subjective, symptomatic and historical data must be complemented by large-scale screening with polysomnography or some modified version thereof. I feel this is necessary to identify not only false positives but also a significant number of false negatives from questionnaire diagnoses alone. Many would consider it obvious that adding another set of requisite criteria (i.e., polysomnographic data) to the diagnostic process would eliminate some subjects qualifying for diagnoses on the basis of questionnaire data alone, but many might find it far from obvious that obtaining such polysomnographic data could also increase the number of patients qualifying for diagnoses. However, I emphasize the unusual, incidental manner the usually terse International Classification of Sleep Disorders assumes in modifying its primary ("A") criterion for diagnosis of OSAS: "A. The patient has a complaint of excessive sleepiness or insomnia. Occasionally the patient may be unaware of clinical features that are observed by others." The second sentence may, and probably does, also refer to secondary symptomatic criteria under heading "B" (frequent episodes of obstructed breathing during sleep); and "C" (loud snoring), but it is specifically appended to the statement of the "primary" symptoms of the disorder--which are hypersomnolence or, interestingly enough, insomnia. Furthermore, one might well ask how "others" (presumably the bed partners) would ascertain the presence of insomnia if the patient failed to recognize it. And while snoring has a way of bringing itself to the attention of anyone in hearing range, it isn't nearly so clear that breathing pauses will come to the attention of "others," especially if they occur briefly and late in the night. The authors noted that about 8% of their subjects lacked bed partners, and even for those that had such partners, I question our assumption that "insomnia" or breathing pauses would usually be apparent to them. This alone might be the basis for some false negative diagnoses. As for the subject/patients themselves, it is becoming clearer from research, as with driving accidents, that denial of sleepiness is quite prevalent. Even more problematic is confusion in the patient's mind about what these terms mean, as exemplified by the substitution of "insomnia" for "excessive sleepiness." How does this confusion arise? I suggest that people gather ample experience of sleepiness resulting from not getting enough sleep; this may lead them to equate the two. It is becoming clear that, even with laboratory tests like the MSLT, we do not have good enough measures of sleepiness that we can be assured it is a single, unitary variable well within our grasp. Why should such an issue exist? Why wouldn't people be well aware if they were excessively drowsy, or unable to sleep? The problem is a generic one: how people learn to identify internal states which aren't objectively observable to others. I can teach a child the meaning of "red" by pointing to objects that are red and objects that aren't red. But I can only teach him the meaning of "sleepy" by observing his eyelids drooping, his head nodding, his slow responses, and by realizing that it is past his bedtime. On the other hand, the same signs might arise if he were instead sick, or sedated. In my own experience, the overpowering "sleepiness" that I associate with my sleep disorder isn't quite the same as the sleepiness one experiences at the end of a long day. For one thing, it comes on rather suddenly, within a matter of minutes, out of a state of seeming alertness. Often it has a "trance-like" quality, where I might sit staring at my computer, immobilized, lacking even the energy to retire to my bedroom down the hall. My eyelids droop, but if I am in a setting (like a meeting) where I must keep them open, I may start to see double--something that I can't remember happening in the days when I mainly got sleepy staying up into the early hours of the morning to prepare for an exam. I usually don't say anything, but if I have to, my speech may sound slurred. Nevertheless, I usually don't feel much concern. In other words, judgment is impaired. There are similarities to a drugged state, but I wouldn't want to call it that! I call it sleepiness partly because I know that the only immediate cure for it is to take a nap, and partly because I know no other good word to describe it that others would understand.     Like a lot of sleep apneics, I used to assume it resulted from not getting enough sleep the night before; therefore I unwisely took sleeping pills for my supposed "insomnia." If a physician and psychiatrist like myself, supposedly expert in identifying and interpreting internal states of mind, can get confused over such issues, how much clarity can we expect from the general public, to whom it isn't even clear they have a sleep-related problem? I submit that sleep apnea--and other sleep disorders--are peculiar conditions, not to be accurately equated with the state of sleepiness people ordinarily encounter after staying up late to study or working a long day, and not best identified by questioning them about internal states they may have no exact words for. Another point to remember is that napping, by itself, is not necessarily pathological, and when we ask a subject to identify "excessive sleepiness" he may have no reason to know that his frequency or duration of napping is "excessive," compared to others. Indeed, many "sleep experts" might have to turn to their textbooks to determine how much the "normal" person naps. Is it "excessive" to feel drowsy at a boring meeting, a tedious lecture, an uninteresting conversation, a bad movie, a long drive? Just as depressed people are inclined to develop "explanations" for their depression in terms of stresses and losses--which may be no more or even less than what many nondepressed people undergo; so may the "excessively sleepy" person evade the label of illness by explaining his sleepiness as "natural" considering boredom, the long day, his allergies, the weather, whatever comes to mind. This has probably been an excessive discourse on a subject which I, as a former psychiatrist, came to feel strongly about: that we cannot rely on the patient's sole self-report. Lacking laboratory tests of much value in psychiatric diagnosis, I would often insist that the patient come to appointments accompanied by a relative, whom I would question closely, probing for inconsistencies (and often finding them). In sleep medicine, where we are fortunate enough to have a "gold standard" of laboratory diagnosis close to the actual pathophysiology of the disease, we shouldn't presume to get by without that measure in making our diagnoses, as cumbersome as it may be. In short, I believe in the truth of the authors' conclusion that the prevalence of sleep-related breathing disorders is underestimated in their country; but I suspect that it is also underestimated in their own study as well.

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