Gaps in Sleep Medical Knowledge: Part I (Normal Sleep)

Sometimes, it proves very useful to look at what we do not know in a particular field of medicine. In this case, we shall look at sleep medicine and attempt to raise both questions and answers on what seems to be missing from the field. While a minor objective of this discussion will likely be seen as criticism of various components or institutions of the field, the greater goal is to organize thinking and ideas that might lead to greater innovation in sleep medicine for the betterment of our patients as well to create more opportunities for sleep medicine professionals. In some instances, we will delve into gaps of knowledge in the field; and, we will also look at certain strategies or tactics currently missing from the field, which if implemented might create more precision in clinical care and more expediency in managing clinical care.

Normal Sleep. It remains a puzzling feature of sleep medicine that no codified definition of normal sleep has been determined. Highlighting this problem is the consensus paper recently published describing a set minimum number of hours of sleep for which one should strive. But, this sort of research only speaks to the concept of sleep quantity and thus does not address the two underlying constructs of sleep continuity and sleep quality, both of which are fundamentally more important than hours of sleep, because the combination of continuity and quality ultimately determine the number of hours of sleep for the vast proportion of humanity, regardless of whether or not they would classify themselves as so-called normal sleepers or as sleep disorder patients.

It is plausible and likely that the emphasis on sleep quantity fits well into superficial media narratives attempting to alert the public on safety and other interesting issues about sleep. However, it is equally plausible and likely many sleep professionals and sleep institutions just do not have the curiosity, motivation, or interest to move beyond the sanctification of the number of hours of sleep into public consciousness as they apparently hope such information will add legitimacy to the field of sleep medicine. I cannot argue such an approach will not achieve its effect, but I can argue it is a notably incomplete and potentially hazardous way of communicating to the public about the nature of sleep.

As we recently discussed how Medicare compliance rules steer some people to think they only need to use their PAP devices 4 hours per night for only 5 nights per week, this consensus on the minimum number of 7 hours per night is sure to diffuse into society and follow the laws of unintended consequences. Undoubtedly, we will soon hear stories, whether in our encounters with sleep patients, or in primary care doctors’ encounters with their patients, or in the media, regarding people led astray by this consensus and how it adversely affected their lives when they inappropriately decreased their total sleep time from 8 or 9 hours per night down to 7. This type of conforming behavior is ubiquitous among humans and expands exponentially in the modern age of Too Much Information.

As described in great depth in my book Sound Sleep, Sound Mind, the quality of slumber must first be evaluated and “treated” in anyone who wants to figure out the number of hours of sleep needed. It is impossible to prescribe a set number of hours to anyone who is currently laboring under the conditions and circumstances of clear-cut sleep disorder symptoms, not to mention the vast numbers of individuals in society who do not even recognize these symptoms.  

If research were conducted instead to determine all the essential parameters of normal sleep, and we established a cohort of people who met these parameters, then we could collect truly normative data to establish how many hours of sleep are needed among these individuals. These data would provide a genuine benchmark to answer the question: how many hours of sleep do normal sleepers need? By not having conducted this research, a glaring hole remains in the field of sleep medicine, one which will never be filled by consensus statements on minimum numbers of hours to sleep.

As a starting point, there needs to be a very thorough discussion on what normal daytime as well as night time behavior would constitute based on a normal period of sleep followed by a normal period waking activity. When we interviewed individuals who allegedly were normal sleepers, some of the hallmark findings included:

  1. Rare awakenings at night, but when awakened rapid return to sleep in seconds
  2. No breathing or movement symptoms to suggest underlying physiological disorders
  3. No trips to the bathroom at night
  4. Felt very refreshed in the morning after the sleep period
  5. Most described being alert and energetic fairly soon after awakening, albeit a few reported sleep inertia for which caffeine was rarely required to reverse
  6. Rare use of any caffeinated beverages and even rarer use of such drinks as stimulants.
  7. Rare or no napping behavior whatsoever.
  8. Remarkably consistent energy level with minor dips occasionally during the day.
  9. Remarkable absence of fatigue symptoms unless directly related to a post-exertional period
  10. Remarkable absence of sleepiness symptoms or only minimal drowsiness that resolves spontaneously in a few minutes or with simple behavioral activation such as talking to someone or engaging in a household or work task.
  11. A moderate to strong urge for physical activity or exercise on a daily basis, very distinct from making a commitment to go to the gym for health purposes. Rather, a strong desire to experience physical activity or exercise as a regular daily behavior.
  12. A surprisingly strong energy reserve during evening hours to conduct volunteer, social, parental or other active work or play such that the individual tends to naturally avoid engaging in passive activities such as television. Computer games might be an exception to this rule, as research indicates gaming is an active not a passive enterprise.
  13. Last, a clear understanding of the difference between feelings of tiredness and sleepiness, which yields a natural ability to get into bed at night and go to sleep with or without a routine schedule.

I must add the above findings are not scientifically validated research. It reflects discussions we have had with approximately 30 adults, men and women, who described themselves as normal sleepers and who fit essentially all of the above criteria. We have met considerably more individuals who alleged they were normal sleepers yet who by self-report not only could not affirm many of the above criteria regarding their own lifestyles, but also eventually were diagnosed with physiological sleep disorders.

Without a working definition of normal sleep, which to reiterate may or may not relate to the number of hours of sleep, we cannot communicate accurately with our patients about their sleep issues, and we cannot communicate consistently with our fellow sleep professionals. For now, scant research is being conducted on this concept, and the research broaching this topic is often confounded by a lack of strict criteria to attempt to define normal sleep. This gap in knowledge reflects a sizeable void in the field of sleep medicine.


Read more from this series:

Gaps in Sleep Medical Knowledge: Part I (Normal Sleep)
Gaps in Sleep Medical Knowledge: Part II (Normal Breathing)
Gaps in Sleep Medical Knowledge: Part III (The Medicare Hypopnea Scoring Maze)
Gaps in Sleep Medical Knowledge: Part IV (The Unsolved Puzzle of UARS)
Gaps in Sleep Medical Knowledge: Part V (Coding Issues for Billing and Reimbursement)
Gaps in Sleep Medical Knowledge: Part VI (Prior Authorizations and Atypical Patients)
Gaps in Sleep Medical Knowledge: Part VII (Confusing Compliance with Outcomes)
Gaps in Sleep Medical Knowledge: Part VIII (Comorbid Sleep Disorders)
Gaps in Sleep Medical Knowledge: Part IX (Miscellaneous Topics)


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.

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