Eight Hours No More:
It’s Time To Change The Recommendations On Sleep Duration for Healthy Adults
Once upon a time, sleeplessness was worn as a badge of honor, a testament to one’s productivity and resilience. Executives flaunted their mere four hours of nightly rest, while biohackers experimented with polyphasic sleep schedules, boasting of heightened cognitive function.
Fortunately, times have changed. Thanks to the tireless efforts of individuals like Dr. William Dement, Dr. Matt Walker, and Ariana Huffington, alongside esteemed institutions such as the American Academy of Sleep Medicine (AASM)and the National Sleep Foundation (NSF), the importance of proper sleep has finally hit home for most Americans. We’ve learned that skimping on sleep not only impairs our short-term performance but also sets us up for a host of long-term health issues, from cognitive decline to metabolic disorders. Yet, in our quest for more sleep, have we inadvertently worsened our sleep?
As a sleep medicine physician, I owe a debt of gratitude to those who came before me, particularly Dr. William Dement, whose book, The Promise of Sleep, opened my eyes to the perils of sleep deprivation. It was a personal epiphany — I discovered that prioritizing sleep over late-night cramming actually boosted my academic performance. From there, I delved into the intricacies of sleep science, conducting research in a sleep laboratory studying sleep deprivation and advocating for increased sleep for residents during my medical training.
But here’s the twist: the more I learned about the detrimental effects of insufficient sleep, the harder it became for me to get a good night’s rest myself. I found myself fretting over every disrupted slumber, anxiously avoiding anything I thought might disturb my sleep. I meticulously dimmed the lights and shunned screens before bedtime and reset my alarm to later after a particularly bad night, hoping to eek out as many minutes of sleep as possible. Eventually, after completing my training in behavioral sleep medicine, I realized that I had become a casualty of well-intentioned but misguided public health messaging around sleep. Yes, sleep is crucial, but the definition of “sufficient sleep” isn’t as clear-cut as we’ve been led to believe.
In the realm of sleep pop science, the gospel of eight hours reigns supreme. According to the AASM and the NSF, adults should aim for a solid seven to nine hours of shut-eye each night to safeguard their health. Matthew Walker, in his acclaimed book “Why We Sleep,” implies that even seven hours may not be enough and warns of dire consequences for those who fall short of the eight-hour mark.
Unfortunately, the notion that healthy adults require a minimum of seven or eight hours of nightly sleep is fundamentally flawed. Upon reviewing the literature, it becomes evident that the risk of adverse health consequences does not substantially escalate until an individual experiences less than 6 hours of sleep opportunity per night.
Delving further into the annals of sleep research, we find that the genesis of the eight-hour mandate lies in studies conducted on a rather specific demographic: young, bright-eyed college students. These early studies extolled the virtues of sleep extension, showcasing improved academic and athletic performance alongside enhanced mood — all achievable with a nightly stint of eight to nine hours in bed. However, a critical caveat emerges: these studies were conducted on a select cohort of young adults, a demographic far removed from the broader adult populace.
Compounding the issue is the nebulous definition of “sleep” itself. Before the advent of consumer sleep trackers, sleep duration was often self-reported or crudely estimated based on bedtime and wake-up times. These methods, while convenient, fail to capture the nuances of sleep architecture, overlooking the fact that short bouts of wakefulness are a normal part of sleep. Contrary to popular belief, healthy individuals spend a significant portion of the night in a state of wakefulness — 10% on average for young adults, rising to 20% or more in older cohorts.
Enter the era of wearable sleep trackers — Fitbit, Garmin, Oura, Apple Watch — promising objective insights into our nocturnal habits. These devices, while not without flaws, offer a more granular view of our sleep patterns. Yet, their rise brings new challenges, shifting the focus from subjective perceptions of sleep to quantifiable metrics. A healthy 50-year-old man who is in bed from 11PM to 6AM would have previously reported that he slept “7 hours”, leading him to believe that his sleep duration is sufficient. His sleep tracker, however paints a different picture, suggesting a mere 5.95 hours of actual slumber assuming he has a normal sleep efficiency of 85%. This disparity between self-reported sleep duration and wearable reported total sleep time challenges our preconceived notions of adequate sleep.
Another aspect contributing to the fallacy of the eight-hour sleep doctrine is the considerable diversity in sleep requirements between individuals. Sleep patterns, like all other human traits, exhibit a spectrum of variability within the population, meaning what constitutes sufficient sleep for one person may not be the same for another. Sleep patterns also change with age with total time in bed remaining relatively stable after age 30 while total sleep time continues to decline throughout the lifespan.
Moreover, the amount of sleep our brain generates on any given night fluctuates based on numerous environmental and physiological factors. Factors such as menstrual phase, exercise duration and type, season, time spent outdoors, moon phase, social connectedness, sense of purpose, stress levels, and overall happiness have all been demonstrated to influence nightly sleep duration. For instance, contemporary hunter-gatherers sleep approximately one hour longer during winter than in summer and 90 minutes less on the full moon compared to the new moon. So how much sleep do we “need”? It is variable and contingent upon a multitude of factors.
But perhaps the most damning indictment of the eight-hour myth lies in its contribution to a burgeoning epidemic: insomnia. Many of my patients, plagued by anxiety over falling short of the elusive eight-hour benchmark, resort to desperate measures in pursuit of sleep. From prescription medications to cannabis and other expensive herbal supplements, the quest for rest becomes an exercise in futility, perpetuating a cycle of sleeplessness.
Ultimately, sleep is an unconscious process we cannot control. Our duration and quality of sleep on any given night is orchestrated by a complex interplay of genetics, age, recent and cumulative sleep patterns, an array of external variables and our emotional state and level of sympathetic nervous system activation. Our sphere of control, if we are fortunate, extends primarily to our wake-up time and the moment we extinguish the lights each evening. With practice we can sometimes learn to calm our sympathetic nervous system at night. Some nights, the sleep we attain aligns harmoniously with the opportunity we afford ourselves, fostering the impression that we’ve enjoyed an uninterrupted night’s rest. Conversely, there are occasions when our sleep opportunity falls short or we give ourself too much time in bed and the night is punctuated by extended periods of wakefulness. Such variability in quality and quantity is perfectly normal and what matters is how we sleep on average over the week, over the month and over the year.
The moment has arrived for a shift in the narrative crafted by the American Academy of Sleep Medicine and prominent voices in the realm of sleep advocacy. We must eliminate the recommendations for a specific amount of sleep that healthy adults “should” obtain and instead spread the message that normal sleep is variable in duration both between and within individuals. What matters are healthy sleep habits such as keeping a regular rise time and allowing for a bit of down time before bed as well as healthy daytime habits such as getting outdoors, eating lots of plants, managing anxiety and stress, exercising and finding social connection. We should continue to advocate for sufficient rest time to employers and schools and explain that some individuals may need 9 hours or more of sleep opportunity to function at their best. Let us bid farewell to the tyranny of the eight-hour myth and forge ahead with a more nuanced understanding of sleep.
ABOUT THE AUTHOR:
Dr. Michelle Jonelis is the founder and medical director of Lifestyle Sleep, a lifestyle-focused sleep medicine clinic in the San Francisco Bay Area. Michelle is board certified in sleep and lifestyle medicine with additional training in behavioral sleep medicine. Her clinical focus is on the non-pharmacologic management of sleep disorders using techniques such as Cognitive Behavioral Therapy for Insomnia, bright light therapy, circadian rhythm optimization, and Lifestyle Medicine. Michelle is passionate about advocating for improved patient access to Cognitive Behavioral Therapy for Insomnia and other evidence-based treatments in sleep medicine and has served on several professional committees through the American Academy of Sleep Medicine and the Society for Behavioral Sleep Medicine on these topics. When she is not practicing medicine, Michelle enjoys spending time with family, hiking, biking, yoga, cooking and spending as much time outdoors as possible.
