For generations, we have been told that adults need eight hours of sleep every night. It is advice so familiar that many people treat eight hours as a biological requirement.
But sleep research is beginning to paint a more nuanced picture.
A recent article in The Conversation, written by sleep researchers Derk-Jan Dijk and Anne Skeldon, examines new evidence suggesting that there may not be one ideal amount of sleep that applies to every adult. The article draws on a new narrative review published in Brain Medicine and on research examining how people sleep in societies with little exposure to modern artificial light and technology.
The takeaway isn’t that you should stop aiming for eight hours. Nor does the research suggest that six hours is enough for everyone.
Instead, it points toward a more useful question:
How much sleep does your individual body actually need to function and stay healthy?
Where Did the Eight-Hour Sleep Rule Come From?
The idea that eight hours is the ideal amount of sleep has a surprisingly recent history.
The familiar division of the day into eight hours of work, eight hours of recreation and eight hours of sleepemerged during the 19th century. Over time, the eight-hour figure became deeply embedded in our culture as the definition of a healthy night’s sleep.
But a convenient social standard isn’t necessarily the same thing as a biological requirement.
Sleep researchers have long recognized that sleep needs vary among individuals. Age, genetics, health, lifestyle, activity levels and other factors can influence how much sleep a person needs.
The American Academy of Sleep Medicine and Sleep Research Society, for example, recommend that adults regularly obtain at least seven hours of sleep per night for optimal health. Their consensus statement also recognizes substantial individual variation in sleep need.
The National Sleep Foundation generally recommends 7–9 hours for adults, with somewhat different recommendations for older adults.
So why is eight hours treated as such a precise target?
The science isn’t actually that precise.
What Can We Learn From People Living Without Modern Technology?
One of the more interesting pieces of sleep research has looked at traditional societies whose lifestyles are less influenced by electricity, artificial lighting and modern schedules.
Researchers studied three groups living in Tanzania, Namibia and Bolivia: the Hadza, San and Tsimané.
The researchers found that their actual sleep duration was surprisingly short compared with the common assumption that humans naturally sleep for eight or more hours.
Average sleep duration ranged from approximately 5.7 to 7.1 hours per night. The groups generally did not compensate for their shorter nighttime sleep with extensive daytime naps.
That finding is fascinating—but it needs some context.
These communities are not simply “people who have discovered that six hours is enough.” Their environments, physical activity, diet, social structures, exposure to natural light and temperature patterns are very different from those of people living in modern industrial societies.
In fact, the researchers found that sleep timing was closely associated with environmental temperature. Sleep generally began several hours after sunset and ended around dawn, rather than beginning immediately when darkness arrived.
The study therefore raises an important possibility:
Sleep duration is only one part of healthy sleep.
Sleep Quality May Matter as Much as Sleep Quantity
Imagine two people who spend eight hours in bed.
Person A falls asleep quickly, sleeps relatively continuously and wakes feeling refreshed.
Person B spends eight hours in bed but wakes repeatedly, struggles with discomfort, overheats during the night and spends significant portions of the night awake.
Both have “eight hours in bed,” but they have not necessarily received eight hours of equally restorative sleep.
This distinction is important because healthy sleep involves more than duration. The AASM notes that healthy sleep also involves quality, timing, regularity and the absence of sleep disturbances or disorders.
That is one reason the question “How many hours should I sleep?” doesn’t have a single perfect answer.
So How Many Hours of Sleep Do Adults Actually Need?
For most adults, seven to nine hours is still a useful target.
That doesn’t mean everyone needs exactly eight hours.
Some people naturally function well toward the lower end of that range, while others need closer to nine hours. Young adults, people recovering from accumulated sleep loss and people dealing with certain illnesses may sometimes require more sleep.
There are also rare individuals who appear to be natural short sleepers and can function normally on substantially less sleep. These people should not be confused with the much larger number of people who simply adapt to chronic sleep deprivation.
Feeling like you can “get by” on six hours isn’t necessarily evidence that six hours is enough.
Research reviewed by the AASM found that cognitive performance, attention and other measures can deteriorate as sleep duration falls below seven hours, even when people don’t fully appreciate the extent of their impairment.
In other words, your perception of being accustomed to short sleep isn’t necessarily proof that your body is thriving on it.
The Better Question: How Do You Feel During the Day?
Rather than obsessing over whether you got exactly eight hours, pay attention to what happens during your waking hours.
Signs that you may be getting enough sleep include:
- Waking relatively easily without excessive grogginess
- Feeling reasonably alert throughout the day
- Being able to concentrate without constantly fighting sleepiness
- Maintaining a relatively stable mood
- Not needing large amounts of caffeine simply to function
- Sleeping reasonably consistently from night to night
Conversely, persistent daytime sleepiness, difficulty concentrating, irritability or needing excessive amounts of caffeine may indicate that you aren’t getting enough—or that your sleep quality is poor.
If you routinely sleep for what should be an adequate number of hours but still feel exhausted, the issue may not simply be sleep duration. Sleep disorders, fragmented sleep, medications, alcohol, stress and other factors can interfere with restorative sleep.
Your Sleep Needs Can Change With Age
Sleep requirements aren’t fixed throughout life.
Teenagers generally need more sleep than adults, while sleep duration tends to decrease somewhat as people age. The National Sleep Foundation recommends 7–9 hours for adults and 7–8 hours for adults 65 and older.
Your personal sleep requirement can also change temporarily.
You may need additional sleep after:
- Several nights of inadequate sleep
- Illness
- Significant physical activity
- Travel across time zones
- Periods of unusual stress
- Other disruptions to your normal schedule
This is another reason why thinking of eight hours as a rigid biological requirement can be misleading.
What About Sleeping More Than Nine Hours?
The relationship between very long sleep and health is complicated.
Some observational studies have found associations between long sleep duration and various health problems. But that doesn’t necessarily mean that sleeping longer causes those health problems.
People who are ill, recovering from illness or experiencing poor-quality sleep may naturally spend more time sleeping or in bed.
The AASM/SRS consensus panel specifically found insufficient evidence to conclude that regularly sleeping more than nine hours is inherently unhealthy for every adult.
So the answer isn’t “more is always better,” but neither is it “eight hours is mandatory.”
Timing and Regularity Matter Too
The emerging research also reminds us that when we sleep can matter.
Humans have an internal circadian rhythm that responds strongly to environmental cues, particularly light and darkness. Modern life can interfere with those signals through artificial light, electronic devices, irregular schedules and late-night activities.
Research on traditional societies provides an interesting contrast. The three groups studied by researchers generally went to sleep several hours after sunset and woke before sunrise, with sleep timing also influenced by seasonal changes and temperature.
For modern sleepers, this doesn’t mean we need to replicate a hunter-gatherer lifestyle.
It does suggest that paying attention to our body’s natural sleep-wake rhythms may be worthwhile.
Keeping a relatively consistent bedtime and wake time, getting natural light during the day and creating a darker, quieter and cooler sleeping environment can all support healthy sleep habits.
Your Bedroom Environment Matters
Once we stop thinking about sleep as simply a number of hours, the sleeping environment becomes more important.
Temperature is one example.
The human body naturally undergoes changes in temperature as part of the sleep-wake cycle. A bedroom that is too warm, or bedding that traps excessive heat and moisture, can make comfortable sleep more difficult.
This is one reason breathable bedding materials can be an important consideration when creating a healthy sleep environment. Organic cotton sheets can keep you cool.
Natural materials such as wool, cotton and natural latex have different thermal and moisture-management properties than many synthetic materials. Wool, for example, is naturally capable of absorbing and releasing moisture while helping regulate temperature.
A breathable mattress and comfortable bedding won’t determine how many hours of sleep your body needs—but they can help create an environment in which your body can sleep comfortably for the amount of time it needs.
Don’t Turn Sleep Into Another Performance Goal
Perhaps the most useful lesson from the evolving research is that sleep shouldn’t become another number to obsess over.
If you wake up naturally after seven and a half hours feeling rested, there may be little reason to worry that you “failed” to get eight.
If you regularly need nine hours to feel your best, there is no reason to force yourself to sleep less simply because eight hours is considered the standard.
And if you consistently sleep six hours because your schedule doesn’t allow more, feeling accustomed to it doesn’t necessarily mean your body is getting everything it needs.
The goal isn’t to achieve a perfect number.
The goal is sufficient, restorative and consistent sleep.
The Bottom Line: Is Eight Hours of Sleep Still the Goal?
Yes—but perhaps not in the way we’ve traditionally understood it.
Eight hours remains a perfectly reasonable target for many adults. Current expert recommendations continue to support at least seven hours of regular sleep for adults, while the National Sleep Foundation’s general recommendation is 7–9 hours.
What the newer research challenges is the idea that eight hours is a universal biological requirement.
Your ideal amount of sleep may be somewhat shorter or longer.
Instead of asking, “Did I get exactly eight hours?” consider asking:
Did I get enough high-quality sleep to feel alert, healthy and functional today?
That may be a much better way to think about healthy sleep.
A Note on the Research
This article was inspired by the August 2026 The Conversation article “How much sleep do I need? Why you can forget the eight-hour sleep rule,” by sleep researchers Derk-Jan Dijk and Anne Skeldon. The article discusses a new narrative review in Brain Medicine as well as earlier research into natural sleep patterns in pre-industrial societies.
The findings should not be interpreted as a recommendation that adults routinely sleep fewer than seven hours. The strongest established guidance continues to support at least seven hours of sleep for most adults, while recognizing meaningful individual variation.
Sources
- American Academy of Sleep Medicine and Sleep Research Society — adult sleep-duration consensus recommendations.
- National Sleep Foundation — updated sleep-duration recommendations.
- Yetish et al., Natural Sleep and Its Seasonal Variations in Three Pre-industrial Societies, Current Biology.
- Dijk and Skeldon, The Conversation, “How much sleep do I need? Why you can forget the eight-hour sleep rule.”
Healthy Sleep Living is dedicated to exploring the science behind better sleep and the ways your sleep environment—including your mattress, bedding and bedroom—can support healthier, more comfortable rest. Our goal at Plank and Coil is more than just selling products. We want you to get the best sleep possible. Good sleep entails a wholistic approach to your body’s needs.
