In a severely sleep-deprived society, “How much sleep do I need?” isn’t a pertinent question but an imperative one.
Understanding your sleep need is the first step to staving off the crippling effects of sleep deprivation that undermine physical wellbeing, cognitive performance, and mental health.
Your sleep need is genetically determined and fixed from young adulthood. Unfortunately, the recommended amount of sleep that sleep boards well-meaningly but misleadingly issue typically falls short of your actual need. This is a reason why many of us underestimate how much sleep we need and thus suffer from a lack of sleep.
Ahead, we debunk the various myths clouding the sleep discourse to unveil how much sleep you actually need.
Disclaimer: This post is not intended as medical advice. While the RISE app supports natural sleep patterns and boosts sleep hygiene, it does not treat medical conditions like sleep disorders.
PSA: Not everyone needs eight hours of sleep. Or any other generalized recommendations like “7-9 hours” or “more than six is fine.”
Instead, your sleep need is genetically determined and fixed when you become a young adult.
For the record, the average sleep need is around 8 hours and 10 minutes per night (plus or minus 44 minutes or so). A not-insignificant percentage of the population (13.5%) may need nine hours or more.
Contrasting sleep patterns as a baby and an adult, you’ll see a stark difference.
Newborns and infants need about 14-16 hours of sleep, with a 50/50 split between rapid eye movement (REM) sleep and NREM (non-REM) sleep. At five years of age, the total sleep duration dwindles to 11 hours, with a 70/30 split between NREM and REM sleep. Once you’ve reached your late teens, this NREM:REM ratio eventually stabilizes at 80:20.
The best way to sum up the topic of sleep need is this 2018 review in the Journal of Nature and Science of Sleep: “Although sleep recommendations are a good tool for public health surveillance, they need to be adapted on a case-by-case basis (not a one-size-fits-all recommendation).”
When your body is biologically inclined to sleep changes over your lifetime.
Newborns (0-3 months) snooze on and off throughout the day and night because their circadian rhythms have yet to fully emerge. Once their internal body clocks are established, their sleep patterns become more nocturnal, much to the relief of new parents.
Daytime naps and middle-of-the-night awakenings are common among preschoolers (aged 3-5 years old). When kids hit the school-age group (6-13 years old), their total sleep time gradually shortens as they go to bed later and wake up earlier.
Short-sleeping then ratchets up several notches during teenhood as puberty hits. The two-hour sleep phase delay in the teen’s body clock means they now go to sleep at around 11 p.m. (or later) compared to earlier bedtimes of 9 to 10 p.m.
Possible reasons behind this phenomenon include increased resistance to sleep pressure, a surge in sex hormones, and heightened sensitivity to light. Coupled with late-night blue-light exposure from smartphones and TV screens, it’s safe to say that the average teen ends up sleeping much later than their parents want them to (and much less in total than they need).
Later in life, older adults revert to an early sleep schedule as they undergo a circadian shift to an early-bird chronotype. Despite what we assume, we do not need less sleep as we age. It’s more the case of sleep becoming increasingly challenging to come by.
You can blame it on age-related factors like a decline in slow-wave sleep (aka deep sleep) and melatonin production (the sleep-promoting hormone). Of course, sleep disorders like sleep apnea and physical health issues such as obesity, high blood pressure, and heart disease are linked to aging, too. Not to mention, as you grow older, you’re likely to experience lifestyle changes that dampen the biological sleep pressure – think reduced physical activity – and other conditions, like less social interaction, needed for a good night’s sleep.
Under certain circumstances, your body needs more sleep than your biological need.
The most obvious one would be sleep deprivation, in which your body is programmed to catch up on its sleep debt, as evident from the more intense wake-up grogginess and daytime drowsiness to lull you back to sleep. Another prime example would be when you’re sick.
Illness prompts your body to release sleep-inducing proteins that hike up your body’s temperature as a defense mechanism against the virus. The fever plus the pathogen intensifies sleepiness because in its weakened state, your body needs healthy, naturalistic sleep more than ever.
As we’ll explain, chances are you’re not getting the amount of sleep your body needs and suffer from sleep debt. This is the amount of sleep you’ve missed out in the past 14 days relative to your sleep need. It’s the reason why you’re objectively underperforming in all the ways that matter — physically, emotionally, and cognitively, even though subjectively you might feel fine (something we’ll also explain).
Here are three pitfalls you may have overlooked:
By all accounts, you probably underestimate your sleep need. Don’t feel bad, though. You likely have been led astray by sleep board recommendations that reflect the amount of sleep the population is getting, not what it necessarily needs.
In other words, these so-called “ground rules” aren’t actually tailored to your unique sleep need. Case in point: The National Sleep Foundation’s guideline of 7-9 hours for healthy adults may be notionally helpful. In reality, though, the bare minimum for this guideline (seven hours) is too little to keep your sleep health in tip-top condition.
Sleep need distribution follows a bell curve, with the average at about 8 hours and 10 minutes (give or take 44 minutes or so). To reiterate, around 13.5% of the general public needs nine hours or more of sleep per night. While this average only slightly exceeds the oft-repeated endorsement of eight hours a night, it means a good chunk of the population need (much) more than this to to feel and function at their best.
Needless to say, the probability that you biologically need only five hours of sleep can be rounded to zero. Currently, there are only three genes that let you survive on 4-6 hours of sleep per night and their occurrence is exceedingly rare. Case in point: One of these genes is present in “fewer than one in 4 million people.”
So, should we still trust the sleep boards’ recommendations? Per the earlier 2018 review, while these generalized sleep recommendations tell us “what is normal (or not) in the population and provide a yardstick for practitioners and educators when dealing with sleep-related issues,” they are still primarily dependent on “observational studies using self-reported sleep duration.” Unfortunately, such studies are notoriously inaccurate, and “by no means indicate anything about what the ideal or optimal sleep duration should be.”
To confound the matter, you likely overestimate time spent asleep in bed. Study after study shows that self-reported sleep is always lower than objectively tracked sleep. After all, you take some time to fall asleep and may get up in the middle of the night to use the facilities and such. As such, it’s unrealistic to expect your sleep efficiency to be at 100%.
As a society tottering on the legs of sleep deprivation, we often brush off the ensuing sleepiness in the name of “getting things done.” Unfortunately, the facade of feeling more or less fine means we misinterpret vital cues that signal our need to get enough sleep. As William Dement put it, “Drowsiness is red alert.”
A relatable example would be immediately falling asleep as soon as your head hits the pillow. This is, by no means, an indication that you’re a “good” sleeper, as we take approximately 20 minutes to fall asleep. Instead, it’s a ramification of sleep debt.
More importantly, your brain and body are tricking you as we all subjectively adapt to sleep loss. You can credit it to the constant rushes of cortisol, an alertness hormone that thrives under conditions of sleep deprivation. On top of that, your circadian rhythm is marching on in the background, continuing to give you those energy peaks (which could be so much better with low sleep debt) even when you had little sleep. Objectively, however, you’re suffering downgrades in your health, emotions, and cognition.
“Quality sleep,” for which there is no scientific consensus on its definition, has somehow pervaded and massively confused the sleep discourse. This has misled many people (and sleep trackers) to focus on “sleep quality” rather than sleep quantity. Hail the rise of dubious sleep hacks that “teach” you how to cram your sleep need into a mere five hours (or any number that’s below your actual need).
Unfortunately, that’s not how sleep works.
Without the encumbrances of poor sleep hygiene or medical conditions that interfere with sleep, the brain is biologically programmed to get the healthy, naturalistic sleep it needs in 4-6 sleep cycles every night. Each cycle consists of NREM sleep (split into four stages of sleep) and REM sleep, lasting for roughly 90 minutes. Sleep cycles progress from deep sleep-dominant to REM sleep-dominant over the biological night.
Every stage of sleep, from light to deep sleep, works cohesively to fine-tune your body’s overall well-being during this period of rest. Even if it’s possible, cherry-picking specific stages of sleep will only shortchange your health.
One way to make the case you can’t get all the sleep your brain and body need in a shorter period of time is to look at the natural progression from deep-sleep dominant sleep to REM sleep-dominant sleep over the course of a night. Shortening your sleep duration doesn’t correspond to the same percentage decrease in time spent in each stage of sleep. For example: Imagine your individual sleep need is eight hours but you only slept for six hours last night. You got 25% less sleep than you needed, but that didn’t translate to a quarter decline in REM sleep. Because of the shift from deep sleep dominance to REM sleep dominance, you may have lost 60-90% of the REM sleep you needed!
Further proof of the brain’s self-regulating capabilities includes how it handles “recovery sleep” after sleep restriction by prioritizing REM sleep over deep sleep.
It’s also impossible to know if you’re “hacking” sleep, simply because you can’t tell how much deep or REM sleep you had, unless you’re hooked up to the right equipment in a sleep laboratory, which isn’t commonplace in everyday life. Even if you’re scheduled for a sleep study, these tests are manually done by sleep experts who agree on the final score only about 80% of the time.
For all of these reasons, you can’t “hack” sleep to sleep less than your biological need. Instead, focus on removing impediments (like alcohol and caffeine) to healthy sleep. Meeting your sleep need via good sleep hygiene for sufficient naturalistic sleep is quality sleep.
There are two ways you can calculate your sleep need, one more precise than the other.
As you subjectively adapt to sleep loss, relying on yourself to determine your sleep need is wholly unwise.
Some sleep practitioners suggest keeping a sleep diary where you record how much and how well you slept to analyze your sleep patterns over time. However, this is unreliable because it’s hard to discern your sleep need from the extra sleep going toward paying down sleep debt (chances are you’re probably sleep-deprived anyway). When you rate how good you feel also matters given that sleep inertia (wake-up grogginess) lasts up to 90 minutes from the moment you awake.
Nevertheless, there may be a workaround solution: Measure your nightly sleep need by waking up without an alarm clock for at least a week. After 5+ nights (the first part of the week will likely be spent out-sleeping your sleep need to pay down sleep debt), this method may help you see how long you naturally slept to gauge your sleep need. Still, it may be impractical for those who need to be at work at a certain time or to attend to kids. Even if you’re on vacation, it can still be hard to discern when you went to bed from when you fell asleep.
Using your own judgment involves wooly guesswork that may not bear fruit. Thankfully, there’s a much more reliable option — the RISE app.
RISE uses sleep-science-based models and the past 365 nights of sleep data tracked by your phone to learn your unique sleep biology and calculate your sleep need in hours and minutes. This is why RISE is better than any sleep need “calculator” out there. It uses your data (remember how your need is genetically unique to you?), giving you a much more definite answer.
What’s more, RISE leverages phone motion-based sleep detection to monitor the start and end of your sleep schedule, night-time awakenings (if any), and gauge your nighttime sleep duration. Weighing this number against your sleep need, RISE goes one step further to effectively calculate your sleep debt.
Aside from measuring your sleep need and debt, the RISE app also guides you to sleep better. Here’s how:
As you can see, RISE helps you figure out and consistently and sustainably meet your sleep need. Download the RISE app today for better sleep for better days.
From birth to the age of five, you likely need between 11 and 16 hours of sleep. Adults need on average 8 hours and 10 minutes (give or take 44 minutes or so). We don’t need less sleep when we age; it’s just that sleep when we’re older can be harder to come by.
The average adult’s sleep need is genetically determined and thus unique to the individual. Scientific evidence indicates the average sleep need is around 8 hours and 10 minutes per night (plus or minus 44 minutes or so). A not-insignificant percentage of the population (13.5%) may need nine hours or more.
Given that the average sleep need is around 8 hours and 10 minutes per night (with some needing nine hours or more), it’s definitely not OK — or recommended — to settle for only 5, 6, or 7 hours of sleep.
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