Is 7 Hours of Sleep Enough? What the Research Says About the Minimum That Protects Health

The alarm sounds at 6:10 and the arithmetic begins before your feet touch the floor. Lights out just after eleven, so roughly seven hours. Is that passing or failing? That small daily calculation has turned into one of the most searched health questions of the year, and the phrasing people type is almost always the same: is 7 hours of sleep enough?

Two things pushed it into the spotlight. Social feeds are full of “sleepmaxxing” routines promising nine or ten hours of perfectly optimized rest, while a counter-wave of creators insists that six hours is plenty if you “sleep efficiently”. Meanwhile the American Heart Association now scores sleep duration alongside blood pressure and cholesterol as a core measure of cardiovascular health, which has made the number on your tracker feel like a lab result.

As of this writing in 2025, the research gives a clearer answer than the arguments suggest. It is not a mystical threshold, but it is a well-supported one, and the reasons behind it are worth understanding.

What changed recently to make seven hours a headline number

The seven-hour figure is not new. In 2015 the American Academy of Sleep Medicine and the Sleep Research Society published a joint consensus statement, after a year-long review by a 15-member expert panel, that adults aged 18 to 60 should sleep seven or more hours a night on a regular basis. The CDC adopted that threshold, and its refreshed sleep pages, updated in 2024, still list “7 or more hours” as the adult recommendation.

What has shifted is how seriously the number is treated by the heart community. In June 2022 the American Heart Association expanded its heart-health checklist from “Life’s Simple 7” to “Life’s Essential 8”, and the new eighth item was sleep. Adults scoring the top mark on that metric sleep seven to nine hours a night; less than four hours or ten or more scores lowest. For the first time, a cardiovascular organization put sleep duration on the same scorecard as smoking, diet, physical activity, weight, blood pressure, blood sugar and cholesterol.

Research has reinforced the figure rather than overturning it. A 2022 analysis of roughly 500,000 middle-aged and older adults in the UK Biobank, a long-running British health database, found that cognitive test performance and mental health peaked at around seven hours of sleep and declined on either side. Separate UK Biobank work published in 2023 reported that how regular a person’s sleep timing was predicted mortality about as strongly as how long they slept.

The online noise, then, sits on top of a stable scientific consensus. The guideline did not move; public attention did, and the question people are asking is the right one. The next sections explain what the evidence does and does not show about where the floor sits.

Is 7 hours of sleep enough for most adults? What the guidelines actually say

Read the consensus statement carefully and two words carry the weight: “or more”. The panel did not conclude that seven hours is ideal. It concluded that sleeping less than seven hours on a regular basis is associated with adverse health outcomes, and that above seven hours the evidence becomes less certain about how much extra is helpful. Seven is where the risk curve flattens, not where the benefit stops.

The panel also drew a sharp distinction between “regular” and “occasional”. One short night after a late flight or a sick child is a normal part of life; the concern is a pattern that repeats most nights for months and years. In US surveys, about one in three adults report routinely sleeping fewer than seven hours, so a large share of the population is living below the recommended floor.

Guidelines from the NHS, Mayo Clinic and MedlinePlus echo the same range, usually phrased as seven to nine hours for adults. The slight differences in wording reflect how the evidence was weighed rather than disagreement about the science. The British guidance leans toward the upper end as a target; the American consensus emphasizes the lower bound because it was built to answer a public health question: how little is too little?

So, is 7 hours of sleep enough? For a healthy adult who falls asleep without a struggle, wakes without an alarm most days and does not feel drowsy in meetings or at the wheel, seven hours of real sleep meets the recommendation. For someone who needs three alarms, dozes on the train and sleeps ten hours on a Saturday, seven hours is a sign of a deficit, not a success. The number is the same; the meaning depends on the body reporting it.

How much sleep do adults need by age? The ranges in one table

Sleep need changes across the lifespan, mostly in one direction: newborns need the most, and the requirement falls through childhood and adolescence before settling in adulthood. The table below summarizes the CDC’s age-based recommendations, which draw on the American Academy of Sleep Medicine and National Sleep Foundation reviews.

Age group	Recommended sleep per 24 hours	Where seven hours sits
School age (6–12 years)	9–12 hours	Well below the minimum
Teens (13–17 years)	8–10 hours	Below the minimum
Adults (18–60 years)	7 or more hours	At the floor
Adults (61–64 years)	7–9 hours	At the floor
Adults (65 years and older)	7–8 hours	At the floor

Two patterns in that table deserve emphasis. First, seven hours is never “plenty” for anyone under 18. A teenager who reports seven hours on school nights is short by at least an hour, and adolescent biology compounds the problem because puberty shifts the internal clock later, making early bedtimes genuinely hard rather than simply undisciplined.

Second, the oft-repeated idea that older adults need much less sleep is not supported. The recommended range narrows slightly after 65, but the lower bound stays at seven. What changes with age is sleep architecture: deep sleep becomes lighter and shorter, awakenings grow more frequent, and the body’s clock drifts earlier. Older adults often spend more time in bed to achieve the same amount of sleep, which can look like “needing less” when it is really sleeping less efficiently.

A final note on the question how much sleep do adults need: these are population ranges, not prescriptions. A small minority genuinely thrives on slightly less and a larger minority needs more, which is why the guidance pairs the number with how you feel and function.

What the evidence actually says, and how strong it is

Not all sleep research carries equal weight, so it helps to sort the evidence into tiers. An observational study follows people and records what happens to them; it can show association but not prove cause. A randomized controlled trial assigns people to different conditions by chance, which is the strongest design for cause and effect. Expert consensus sits beneath both and is used where trials are impractical.

Strong observational evidence (very large, consistent, but not causal). Dozens of cohort studies involving millions of participants, pooled in meta-analyses, show a U-shaped curve: adults who habitually sleep fewer than seven hours have higher rates of obesity, type 2 diabetes, high blood pressure, coronary heart disease, stroke, depression and all-cause mortality than those sleeping seven to eight. The association for short sleep persists after adjusting for age, smoking, income and existing illness. Because sleep cannot be randomly assigned for decades, this is as strong as long-term evidence will get.

Randomized trials (causal, but short-term and in small groups). Laboratory sleep-restriction studies randomly limit healthy volunteers to four, five or six hours for one to two weeks and measure the fallout. These consistently show reduced insulin sensitivity (the body’s responsiveness to the hormone that moves sugar out of the blood), higher blood pressure, increased appetite and calorie intake, and cumulative lapses in attention. They prove that short sleep changes physiology; they cannot tell us what twenty years of it does.

Weaker or uncertain areas. Whether long sleep (nine hours or more) is itself harmful is unresolved; most researchers suspect that undiagnosed illness causes long sleep rather than the reverse. The precise optimum between seven and nine hours also varies by study and probably by person.

Putting the tiers together: the claim that regularly sleeping under seven hours is linked with worse health is about as well supported as any lifestyle finding in medicine. The claim that eight is better than seven for everyone is plausible but far less certain.

Is 6 hours of sleep enough? What the sleep-restriction trials show

The most-cited answer comes from a 2003 experiment at the University of Pennsylvania. Researchers randomly assigned 48 healthy adults to four, six or eight hours in bed for 14 consecutive nights, with a separate group kept awake for up to three days straight. Volunteers took attention and working-memory tests throughout.

The six-hour group drifted steadily downhill. By the end of two weeks, their performance on a vigilance task had deteriorated to about the level of someone who had been awake for a full 24 hours, and the decline had not leveled off. The four-hour group reached the equivalent of two nights without sleep. Most striking, the restricted sleepers rated themselves only “slightly” sleepy by the end, even as their test scores kept falling. The gap between felt sleepiness and measured impairment widened night by night.

Later trials have filled in the metabolic picture. Restricting healthy young adults to around five hours for a week reduced insulin sensitivity by a magnitude comparable to the difference between a lean and an overweight person. Short sleep lowers leptin, the hormone that signals fullness, and raises ghrelin, the hormone that signals hunger, which helps explain why restricted participants in controlled feeding studies eat several hundred extra calories a day, mostly as late-evening snacks.

So, is 6 hours of sleep enough? For the rare person with a true short-sleep gene variant, possibly. For most adults, six hours sits in the zone where trials show measurable harm to attention, blood sugar handling and appetite regulation within days, and where observational studies show elevated long-term risk. The reassuring part is that the same trials show recovery when sleep is restored. The cautionary part is that the people most affected were the least able to tell.

7 hours of sleep vs 8: does the extra hour matter?

If seven is the floor, is eight the ceiling worth reaching? The honest answer is that the evidence between seven and eight hours is thinner and more mixed than the evidence below seven, and anyone who claims certainty either way is going beyond the data.

Large cohorts tend to show the lowest mortality and cardiovascular risk somewhere between seven and eight hours, with no consistent winner inside that band. The 2022 UK Biobank cognition study put the peak at seven hours for adults aged 38 to 73, but its participants were middle-aged and older, and the effect sizes between seven and eight were small. In younger adults, laboratory studies suggest that eight hours in bed is roughly what it takes to produce seven to seven and a half hours of actual sleep, which matters for the next section.

Where the extra hour clearly helps is in specific situations rather than for the whole population. People learning a new motor skill or studying intensively consolidate more of that memory during the extra REM-rich sleep that happens late in the night; REM is the rapid eye movement stage in which most vivid dreaming occurs. Athletes in training show faster reaction times and fewer errors when sleep is extended toward nine or ten hours in small trials. People fighting an infection or recovering from surgery often need more. Anyone carrying a sleep debt from a short week benefits from the extra time, at least partly.

In the 7 hours of sleep vs 8 debate, the most defensible position is this: seven is a minimum to protect against the well-documented harms of short sleep; eight is a sensible target for people who feel better on it or whose lives demand peak learning and physical performance. Treat the eighth hour as an opportunity rather than an obligation, and pay more attention to never dipping below the seventh.

Is 7 hours of sleep enough if you feel fine on it? The problem of self-assessment

This is where the viral advice most often goes wrong. Many people who sleep six and a half or seven hours report feeling perfectly well, and they are not lying. The difficulty is that chronic sleep restriction blunts the ability to perceive its own effects, something the Pennsylvania trial demonstrated with unusual clarity: people adapted to feeling tired long before their brains adapted to being tired.

Genetics do create true exceptions. A handful of rare variants, the best known in a gene called DEC2 that helps regulate the body clock, allow carriers to sleep around six hours with no measurable deficit in attention or memory. Researchers estimate these variants affect well under one percent of people. The practical test is simple: a true short sleeper wakes refreshed without an alarm, never “catches up” on days off and does not rely on caffeine to function. Most people who believe they are short sleepers fail at least one of those three.

A more reliable self-check uses behavior rather than mood. Over two typical weeks, ask yourself:

• Do I need an alarm to wake on weekdays, and do I hit snooze?
• Do I sleep 90 minutes or more longer on free days than on work days?
• Do I doze off when reading, watching television or riding as a passenger?
• Do I need caffeine within an hour of waking to feel alert?
• Have colleagues or family commented that I seem irritable or forgetful?

Two or more “yes” answers suggest that seven hours, or whatever you are actually getting, is not enough for you. None of these signs is a diagnosis, but together they are a more honest readout than how you feel at 9 a.m. after a strong coffee. Feeling fine is a reasonable starting point; it is not sufficient evidence.

Seven hours asleep is not seven hours in bed

A detail that quietly undermines many people’s arithmetic: the recommendation refers to time asleep, not time between lights-out and alarm. Nobody sleeps continuously. Healthy adults typically take 10 to 20 minutes to fall asleep and spend another 20 to 30 minutes awake across the night in brief arousals, most too short to remember. Sleep medicine calls the proportion of time in bed actually spent asleep “sleep efficiency”, and a figure of 85 percent or higher is considered normal.

Run the numbers. Seven hours in bed at 85 percent efficiency yields just under six hours of sleep. To bank a genuine seven hours, most adults need to allow about eight hours between getting into bed and getting up. This single correction explains why so many people who “go to bed at eleven and get up at six” and feel wretched are not imagining it: they are logging six hours of sleep while believing they log seven.

Wrist trackers and smart rings complicate things further. Consumer devices estimate sleep from movement and heart rate, and in validation studies they do a fair job of detecting whether you are asleep or awake but a poor job of distinguishing light, deep and REM stages; some overestimate total sleep by counting quiet wakefulness as sleep, others underestimate it. A tracker is useful for spotting trends, such as a consistently later bedtime, and much less useful as a nightly verdict. If a device tells you that you had 7 hours and 3 minutes, treat the first digit as meaningful and the rest as decoration.

The practical takeaway is to protect a sleep window of roughly eight hours rather than aiming for an exact seven, and to judge the result by how you function the next day rather than by the device on your wrist.

Why the body seems to need at least seven hours

Sleep is not a single state. Through the night the brain cycles roughly every 90 minutes through light sleep, deep slow-wave sleep and REM sleep, and a full night contains four to six such cycles. The distribution is uneven: deep sleep dominates the first half of the night, REM the second. Cut the night from eight hours to six and you do not lose a quarter of each stage; you lose a disproportionate share of REM and of the late-night processing that depends on it.

Several repair jobs appear to be scheduled across those cycles. Deep sleep is when the pituitary gland releases most of its growth hormone, which supports tissue repair and muscle recovery. Memories formed during the day are replayed and stabilized across both deep and REM stages, which is why a short night after studying reliably reduces recall the next day in controlled experiments.

Animal research has added a striking mechanism. In mice, the spaces between brain cells expand by about 60 percent during sleep, allowing cerebrospinal fluid to flush out metabolic waste, including beta-amyloid, the protein that accumulates in Alzheimer’s disease. Scientists call this the glymphatic system. Human imaging studies show hints of the same clearance, and one small trial found that a single night of total sleep deprivation raised brain amyloid levels measurably. This evidence is early and mostly animal-based, so it supports the plausibility of a sleep minimum rather than proving one.

Metabolically, the picture is firmer. The sleep-restriction trials described earlier show that cutting sleep raises evening cortisol, the stress hormone, reduces insulin sensitivity and increases sympathetic nervous activity, the “fight or flight” branch that raises heart rate and blood pressure. Blood pressure normally dips 10 to 20 percent overnight; shorten the night and the dip shrinks. None of these processes fits comfortably into six hours, which is the biological reason the epidemiology looks the way it does.

Can you catch up on sleep at the weekend?

The weekend lie-in is the most popular sleep strategy in the world, and the research verdict is “partly”. Sleeping longer on free days does reduce subjective sleepiness and restores some attention performance, so it is far better than not catching up at all. The question is whether it repairs the deeper physiological damage.

A 2019 randomized trial at the University of Colorado offers the clearest test. Healthy adults were assigned to nine hours of sleep, five hours of sleep for nine days, or five hours on weekdays with unrestricted weekend recovery sleep followed by another round of restriction. Both short-sleep groups gained weight and snacked more after dinner. The weekend recovery group’s insulin sensitivity did not bounce back; by the second week of restriction it had fallen as much as, or more than, in the group that never caught up. Their body clocks were also pushed later by the weekend schedule, making Monday harder.

Observational data from large Swedish and American cohorts are a little kinder, suggesting that people who sleep short on weekdays but long on weekends have mortality similar to consistent seven-hour sleepers, whereas people who sleep short every day do not. The two findings are not contradictory: catching up may offset some long-term risk while failing to prevent short-term metabolic disruption, and the effect may depend on how large the weekday deficit is.

A reasonable rule emerges. An extra hour or so on a day off after a demanding week is a healthy recovery habit. A pattern of five hours Monday to Friday and ten hours on Saturday is a treadmill, and the trial evidence says the body does not fully reset. Shifting bedtime by three or more hours between work days and free days, sometimes called social jet lag, carries its own associations with weight gain and poorer mood. Consistency is the cheaper and better-supported fix.

Does sleep quality matter more than duration?

Duration is the easy number to count, which is why guidelines lead with it, but the research increasingly treats quality and regularity as co-equal. Seven hours fragmented by a hundred brief awakenings is not the same as seven hours of consolidated sleep, and the person experiencing the former often has no idea.

The most common hidden cause of poor quality is obstructive sleep apnea, a condition in which the upper airway repeatedly narrows or closes during sleep, dropping oxygen levels and jolting the brain partly awake dozens of times an hour. Sufferers may spend eight hours in bed, wake unrefreshed and be told by a partner that they snore loudly or seem to stop breathing. Untreated moderate to severe apnea is associated with high blood pressure, atrial fibrillation and stroke in observational studies, and treatment trials show improvements in daytime sleepiness and blood pressure. Here, adding hours solves nothing; the problem is inside the hours.

Regularity has emerged as the other major variable. In the 2023 UK Biobank analysis of around 60,000 people who wore wrist monitors for a week, those whose sleep and wake times varied most from night to night had notably higher mortality over the following years than the most regular sleepers, and the effect was at least as large as the effect of total sleep time. A separate 2023 study of 2,000 older adults found that irregular sleepers had a higher incidence of hypertension. These are observational findings, so they show association, but they fit what is known about the body clock: hormones, blood pressure and glucose metabolism all run on a schedule that irregular sleep scrambles.

The best reading of the evidence is not “quality over quantity” but “quantity, then quality, then consistency”, with all three mattering. Seven hours is the entry ticket. What happens inside those hours, and whether they occur at the same time each night, determines how much they protect.

Common myths about the seven-hour rule

Viral sleep content thrives on confident claims that sound like physiology. Several deserve a direct correction.

“You can train your body to need less sleep.” Trials show the opposite. People restricted to six hours did adapt to feeling less sleepy, but their measured performance kept worsening. The brain learns to tolerate deprivation; it does not learn to need less.

“Six hours is fine if your sleep is efficient.” Sleep efficiency describes how much of your time in bed you spend asleep, not how much restoration each hour delivers. A highly efficient six hours is still six hours, and that is the amount shown in randomized trials to impair attention and insulin sensitivity within a week.

“Older adults only need five or six hours.” Recommendations for adults over 65 are seven to eight hours. Older people sleep more lightly and wake more often, so they often achieve less; needing less and getting less are not the same thing.

“Sleeping more than eight hours is dangerous.” Long sleep is associated with worse outcomes in cohort studies, but the most likely explanation is reverse causation: depression, heart failure, apnea and other illnesses make people sleep longer. No trial has shown that extending sleep in a healthy person causes harm.

“Your tracker knows whether you got enough deep sleep.” Consumer devices identify sleep stages with modest accuracy; validation studies routinely find them misclassifying a third or more of sleep epochs. They are fine for trends and poor for verdicts.

“Seven hours is the perfect amount for everyone.” The 2022 cognition study is often quoted this way. It found a peak around seven hours in middle-aged and older adults, not a universal optimum, and the guideline it is used to support actually says “seven or more”.

Practical ways to protect seven hours without turning sleep into a project

The most effective sleep advice is unglamorous and well supported by behavioral trials. It starts with the calendar rather than the bedroom.

Anchor the wake time. Rising at the same time every day, within an hour even on weekends, is the single intervention most consistently shown to stabilize the body clock and improve sleep quality. Bedtime can flex a little; wake time should not. Work backward from it to set a lights-out that allows roughly eight hours in bed.

Shape the day for the night. Daylight within an hour of waking strengthens the clock signal that makes sleepiness arrive on schedule 16 hours later. Regular exercise improves deep sleep in trials, though vigorous sessions in the last hour or two before bed can delay sleep onset for some people. Caffeine has a half-life of around five to six hours, meaning half of a mid-afternoon coffee is still circulating at bedtime; most sleep specialists suggest a cutoff around early afternoon. Alcohol speeds falling asleep but fragments the second half of the night and suppresses REM, so it is a poor sleep aid despite its reputation.

Keep the bedroom boring. Cool, dark and quiet is the evidence-based trio; bright screens close to bedtime push the clock later and the content keeps the mind alert. If you cannot sleep after about 20 minutes, getting up and doing something dull in dim light until drowsy is a core technique of cognitive behavioral therapy for insomnia, or CBT-I, the structured program recommended as first-line treatment for chronic insomnia by sleep medicine bodies.

On supplements and medicines: melatonin is widely sold and widely discussed, and its evidence base is strongest for jet lag and certain circadian rhythm disorders rather than for ordinary short sleep in adults. Whether it, or any sleep medicine, is appropriate is a decision for your own clinician, who can weigh interactions and underlying causes. Nothing here should replace that conversation.

When to see a doctor about your sleep

Most people who sleep too little have a schedule problem, and the fixes above are the right first step. Some have a medical problem that no amount of discipline will solve, and a few have symptoms that should not wait. Speak to a doctor if you notice any of the following.

• Loud snoring with pauses, gasping or choking during sleep, reported by a partner or noticed on waking, especially with morning headaches or daytime sleepiness. These are hallmark signs of obstructive sleep apnea, which is treatable and important to identify.
• Falling asleep unintentionally while driving, in conversation or at work. Sleepiness severe enough to intrude on daytime life is never normal and can be dangerous.
• Difficulty falling or staying asleep at least three nights a week for three months or more, with daytime consequences. This meets the definition of chronic insomnia, for which CBT-I and medical evaluation are available.
• An irresistible urge to move the legs at rest or at night, relieved by movement, which may indicate restless legs syndrome and sometimes iron deficiency.
• Persistent low mood, anxiety or loss of interest alongside sleep changes. Sleep disruption and mood disorders are tightly linked, and treating one often helps the other.
• Needing nine or ten hours and still waking exhausted for weeks, or a sudden change in sleep need, which can signal thyroid problems, anemia, depression or other conditions worth checking.
• Chest pain, palpitations or breathlessness that wake you from sleep. Seek urgent care for these.

Bring specifics to the appointment: a two-week sleep diary noting bedtime, wake time, awakenings, caffeine and alcohol is more useful to a clinician than any tracker summary. If you take prescribed medicines that affect sleep or alertness, do not stop or adjust them on your own; raise the question with the prescriber. A primary care doctor can address most sleep complaints and will refer to a sleep specialist when a sleep study or specialist treatment is warranted. The point of asking “is seven hours enough” is to protect your health, and sometimes the honest answer is that the hours are not the problem.

Frequently asked questions

What happens if you sleep less than 7 hours regularly?

Regularly sleeping under seven hours is associated in large cohort studies with higher rates of obesity, type 2 diabetes, high blood pressure, heart disease, stroke, depression and earlier death. Short-term randomized trials show the mechanisms: within a week, restricted sleep reduces insulin sensitivity, raises blood pressure and appetite, and causes cumulative lapses in attention. The effects build quietly, and most people underestimate how impaired they have become.

Is 7 hours of sleep enough for a 50-year-old?

Yes, for most people in their fifties seven hours of actual sleep meets the guideline of seven or more hours for adults aged 18 to 60. The UK Biobank study that found cognitive performance peaked at around seven hours included exactly this age range. The caveat is quality: sleep apnea becomes more common in midlife, so unrefreshing sleep or loud snoring deserves a medical check even when the hours look adequate.

Is 6.5 hours of sleep enough?

Six and a half hours falls just below the recommended minimum, and sleep-restriction trials show measurable effects on attention and glucose handling at around six hours. Whether half an hour matters depends on how you function: waking without an alarm, no daytime drowsiness and no weekend lie-ins suggest you may be fine. If you need an alarm and caffeine to get going, extending your sleep window by 30 to 60 minutes is a low-risk experiment.

Is 7 hours of sleep enough for exercise recovery and building muscle?

Seven hours is the minimum, and many athletes benefit from more. Most growth hormone release occurs during deep sleep, and small trials extending sleep toward nine or ten hours in college athletes improved sprint times and reaction speed. Sleep restriction, by contrast, reduces muscle protein synthesis and impairs glucose uptake in observational and laboratory studies. During heavy training blocks, aiming for eight hours or more is reasonable.

Does 7 hours of sleep include the time it takes to fall asleep?

No. The recommendation refers to time actually asleep. Falling asleep typically takes 10 to 20 minutes, and healthy adults spend another 20 to 30 minutes awake in brief arousals across the night. Taken together, seven hours in bed usually produces about six hours of sleep, so most people need roughly eight hours between lights-out and getting up to bank the recommended seven.

Can I train myself to need less sleep?

Not according to the evidence. In controlled trials, people restricted to six hours for two weeks did adapt to feeling less sleepy, but their measured performance kept deteriorating night after night. The sense of adaptation is real; the physiological need does not change. True short sleepers who thrive on six hours carry rare gene variants affecting well under one percent of people, and they do not need alarms or caffeine to function.

Is it better to get 7 hours straight or 8 hours broken into two blocks?

Consolidated sleep is generally better. Sleep cycles run about 90 minutes, and deep sleep and REM are distributed unevenly across the night, so fragmenting sleep disrupts that pattern. That said, a planned short daytime nap of 20 to 30 minutes added to a seven-hour night is well tolerated and improves alertness in trials. Frequent unplanned waking that splits the night, however, is a reason to investigate causes such as sleep apnea.

Is sleeping 9 or more hours a night bad for you?

Long sleep is associated with higher mortality and cardiovascular disease in cohort studies, but the evidence that it causes harm is weak. The most accepted explanation is reverse causation: depression, heart failure, untreated sleep apnea and other conditions make people sleep longer. No trial shows that extending sleep harms a healthy person. A sudden new need for nine or ten hours, though, is worth discussing with a doctor.

Is 7 hours of sleep enough for a teenager?

No. Recommendations for ages 13 to 17 are eight to ten hours per night, so seven hours leaves a teenager at least an hour short. Adolescent biology shifts the internal clock later during puberty, making early bedtimes genuinely difficult, which is why early school start times are a recognized public health concern. Chronic short sleep in teens is linked with poorer grades, mood problems and higher injury risk.

Should I take melatonin to get to 7 hours?

Melatonin is a hormone that signals night to the body clock, and as a supplement its evidence is strongest for jet lag and circadian rhythm disorders rather than for ordinary short sleep in otherwise healthy adults. Trials in general insomnia show small effects on how fast people fall asleep. Whether it is appropriate for you, and how it fits with other medicines or conditions, is a decision for your own clinician.

References

• CDC: About Sleep, including how much sleep you need by age
• NIH National Heart, Lung, and Blood Institute: Sleep Deprivation and Deficiency
• MedlinePlus: Healthy Sleep

This article is for general information only and is not a substitute for professional medical advice. Please consult a qualified doctor about your individual situation.