People Who Need 7 Hours, People Who Need 10 Hours - The Reason There Isn't Just One "Ideal Sleep Duration"

"The ideal is for humans to sleep 8 hours a day."

Anyone who has researched sleep has probably heard this at least once.

Going to bed at 11 PM and waking up at 7 AM. If you can sleep exactly 8 hours, it's healthy; if you sleep only 6 hours, you're sleep-deprived. Conversely, if you sleep 9 or 10 hours, you might worry, "Am I sleeping too much?"

However, when you look at research and recommendations from sleep experts, the issue is not that simple.

For healthy adults, the general guideline is 7 to 9 hours of sleep. However, what is optimal within this range varies from person to person.

Some people naturally wake up after about 7 hours and can focus and be active all day. On the other hand, some clearly feel off unless they sleep for about 8.5 or 9 hours.

Even on social media, experiences vary widely, from people who say "6 hours is fine" to those who claim "I can't function without 9 to 10 hours."

So, how many hours should we actually sleep?

"8 hours" is not an absolute answer

First, it's important to know that the number "8 hours" doesn't have an absolute medical significance.

The National Sleep Foundation recommends 7 to 9 hours for adults aged 18 to 64, and about 7 to 8 hours for those aged 65 and older.

The CDC also recommends 7 or more hours of sleep for adults aged 18 to 60.

In other words, it's not about "7 hours and 59 minutes is insufficient" or "8 hours and 1 minute is ideal."

The number 8 is easy to remember because it sits near the middle of the general recommended range for adults, which is why it became widely known.

There are individual differences in the amount of sleep needed in the first place.

It varies not only by age but also by daytime activity level, lifestyle rhythm, physical condition, and previous sleep patterns.

It's not uncommon to sleep longer than usual when you're unwell or have been sleep-deprived for days.

There's no need to worry about "oversleeping" just because you slept for 9 hours one night.

What's important is to look at the long-term state rather than just the daily numbers.

Sleeping 7 hours doesn't guarantee peace of mind

The number "7 hours or more" is often used for adult sleep.

However, this doesn't mean that "7 hours of sleep is sufficient for everyone."

Some people naturally wake up before their alarm after 7 hours and feel sharp in the morning.

Others feel groggy in the morning and experience strong drowsiness after lunch, even after 7 hours of sleep.

It's difficult to simply judge that both are getting enough sleep just because they both sleep for 7 hours.

Therefore, to know if your sleep is sufficient, it's important to consider your daytime condition, not just sleep duration.

Do you feel refreshed when you wake up in the morning?

Do you frequently feel sleepy during work or study?

Do you sleep significantly longer on weekends than on weekdays?

Do you rely on large amounts of caffeine to get through the day?

These signs can also be clues to consider when thinking about sleep.

On social media, "7 hours is enough" and "10 hours are necessary" coexist

In fact, looking at experiences shared on social media makes it clear that the necessary sleep time varies greatly from person to person.

 

In July 2026, a topic was posted in the sleep community on the overseas forum Reddit, asking "How many hours of sleep do you need to function at your best?"

There, aside from the generally known 7 to 9 hours, people shared their personal experiences.

While some people find 7 to 9 hours just right, others say they need at least 10 hours.

In another post from 2026, someone who needs about 9 hours to feel fully recovered expressed frustration, saying, "Many around me say they're fine with about 6 hours, making me feel like I'm spending too much time sleeping."

Interestingly, sleeping longer doesn't make everyone feel comfortable.

In a discussion about sleep on Reddit in January 2026, some people said they feel best with about 7.5 hours, while others said 7 to 8 hours is insufficient and they feel just right with about 9 to 10 hours. Meanwhile, some reported headaches if they sleep more than 8 hours.

Indeed, experiences vary from person to person.

On Japanese social media, voices say "6.5 hours is not enough"

Similar reactions can be found in the Japanese-speaking community.

In May 2026, when fatigue and drowsiness became a topic in the Japanese Reddit community, there were reactions like "Is 6.5 hours enough? I can't function without 8 to 9 hours."

There were also voices saying that although they used to sleep only 4 to 5 hours for work, they later realized the importance of sleep and now make sure to sleep at least 7 hours.

In another post, someone shared their experience of using a holiday to sleep without an alarm clock to find out how much sleep they need.

For that person, they eventually settled on about 8 hours, reflecting that they might have been compensating for previous sleep deprivation, although they initially thought they were the type to sleep quite long.

Of course, these social media posts are not medical research.

Since the health status and living conditions of the posters vary, it's not accurate to conclude "9 hours is correct because someone on social media said they needed 9 hours."

However, they are very interesting as evidence of the difficulty in explaining human sleep with a single number like "everyone needs 8 hours."

Why do we cut back on sleep time?

In modern life, sleep is often the first thing to be cut.

You finish work.

You go home.

You have dinner and finish household chores.

Watching videos, playing games, or browsing social media, before you know it, it's midnight.

Since a day only has 24 hours, many people first cut sleep to increase their personal time.

"If I stay up one more hour, I can have one more hour of free time."

At first glance, it seems reasonable.

However, if cutting that one hour reduces your concentration the next day, turning a task that usually takes 2 hours into a 3-hour task, you can't really say you've gained time.

Sleep is not simply "time doing nothing."

Various functions continue in the body and brain even during sleep.

It's important to view sleep not as a waste of time but as necessary time for the next day's activities.

Is "getting used to sleep deprivation" really okay?

Among those who have lived with short sleep for many years,

there are people who say, "I'm used to 5 hours of sleep."

"I've only slept 6 hours since I was young, but I can work normally."

Indeed, there are individual differences in how people perceive sleep.

However, feeling accustomed to short sleep and the absence of effects on the body or cognitive functions are not the same.

Chronic short sleep is associated with drowsiness, decreased concentration and attention, and slower reaction times.

The joint statement by AASM and the Sleep Research Society also recommends that healthy adults regularly sleep 7 hours or more.

Long-term sleep of less than 7 hours is associated with multiple issues such as obesity, diabetes, hypertension, heart disease, stroke, depression, and accident risk.

However, caution is needed here.

Many studies investigate the "association" between sleep duration and disease.

In many cases, it's not proven that sleep deprivation alone causes disease.

There may also be other factors present, such as long working hours, stress, diet, and lack of exercise, along with short sleep.

Still, it's best to avoid unconditionally thinking, "I'm used to it, so it's fine," regarding chronic sleep deprivation.

Is "staying up all night is the same as being drunk" true?

When discussing sleep deprivation, you might see the expression "staying awake for 24 hours is the same as being drunk."

There are studies showing that staying awake for long periods reduces attention and reaction capabilities.

However, since the effects of sleep deprivation and alcohol on the human body are not the same, it's inaccurate to simply equate "being awake for X hours is exactly the same as a blood alcohol concentration of X%."

The important thing here is not comparing numbers.

Even if you think "I'm still okay," strong drowsiness can impair your reaction and judgment abilities.

Especially in driving, drowsiness can lead to significant danger.

If a micro-sleep occurs, where you lose consciousness for just a moment, you can travel a considerable distance on a highway in just a few seconds.

Avoiding continuing activities in a sleepy state is important for safety.

So, is sleeping longer always healthier?

If sleep deprivation is a problem, would sleeping 10 or 11 hours be healthier?

This too is not simple.

Large observational studies have found associations not only with very short sleep but also with long sleep and health issues or mortality rates.

The original article also introduced studies confirming the association of sleep longer than 9 hours with mortality risk, compared to about 7 to 8 hours.

However, it's not appropriate to interpret this as "sleeping more than 9 hours is bad for your health."

There is a possibility of "reverse causation" here.

Some people may need longer rest due to illness or poor health.

Medications may also increase drowsiness.

There may be hidden issues with mental health or sleep itself.

In other words,

it's not that "sleeping longer causes illness,"

but rather that "some problem causes the need for longer sleep."

Cases may include this possibility.

Are people who sleep 9 hours "lazy"?

On social media, it's particularly striking that some people express guilt about needing 9 hours of sleep.

Sleeping 9 hours a day means about 37% of the day is spent sleeping.

With 8 hours for work, plus time for commuting, chores, and meals, the time left for personal use is quite limited.

If there are people around you who say "I'm fine with 6 hours," you might think, "Am I sleeping too much?"

However, securing the necessary sleep time and being lazy are separate issues.

The AASM statement also notes that sleeping more than 9 hours may be appropriate for young adults, those who were previously sleep-deprived, or those recovering from illness.

The important thing is not just the number "9 hours."

Do you wake up refreshed after 9 hours and can function well during the day?

Or do you struggle to wake up even after 10 hours and feel sleepy all day?

These two scenarios have significantly different meanings, even with the same long sleep duration.

The issue of "feeling tired even after 8 hours of sleep"

Another important aspect not to forget is the quality of sleep.

"Even though I'm in bed for 8 hours every day, I feel tired in the morning."

Many people might have experienced this.

In reality, "being in bed for 8 hours" is not the same as "getting 8 hours of quality sleep."

You might take more than 30 minutes to fall asleep.

You might wake up multiple times during the night.

There might be repeated awakenings that you don't remember.

Sleep involves multiple factors, including time, quality, timing, and regularity.

The National Sleep Foundation also emphasizes not only sufficient sleep time but also the quality and regularity of sleep.

Therefore, the goal should not just be to achieve the recommended time, but to consider##HTML_TAG_275