The modern world is increasingly busy, hectic and stressful, and many of us are sacrificing more and more of our slumber in an effort to get everything done – indeed, one survey found that up to a third of adults in the US sleep less than seven hours per night.
But is this a wise move? How serious is it if we don’t get enough sleep each night? And how much sleep is considered enough anyway?
To give you all the information you need about these issues and more, in this post, we discuss the question, is six hours of sleep enough?
Six Hours of Sleep: What the Science Says
According to scientific consensus, most adults need between seven and nine hours of sleep per night, although the exact amount varies from person to person.
Furthermore, the amount of sleep a person needs is fixed, so if you’re someone who needs nine hours of sleep per night, you can’t somehow train your body to accept seven hours – you need your nine hours, and there’s nothing you can do about it.
There are some people who genuinely only need six hours per night or even less – which means six hours is all their bodies require to function optimally.
However, this is very different from somebody who really needs eight hours being able to get by on six hours by toughing it out, and this is an important distinction to make.
A person sleeping less than their body’s requirement over a long period will end up functioning far below optimal levels, and their health will begin to suffer in many ways, something we’ll discuss in more detail in a moment.
Adults under 65 who only need six hours a night are rare.
What’s more, although some people believe they can “get used” to sleeping less, this is a misguided notion.
Even if your body comes to accept a state of constant sleep deprivation as normal, and you might become accustomed to living like this, you will nevertheless be experiencing significant symptoms and consequences of a lack of sleep, maybe without even realizing it.
So in short, it’s extremely important to sleep for the amount of time your body requires, and for most adults, six hours just isn’t enough.
What About at Different Ages?
So far, we’ve been talking about adults between the ages of 18 and 64, but our sleep requirements don’t remain constant throughout our lives.
Newborn babies are thought to require around 14 to 17 hours per day, although as with adults, this varies between individuals, and some will need more while some will need less.
However, babies getting less sleep than they require are thought to be at risk of several potentially serious consequences, including decreased brain development, learning problems and more frequent negative emotions.
Weight problems, growth issues and increased frequency of illnesses later in life are also thought to be related to lack of sleep in newborns.
From four months, the amount of sleep required per day drops to around 12 to 16 hours, and by the time a child reaches three to five years, this falls even lower to around ten to 13 hours.
By the time a child reaches their teens – from 13 to 17 – they only need around eight to ten hours, just a little more than adults.
From about 18 to the mid-60s, the amount then stays the same, but then after around 65, sleep requirements tend to drop further, and many older people find they no longer need as much sleep each night.
For every age group, the number of hours each individual requires can vary, and again, some will genuinely need less than the average for their age.
However, if an individual is regularly not sleeping the number of hours their bodies need, it will always have consequences, whatever their age.
Why Do We Need to Sleep?
But why do we need to spend all this time asleep? Wouldn’t it be better if we could just stay awake for longer and fit more work and more play into our lives?
Well maybe, but unfortunately, it doesn’t work like that.
As it happens, science doesn’t have all the answers as to why we need to sleep, but what’s absolutely clear is that we can’t get by without it.
Sleep allows us to form and maintain the pathways in our brains that are essential for learning and remembering, and while we sleep, our brains also perform vital maintenance tasks like removing toxins and getting everything ready to start again the next day.
At the same time, our bodies are also busy taking care of themselves and recharging – this is when our bodies perform jobs like repairing cells and tissue.
All this means that sleep is essential to our well-being, and sleeping fewer hours than our bodies demand is not a wise option – especially in the long term – and for most adults, that means only six hours of sleep per night is not ok.
What Determines How Much We Need to Sleep?
The Circadian Rhythm
Although the exact amount varies from person to person, the number of hours of sleep we need – and when we sleep – is dictated by something called our circadian rhythm, a kind of internal body clock that tells our bodies and minds when to be sleepy and when to be active.
The circadian rhythm takes its cues from nature, and by far the most important of these is light.
When the sun goes down, our brains start releasing melatonin, a chemical compound that makes us feel drowsy. This usually peaks between 2am and 4am, after which, the amount of melatonin released by the brain is reduced.
When the sun comes up, melatonin release reduces even further, and we wake up ready to face the world.
However, part of the reason different people need varying amounts of sleep is because people have different circadian rhythms – so the signals telling us when to sleep and when to be awake differ from person to person.
Sleep Debt – Is It Ok if You Just Sleep Six Hours for One Night?
Coupled with this is something sleep specialists refer to as “sleep debt”.
When we are awake, another compound called adenosine starts to build up in the brain, which also makes us feel sleepy. Then when we sleep, the adenosine dissipates – but if we don’t sleep enough, some of the adenosine will remain.
This means if you miss out on sleeping the required number of hours for several nights, the adenosine will continue to build up as you accrue more sleep debt, and this will leave you feeling increasingly tired and unable to perform at your best.
This is important because it means that if you only sleep for six hours one night, it’s not such a big deal – things only begin to become serious if you sleep less than your body’s required amount over an extended period, leaving yourself living in a constant state of sleep debt.
It also means that if you know you are likely to have a night or two of reduced sleep – perhaps because you have to take a late night or early morning flight – you can anticipate this by sleeping more in the days leading up to the event to build up a kind of “sleep credit”.
Quality Matters, Not Just Quantity
It’s not just how much you sleep, though – the quality of your sleep also matters.
When we sleep, we go through different sleep cycles. These sleep cycles are repeated several times each night, and for you to wake up feeling refreshed, it’s important to spend enough time in each.
As a result, if you wake up often during the night – even without realizing it – you may feel groggy in the morning, and you may suffer from the longer-term effects of sleep deprivation, even if you think you are sleeping eight hours a night.
There are many causes of poor-quality sleep, and they may include things like sleep apnea and restless leg syndrome (RLS).
With sleep apnea, sufferers temporarily stop breathing for a few moments as they sleep, often causing them to wake briefly and then drop back off again.
The sleeper might not remember it the following morning, but if their sleep is constantly interrupted like this, they won’t get enough good-quality sleep and will suffer the same effects as someone who doesn’t sleep enough hours.
RLS is a condition that causes an irresistible urge to move one’s legs – or arms – during sleep. Again, this prevents a person from spending enough time in the various sleep stages, leaving them feeling chronically tired and unable to function properly.
The takeaway from this is that although important, focusing just on a figure like “six hours” is slightly missing the point.
It’s important to get the number of hours of sleep your body demands, but it’s also important for it to be good-quality sleep – otherwise, eight hours of poor sleep can be just as bad as getting six or less hours of good-quality sleep.
What Happens if You Don’t Get the Sleep You Need
So now we know that people need different amounts of good-quality sleep and that the required amount changes throughout one’s lifetime.
We’ve also already mentioned that not getting enough sleep – or not getting enough good quality sleep – can be detrimental to your health, but what problems can it cause in concrete terms?
The list is extensive, but here are some of the most significant.
Reduced Performance Levels
When we lack sleep, we often suffer from daytime drowsiness and a lack of energy, especially when performing boring or monotonous tasks.
We lose our motivation to do anything, and we can have trouble concentrating – for example, you may find yourself drifting off during meetings instead of listening to what is being said.
Sleep deprivation also affects our memories, and it can make it much more difficult to learn things or to solve problems. Creativity is also likely to be significantly reduced, and our productivity – either at school or in the office – will drop.
At the same time, our ability to make sound decisions is reduced, and errors, accidents and risk-taking behavior can all be increased.
Inability to Control Mood
Sleep-deprived people are often irritable and have trouble controlling their emotions – someone who is excessively tired is much more likely to snap at family members, co-workers or schoolmates.
In more extreme cases, sleep deprivation can also lead to depression, which in turn can be a cause of insomnia, creating a vicious cycle.
Sleep deprivation also has known physical consequences. Athletes commonly report reduced performance levels when tired as well as poorer coordination and response times.
If you go to the gym when you’re tired, you will run slower and have less strength for lifting weights, meaning your numbers will fall well short of what you are capable of achieving when fully rested.
Similarly, if you do a physical job, you will have less strength to perform actions such as lifting that you are required to carry out.
Lack of sleep also leaves people with less energy, enthusiasm and motivation to take part in physical activity.
Reduced Quality of Life
As sleep deprivation becomes more chronic, your overall quality of life is likely to suffer.
You are less likely to want to socialize, you may experience a decreased sex drive and you are likely to suffer from a general feeling of malaise.
Long-Term Health Risks
Chronic lack of sleep can also lead to long-term health risks that include type 2 diabetes, obesity, kidney problems and heart-related issues like high blood pressure, heart disease and stroke.
Lack of Sleep in Children
If children don’t sleep enough, it will likely manifest itself in other ways. This can include frequent misbehavior, hyperactivity, reduced concentration or performance in school, mood swings and tantrums and problematic social interactions.
This is extremely important for parents to know because if children of any age aren’t getting the requisite number of hours of sleep each night, their grades can suffer, and they may also experience certain behavioral issues.
At the same time, always remember that the number of hours a child needs depends on their age as well as on the individual child, so trying to force them to sleep for an arbitrary number of hours every night may be counterproductive.
How Can You Tell if You’re Not Getting Enough Sleep?
So by now, it should be clear that “six hours” is only a guideline, and that the exact number of hours an individual needs can vary depending on the person as well as on their age – although for most people, sleeping only six hours per night will leave them sleep deprived.
This means it’s important to establish whether you are getting the amount of sleep your body requires each night.
Surprisingly, though, it can often be quite difficult to judge whether we’re sleeping enough hours – or if the quality of sleep we’re getting is good enough – because we don’t remember how long it took to fall asleep and we might not remember waking up during the night.
That said, if you often feel drowsy during the day or you suffer from any of the symptoms we’ve discussed above, it can be a clear indication that you’re not getting enough shuteye.
Six Hours a Night Is Not Sustainable for Most People
If you think you might be suffering from a lack of sleep, you should try to be as objective as possible when assessing your possible symptoms because not meeting your body’s sleep requirements can lead to serious physical and mental health issues.
Try not to see a lack of sleep as something to be proud of that reflects how hard-working you are, and instead, try to sleep for the number of hours your body tells you it needs. Because for most people, sleeping only six hours a night is not sustainable in the long run.