How Much Sleep Do You Need? Calculate The Ideal Amount

woman sleeping in bed

For me personally, seven hours of good quality sleep seems to be the golden ticket. If I hit eight hours, I might even smile and say good morning to strangers. Less than six hours and those same people might wonder if the smiley one has a grumpy twin.

Perhaps for you, the ‘magic number’ to feel refreshed could be six or nine hours. And that’s right now – maybe a few years ago your sleep looked completely different.

The thing is, the amount of sleep we need changes as we age, and as different factors affect us, such as our health, diet or medication. Even two people with similar circumstances on paper might sleep very differently because of their genetics or other hidden factors.

Factors that influence how much sleep you need:

  • Age
  • Health
  • How physically and mentally active you are
  • Diet and other lifestyle choices
  • Genetics
  • Sleep quality

So how do we really know how much time spent blissfully asleep is best for us?

It would be great if we could rely on instinct alone, and maybe we can with the help of a little self-observation. But in the busy modern world, many people choose to sacrifice sleep for work or their social life; others might wish they could sleep more, but simply don’t feel they have a choice.

Three kids and a mortgage to pay? Sleep – what’s that?!

So if you’re not sure how much sleep will work for you or if you have a nagging feeling that you get too little or too much sleep, it might help to start with the guidelines that sleep experts have.

Equally, we’re all different. So along with the broad expert advice, it’s good to work out how much sleep you personally need to thrive. And I’ll look at how to do that later in this article.

National Sleep Foundation Guidance based on age

In 2015, the National Sleep Foundation produced detailed guidance on the ideal sleep duration for different age groups.

The foundation brought together a team of 18 sleep experts from a range of fields. And they analyzed over 300 research studies to assess the ideal sleep times. So it’s not hard to see why many websites still refer to their guidelines when talking about sleep times.

For each age bracket, they have three defined total sleep times:

  • Recommended
  • May be appropriate for some individuals
  • Not recommended

So it’s interesting that although they published recommended sleep durations for different ages, they acknowledge that there are exceptions. For example, although most adults under the age of 65 probably need seven to nine hours, the genes of a small number allow them to do just fine on six.

Here are their recommendations by age:

Newborns (0-3 months)

  • Recommended: 14 to 17 hours
  • May be appropriate: 11 to 13 hours / 18 to 19 hours
  • Not recommended: Less than 11 hours / more than 19 hours

Infants (4-11 months)

  • Recommended: 12 to 15 hours
  • May be appropriate: 10 to 11 hours / 16 to 18 hours
  • Not recommended: Less than 10 hours / more than 18 hours

Toddlers (1-2 years)

  • Recommended: 11 to 14 hours
  • May be appropriate: 9 to 10 hours / 15 to 16 hours
  • Not recommended: Less than 9 hours / more than 16 hours

Preschoolers (3-5 years)

  • Recommended: 10 to 13 hours
  • May be appropriate: 8 to 9 hours / 14 hours
  • Not recommended: Less than 8 hours / more than 14 hours

School-aged children (6 to 13 years)

  • Recommended: 9 to 11 hours
  • May be appropriate: 7 to 8 hours / 12 hours
  • Not recommended: Less than 7 hours / more than 12 hours

Teenagers (14 to 17 years)

  • Recommended: 8 to 10 hours
  • May be appropriate: 7 hours / 11 hours
  • Not recommended: Less than 7 hours / more than 11 hours

Young adults (16 to 25 years)

  • Recommended: 7 to 9 hours
  • May be appropriate: 6 hours / 10 to 11 hours
  • Not recommended: Less than 6 hours / more than 11 hours

Adults (26 to 64 years)

  • Recommended: 7 to 9 hours
  • May be appropriate: 6 hours / 10 hours
  • Not recommended: Less than 6 hours / more than 10 hours

Older adults (65 years and over)

  • Recommended: 7 to 8 hours
  • May be appropriate: 5 to 6 hours / 9 hours
  • Not recommended: Less than 5 hours / more than 9 hours

How to work out the ideal sleep time for you personally

The sleep times guidance based on age is a useful starting point. But how can an adult be sure if six, eight or ten hours is right for them?

There’s a big difference between six and ten hours, especially as the years roll by. So it’s useful to work out how much sleep you personally need. And that means considering two questions:

  • How much sleep is enough to just get through the day?
  • How much do you need to function at your best and be happiest?

The answer to these two questions could be quite different. For example, you may think that you can scrape through the day if you’ve had six hours’ sleep.

But is six hours enough to work efficiently and be in a good mood all day? Or does it turn you into a coffee fiend or a grumpy thing like me?

Keep a manual sleep diary

image of a woman writing in her diary

A useful way to work out your optimum sleep time is to keep a sleep diary. In your diary, you can record four points each day:

  • The time you fell asleep.
  • The time you woke up.
  • How much total sleep you believe you had.
  • How you felt the next day.

For the time you went to sleep, try to approximate when you fell asleep, not when you went to bed. It might be difficult if you’re restless in the dark for some time, but try to be as accurate as you can.

Look for patterns in your sleep and daytime functioning

After a couple of weeks, it’s time to analyze your diary for patterns. If you felt alert, energized, and able to do things well all day long, you probably slept enough the night before.

But if you felt any of the symptoms of sleep deprivation, you might not have gotten enough the night or two before.

You can continue doing this for as long as you like. And over the weeks or months, you’ll get a clearer picture of the amount of sleep you need to aim for.

If you want more accurate information over a period of time, you could invest in a good sleep tracker. But it’s still a good idea to keep a manual diary of how you felt each day.

Sleep deprivation symptoms to watch out for

It’s possible to experience symptoms of sleep deprivation without even realizing it. So when you complete your sleep diary, keep an eye out for these signs:

  • Always needing an alarm clock to wake up, or hitting snooze a lot.
  • Finding it mentally difficult to get out of bed.
  • Feeling sleepy at work, school, or in warm environments.
  • Feeling very tired after a heavy meal, in the afternoons, or when driving.
  • Being grumpy or irritable.
  • Having difficulty concentrating, remembering things, or making decisions.
  • A change in appetite or weight gain.
  • Being more accident-prone.
  • It only takes you a couple of minutes to fall asleep at night.
  • Susceptible to colds and infections.
  • Stressful things are difficult to cope with.
  • Finding it hard to motivate yourself to do normal activities.
  • Your reaction times are reduced.
infographic explaining key sleep deprivation symptoms

There may be other explanations for some of the above points. But it’s still important to record them in the context of observing how you feel after different amounts of sleep.

The key is to carefully check your diary to see if you only experience the symptoms on the days after having less sleep. That will be a good indicator that you’re not getting enough sleep on those days.

And hopefully, you’ll also start to see much sleep leads to the words ‘felt awesome!’ appearing in your diary.

Don’t panic if you’re not sleeping enough

Even though these guidelines exist, try not to panic if you don’t always get that optimum amount.

For example, if you’ve worked out that eight hours is what you need to wake up feeling great, then the temptation will be to worry when you only get seven.

The reality is that most people can function well with less sleep from time to time. So on the nights when it takes you longer to fall asleep, try not to worry that the next day will be difficult. That thought will only keep you awake longer.

How much do you sleep?

How much sleep do you think you get on average, and how much do you think you need to be at your best? Let me know in the comments below!

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