How many hours of sleep do you need?

How many hours of sleep do you need?

For many people, falling asleep is their favorite part of the day. In addition to being satisfying, sleep benefits your health, allowing the body and mind to rest and recharge.

Some people sleep a lot, others don’t sleep as much; some people fall asleep from the moment their head touches the pillow, while others take a little more time to nod off. Every human being is different, so we can't all have the same sleeping experience; be it down to family genetics or personal lifestyle, various factors can affect both your need for sleep and your sleep-wake cycles, meaning the body has to adapt to the needs of every individual.

The recommended hours of sleep for each person therefore also differ greatly, and are based heavily on the stage of life, age being one of the most significant factors.

For example, a four-year-old experiences intense physical and mental activity. Everything is highly stimulating, meaning sleep needs to be restful and last longer than for an adult or teenager, while more mature people, particularly over age 65, have less reliance on sleep.

Unfortunately, there is no tried and tested way to know for sure how many hours of sleep you need.

Every person benefits from a specific number of hours and there is a whole host of factors to consider when it comes to working out that sweet spot.

How can we work out how many hours of sleep we need?

We have all found ourselves forced at some point in our life to lose some hours of sleep, perhaps because of a hungry newborn, the stress of a particularly intense time at work, or because of last-minute cramming before the final exam of the school year. When we get fewer hours of sleep that we would like, it can seem as though everything takes much more effort than usual and we can physically feel the call of the bed throughout the day.

For the body, deep sleep is much more than simply a way to recharge your batteries; while we sleep, our body takes the time to reset, to produce substances we need for our metabolism and immune system so we can regenerate, and to store memory traces in the cerebral cortex. When we wake up after a deep sleep, we feel more energetic, calm and as though we can take on the world.

If we don’t get enough hours of sleep during our nightly “pit stop”, we can feel a lack of energy and difficulty concentrating, causing the whole next day of working or studying to go down the drain.

On the flip side, however, there is a limit to how much we should sleep; sleeping for too many hours can be as counterproductive as sleeping for too few hours.

Along with the hours of rest we get, there are two fundamental requirements to getting healthy sleep: on the one hand, the quality of sleep needs to be good, without any interruptions; on the other hand, the amount of sleep we get needs to be right for our body.

So, the real question is, how many hours do you need to feel healthy and well-rested? Although there is no one-size-fits-all when it comes to sleep, we can analyze various factors that can help to give us a good idea of how many hours of sleep we need.

How many hours of sleep are needed at different ages?

To find the answer to such a specific question, we can turn to science and research. Based on global studies conducted over more than two years, the National Sleep Foundation offers some general up-to-date guidance on the recommended hours of sleep we need by age and the needs of the human body at each stage of life.

The results of this large-scale study recommend getting the following recommended hours of sleep for each age range:

  • Newborns (0-3 months): the current recommendation is 14-17 hours a day.
  • Babies (4-11 months): the current recommendation is 12-15 hours.
  • Young children (1-2 years): the current recommendation is 11-14 hours.
  • Pre-school children (3-5 years): the current recommendation is 10-13 hours.
  • Elementary-school children (6-13 years): the current recommendation is 9-11 hours.
  • Teenagers (14-17 years): the current recommendation is 8-10 hours.
  • Young adults (18-25 years): the current recommendation is 7-9 hours.
  • Adults (26-64 years): the current recommendation is 7-9 hours.
  • Mature adults (65+): the current recommendation is 7-8 hours.

On the basis of this brief outline, an adult would struggle on 5 hours of sleep a night, an adult should ideally sleep between 7 to 9 hours to feel rested and productive the following day, and especially to avoid any health issues associated with a prolonged lack of sleep.

The scale provided for each age group emphasizes the individualized need for sleep. We do therefore recommend that everyone evaluate the hours of sleep they would most benefit from based on their own individual needs; we can do this by paying attention to how we feel after a certain number of hours of sleep.

Individual needs and recommended hours of sleep

Aside from age, we also have to consider genetic factors, which are unchangeable and significantly impact how many hours of sleep we need, as well as when we tend to fall asleep and, in general, how we feel when we don’t get enough sleep.

For example, someone over 65 years old may feel the need to fall asleep between 9 p.m. and 10 p.m., subsequently waking up between 4 a.m. and 5 a.m. You might think this doesn’t sound like a healthy sleep pattern, but in actual fact it would give the body the exact amount of sleep it needs.

Our sleep cycle is also affected by light and darkness. In well-lit conditions, our body produces more of a hormone called cortisol, which keeps us alert, while it produces less of the hormone melatonin. Vice versa, in the dark, our brain produces more melatonin, which affects our sleep by reducing the time it takes us to fall asleep.

Many students choose to study at night, which gives them a false sense of relaxation, also thanks to the absence of noise and the feeling as though time slows down. In reality, a good night's sleep is vital for memorizing information that we learn during the day, meaning going to bed at an appropriate time would be a much more effective use of a student’s time, allowing them to rest well and have the energy they need to take on the next day of learning.

We therefore recommend studying in the morning, and between midday and 4 p.m. or 5 p.m. in the afternoon, because these are the hours when the brain is most ready to receive information. As the day goes on, it becomes more difficult to take in and store information.

As we have already considered, the quality of sleep we get is another very important factor when it comes to working out the ideal hours of sleep we should enjoy. If the quality of sleep we experience is poor, we may need more hours of sleep compared to the range recommended based on the study.

Our sleep cycle is therefore another factor to bear in mind when we want to figure out how many hours of sleep we need.

How many hours of deep sleep do we need each night?

Our sleep is led by our own individual biological clock, but there is a general sleep cycle that is common to everyone, which is divided into various phases.

Non-REM sleep is divided into 3 stages:

  • stage 1: falling asleep, which lasts on average 7 minutes.
  • stage 2: light sleep, which takes place in the first hours following falling asleep.
  • stage 3: deep sleep. This stage and the following phase of sleep are the most beneficial to the body and usually account for 20-30% of sleep in total.

REM sleep occurs for the first time about 90 minutes after falling asleep and repeats at longer and deeper intervals during the second half of the night, alternating with non-REM sleep throughout the night.

On average, we experience 1 hour and 40 minutes of deep sleep each night, in cycles lasting around ten minutes that repeat from four to six times. Deep sleep tends to occur at the beginning of the night until around 4 a.m.

Deep sleep has the biggest impact on our quality of sleep, is essential for our brain to function properly, contributing to storing memories, and is vital for our immune system.

Hours of sleep and productivity at work: Chronotypes

Research has highlighted how important it is to get the right number of hours of good-quality sleep if we want to work efficiently the following day. People who suffer from insomnia or do not get enough good-quality sleep tend to be less productive and more at risk when it comes to occupational health and safety; this appears to be related, at least in part, to a decrease in our ability to make full use of the mental and physical capacities that our work requires.

A lack of sleep impairs work skills that we often need to call upon these days, such as result orientation, problem solving and lateral thinking.

So, what can we do? If you didn’t get enough shut-eye before the birds start chirping, if you got only a few hours of bad-quality sleep and you would quite like to hit snooze with a hammer when your morning alarm rings, or if it feels as though everyone else in the office has been set to fast forward while you’re working in super slow motion… research is here to help! A restorative afternoon nap, even for just a few minutes (but no longer than 20 minutes, to avoid falling into a deep sleep), can help to improve your cognitive functioning and ability to pay attention, reducing the feeling of tiredness and drowsiness during the day. Instead of your usual lunchtime sandwich, it could be worth trying a piece of the power-nap pie!

In addition to whether you get the recommended hours of sleep or not, work productivity is impacted by when you sleep. We are not all built in the same way; there are two different “chronotypes”, or two circadian rhythms that structure when we sleep best and are most productive throughout the day.

“Early birds” are people who naturally tend to go to sleep early and wake up early. These people are most productive in the morning and are tired out by the afternoon.

“Night owls” are people who tend to stay awake for longer at night and wake up later. For these people, an early morning would be a real nightmare, because they don’t mentally wake up fully until around lunchtime.

Where your work allows, it is important to follow your own rhythm. For example, you should try to tackle more complex tasks or save the most challenging topics to study and analyze for the times when you feel the most mentally alert, meaning you can make better decisions, solve problems more quickly and maximize your talent.

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Disclaimers:

  • Dietary supplements are not intended to substitute a varied and balanced diet and should be taken as part of a healthy lifestyle.
  • Melatonin contributes towards reducing the time it takes to fall asleep.