How Much Sleep Do We Really Need In Order for Our Brains to Function Optimally?

In today’s fast-paced world, more and more individuals have gotten so used to scrimping on sleep. With plenty of work to do or dinner meetings to attend, some people just inadvertently push themselves to the limit, completely overlooking the utterly undesirable effects of sleep deprivation: tired eyes and clouded thinking, among many others.

For you to be able to function properly either at work or in school, you need to make it a habit to get a good dose of Zzzs. However, the question is, how much sleep do we really need in order for our brains to function optimally? Here are the answers according to experts.

How Much Sleep Is Enough?

Unfortunately, there is no such thing as “exact figure” when it comes to optimal amount of sleep, according to experts from the Harvard University Medical School. Different age groups have varying needs for sleep time. While some numbers are recommended (stated below), an exact figure cannot be established because some factors, like a person’s basal sleep need and sleep debt, need to be considered. Basal sleep refers to how much sleep an individual requires on a regular basis; while sleep debt refers to the amount of sleep an individual did not obtain or fell short of.  The latter is usually caused by accumulated interruptions from one’s slumber every now and then.

Recommended Sleeping Times

There is an expected variation in the needed sleep time because of the fact that sleep is “individualized,” which means it varies from person to person. According to Harvard Medical School Division of Sleep Medicine (DSM), the two factors that affect every individual’s amount of sleep are genetics and age. A person’s genetic make-up not only influences the amount of sleep he needs, but also his inclination to a certain sleeping pattern and waking time, or his preference to perform activities at different times of the day. According to Helpguide, a non-profit organization managed by psychotherapists, a very small percentage of the population (about 3%) has a genetic trait that makes the individual require only 6 hours of sleep and still be able to function optimally.  For the majority of the population, however, an adult needs 7.5 to 8.5 hours of sleep per day or per 24 hours.

Customarily, age is inversely proportional to the amount of sleep needed by an individual. Teenagers (ages 10 to 17 years old) should get 8.5 to 9.25 hours of sleep time every night for optimum brain performance at school. School-age kids, aged 5 to 10 years old, should get 10 to 11 hours of sleep every night. As for preschoolers aged 3 to 5 years, they should be left asleep for 11 to 13 hours. 12 to 14 hours are recommended for toddlers aged 1 to 3 years old, while infants need 14 to 15 hours of slumber time. Infants have the highest need for sleep time: 12 to 18 hours every day.

  • Newborns (1 to 2 months) – 10.5 to 18 hours
  • Infants (3 to 11 months) – 10 to 14 hours
  • Toddlers (1 to 3 years) – 12 to 14 hours
  • Preschoolers (3 to 5 years) – 11 to 13 hours
  • School-aged children (5 to 12 years) – 10 to 11 hours
  • Adolescents (12 to 18 years) – 8.5 to 9.5 hours
  • Adults (18 years to the end of life) – 7.5 to 8.5 hours

Can We Get Too Much Sleep?

Yes, we can. However, according to Daniel Kripke, co-director of research at the Scripps Sleep Center, a long sleep time – beyond 9 hours – is just as risky as short sleep ( below 5 hours). In his interview with Time Magazine, he asserted that long sleepers are at risk of suffering from depression, obesity, and consequently heart disease.

Long sleep is considered bad, but short sleep is worse. According to the National Institute of Health, lack of sleep can lead to a shortened attention span, dull memory, and higher BMI. It can also increase one’s risk of contracting heart conditions and diabetes, as well as running into vehicular accidents. As if that wasn’t enough, studies have shown that those who sleep both marginally and excessively suffer from a higher mortality rate, according to the US Department of Health and Human Services.

It has been proven time and again that sleep is crucial for survival. It basically allows your brain to “recharge” and pay attention to your internal systems, which are constantly functioning as you go along your day-to-day activities. But since too much and too little sleep have been seen to cause a variety of conditions, it is highly recommended for an individual to get just the right amount of it every day.

Here are some more articles of ours related to sleep:

 The sleep cycle explained
 How sleep affects learning
 Lack of sleep affects over 700 genes
 Is too much sleep bad for you?


If you need help tracking your sleep so you can optimize your sleeping pattern to wake up refreshed, try this Fitbit One Wireless sleep tracker.

About the author

EE Edit@rs

1 comment
Click here to add a comment