What is the Ideal Amount of Sleep for Good Health?


Can lack of sleep affect your health

Lack of sleep – You can’t pick up a magazine or turn on the television these days without reading or hearing about the importance of getting enough sleep. No wonder! A good night’s sleep gives your body the downtime it needs for recuperation and rejuvenation.

When you think about it, you spend almost a third of your life sleeping, so slumbering must be important for health. Although we know sleep is essential, it’s debatable how much sleep we really need for optimal mental and physical well-being. Sleep requirements also vary with age. For example, it’s not unusual for newborns to sleep 12 or more hours a day – but what about adults? You’ve probably heard people say that eight hours a night is ideal for health – but is it really?

What’s the Purpose of Sleep? 

You might wonder why we spend a substantial chunk of our lives with eyes closed, unconscious of the world around us? For your body to have evolved to need sleep, it must serve a vital function – and it does.

While you’re sleeping, your body doesn’t completely shut down, although your metabolism and many of your bodily functions slow. One theory as to why you sleep is to give your body time to repair and restore. Indeed, there is evidence of this. It’s during deep sleep that your brain releases growth hormone, a hormone that stimulates muscle protein synthesis and promotes bone growth.  While you’re sleeping, the hormones that control so many bodily processes are still busy at work, helping your body repair.

Another theory as to why we sleep has to do with memory consolidation. When you drift off to sleep at night, the nerve cells in your brain are still active. Scientists believe that during this time, nerve cell connections reorganize in a way that strengthens learning and memories. The information you learned prior to falling asleep is transferred to the cerebral cortex, a high capacity storage center. So, getting enough sleep enhances your ability to remember what you learned the previous day.

As you can see, you need sleep for physical restoration and rejuvenation and for boosting memories and mental function. Plus, there’s growing evidence that not giving your body enough downtime can harm your health. A number of studies have shown a link between lack of sleep and a higher risk of chronic health problems, including heart disease, type 2 diabetes, as well as a jump in overall mortality. Lack of Sleep may also increase your risk of dementia and other neurodegenerative diseases.

How might lack of sleep contribute to dementia? Research shows our brains accumulate toxins when we’re awake. One of these toxins is a beta-amyloid, a protein that builds up in the brain in people who have Alzheimer’s disease. When we sleep, our brain eliminates these toxins through a special component of the lymph system called the g-lympathic system. If you don’t get enough sleep, these proteins can build up. Lack of sleep impacts brain function in a number of ways – by effects on memory and by depriving your brain of the time it needs to house clean.

Lack Of Sleep: Is Eight Hours of Sleep Still Best? 

Now that you have a better idea of why you sleep, what is the optimal amount? As you might expect, sleep requirements vary by age. Children need more sleep than older adults since their cells are dividing rapidly and need more time for repair and restoration. In a study published in the journal Sleep Health, a panel of experts reviewed the evidence and delivered the following recommendations:

·       Newborns, up to 3 months of age 14-17 hours daily.

·       Infants (4-11 months) 12-15 hours daily.

·       Toddlers (1-2 years): 11-14 hours daily.

·       Preschoolers (3-5): 10-13 hours daily.

·       School-age children (6-13): 9-11 hours daily.

·       Teenagers (14-17): 8-10 hours daily.

·       Younger adults (18-25): 7-9 hours daily.

·       Adults (26-64):  7-9 hours daily.

·       Older adults (65+): 7-8 hours daily


You might assume that more sleep is better, but not necessarily. In fact, the optimal amount of sleep for an adult seems to follow a u-shaped curve. Sleeping 7 to 9 hours a night is linked to a lower risk of health problems, relative to sleeping less than 6 hours a night or more than 10 hours nightly.

What type of health problems is a lack of sleep linked with? Heart disease, stroke, obesity, and type 2 obesity. Another study found that men and women who slept less than 6 hours a night were 20 to 32% more likely to develop hypertension. There seems to be a sleeping “sweet spot” at around 7 to 9 hours a night that’s optimal for the average person.

It looks like you CAN get too much of a good thing, including sleep. What’s not clear is whether sleeping too much is problematic or whether people who sleep longer have comorbidities, like depression or general bad health already that causes them to sleep longer. In other words, sleeping longer may be a marker for generalized bad health.

Based on the current research, the general consensus is that adults should sleep around 7 to 7.5 hours nightly. What this doesn’t take into account are factors like stress, degree of physical activity, and health factors that might increase the need for quality sleep. We’re all a little different.

Sleep Quality Matters Too 

What some studies fail to take into account is sleep quality. As you might have guessed from all the commercials about sleep aids, many people have problems falling asleep and staying asleep. Plus, insomnia becomes more common with age. If you toss and turn most of the night, does that really count as sleep? Your body repairs and rejuvenates during the deep stages of sleep and if you have poor quality sleep you may not spend as much time in the deeper stages of sleep. That’s when most of the growth hormone that aids in protein synthesis is released.

How’s YOUR sleep? Keep a sleep diary for a few weeks. If you find that you have sleep problems, address them with a health care professional. Sleep is too important not to get right. If your sleep quality isn’t the best, make changes to your habits and sleeping environment. Sometimes something simple like drinking caffeine too late in the day or taking certain medications may be the problem. If you consistently have problems sleeping, talk to your health care provider.



Scientific American. “Science Explains Why We Really Do Need to Sleep a Third of Our Lives Away”

The New Yorker. “The Work We Do While We Sleep”

Sleep Health. March 2015Volume 1, Issue 1, Pages 40–43.

Medcape Multispecialty. “U-Shaped Curve for Sleep Duration and Cardiovascular Disease”

News Medical. “U-shaped curve links sleep duration with chronic disease”

Sleep in Medical and Neurologic Disorders, an Issue of Sleep Medicine Clinics


Related Articles By Cathe:

How Does Lack of Sleep Affect Your Metabolism?

Sleep and Health: It’s Not Just the Amount of Sleep but the Amount of Deep Sleep

How Lack of Quality Sleep Limits Muscle Growth

Is It Normal to Have Sleep Problems As You Get Older?




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