How Much Sleep Do You Actually Need & Is It Bad To Get Too Much?
Lack of sleep doesn't just leave you feeling tired the next day; it has long-term effects, including increased risk of chronic diseases, obesity, and overall mortality risk1, to name a few.
Yet, so many of us still fail to get as much sleep as we need. According to the CDC, more than 35% of U.S. adults are getting insufficient sleep2 (which the CDC defines as less than seven hours). And almost 12% of Americans are getting less than five hours a night.
But how much sleep do you actually need? And how bad is it really to not get enough? Here's what you need to know.
The recommended amount of sleep.
According to the National Sleep Foundation (NSF), the amount of sleep you need varies with age, with newborn infants needing the most and older adults needing the least.
The NSF sleep guidelines were developed by an independent team, which performed a systematic review of the available medical literature. A panel of 12 medical organizations and six experts then reviewed the findings and created these age-specific recommendations3:
- Newborns (0 to 3 months): 14 to 17 hours (with naps)
- Infants (4 to 11 months): 12 to 15 hours (with naps)
- Toddlers (1 to 2 years): 11 to 14 hours (with naps)
- Preschoolers (3 to 5 years): 10 to 13 hours (with naps)
- School-age (6 to 13 years): 9 to 11 hours
- Teenagers (14 to 18 years): 8 to 10 hours
- Young adults (18 to 25 years): 7 to 9 hours
- Adults (26 to 64 years): 7 to 9 hours
- Older adults (65-plus years): 7 to 8 hours
What happens when you don't get enough sleep?
Sleep isn't just a time for your body to rest; it's important to allow your body to recover and repair. Getting less than the recommended seven to nine hours of sleep4 for adults is associated with an increased risk of obesity, diabetes, high blood pressure, heart disease, stroke, and even mental health issues.
The body goes through five stages of sleep, progressing from light sleep in Stage 1 to deeper sleep in Stage 4 and REM sleep at Stage 5, when dreaming happens. It's not until Stage 3 that repair really starts to kick in. Clinical psychologist and board-certified sleep specialist Michael Breus, Ph.D., explains, "We see a physical restoration during sleep Stages 3 and 4. This is where the bulk of growth hormone is produced, and we see the body repairing itself."
Sleep is also important for developing memories, Breus adds: "During REM sleep, we move information from short-term memory to long-term memory and create an organizational sub-structure to recall, and problem-solve," which may explain why lack of sleep is associated with cognitive decline5.
In addition, the brain's waste removal system, the glymphatic system, works to "wash" your brain while you sleep. Neurologist Ilene Ruhoy, M.D., Ph.D., explains that this process removes the precursors to inflammation, allowing for brain restoration and rejuvenation to take place.
If you aren't getting enough sleep, or good-quality sleep, these processes don't have a chance to happen, potentially leaving you at risk for chronic diseases and cognitive decline.
Can you get too much sleep?
More isn't necessarily better, though. Studies have also found that sleeping too many hours can potentially be harmful.
Excessive sleep is associated with health issues such as type 2 diabetes, heart disease, obesity, depression, headaches, and increased risk of dying from any condition. It should be noted, however, that it's not known whether oversleeping causes these conditions or if it is simply a symptom of an already existing condition.
How to know if you're getting the right amount of sleep.
According to Lawrence J. Epstein, M.D., program director, Sleep Medicine Fellowship Program, Brigham & Women's Hospital, the exact amount of sleep needed will vary by individual. While the average range is seven and a half to eight and a half hours, the exact amount varies. It could also be more like nine to ten or five to six hours. What is important is determining what is the right amount for you.
To learn the correct amount for you, Epstein recommends testing it out at a time when you are able to sleep as much as you'd like, without an alarm clock, for example, or when you are on vacation. At first, says Epstein, you will probably sleep more as you make up for whatever deficit you might have. After a few days, however, you will settle into a pattern of sleeping a consistent amount of time. This is the amount of sleep that you personally need.
According to Epstein, you will know that this is the correct amount of sleep for you if you are waking up feeling rested and restored.
Getting enough sleep is important to our health and well-being. Too little sleep over time can lead to both physical and mental health issues. However, too much sleep might also be a sign of trouble.
It is important to get enough sleep for your personal needs, whatever they may be. But if you are having trouble getting the right amount of good-quality sleep, don't hesitate to see your health care provider for assistance.
Nancy Schimelpfening, M.S., earned her master's degree in Community Health Education from Old Dominion University.
She is a freelance writer and president of Depression Sanctuary, a non-profit organization that offers free support to those suffering from depression and other mental illnesses. She lives in San Antonio, TX.