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.  

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.

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.

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.

More isn't necessarily better, though. Studies have also found that sleeping too many hours can potentially be harmful. 

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.

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.