How Many Hours Of Sleep Are Enough?

Written by Beth Holloway, RN, M.Ed and medically reviewed by Ioannis Koutsourelakis, MD, MSc, PhD
2021-11-02

Many people wonder whether or not they’re getting enough sleep. Over the years, the amount of sleep considered too little, too much, or just right has changed. The National Sleep Foundation currently recommends 7 to 9 hours per night for healthy adults.

You may wonder why the National Sleep Foundation determined a recommended range of sleep duration - i.e. 7 to 9 hours, instead of 7 or more. Actually, healthy adults should not regularly have more than 9 hours of sleep. Just as there are health risks associated with too little sleep, there may be risks associated with too much sleep. When you ask  “How many hours of sleep is sufficient?” - part of the answer is “Not too little,” but part of it is “Not too much”.

The next question that comes to mind, “Are we getting sufficient sleep?” The 2017 National Health Interview Survey (NHIS) of almost 400,000 adults in the U.S., found over one-third of respondents had 6 or fewer hours. Since the last survey in 2004, the number increased by 15%; black and Hispanic adults had, by far, the largest increase in short sleep. 

How Much Sleep Do You Need? 

Sleep requirements are primarily based on age. For those who are healthy (illness may increase the amount of sleep needed) experts recommend the following sleep duration (in hours per day) by age:

  • Newborns to infants: 12-17 hours, including naps

  • Toddlers to preschoolers: 10-14 hours, including naps

  • School-aged children: 9-11 hours

  • Teenagers: 8 to 10 hours 

  • Young adults and adults: 7-9 hours

  • Older adults: 7-8 hours

Your sleep quantity, or duration of sleep, is important, but so is your quality of sleep. In general, good sleep quality means: you fall asleep easily, you stay asleep, and you wake up feeling well-rested.

How Were The Recommendations Created?

Top medical organizations develop guidelines for use by practicing physicians and other healthcare providers, think about the American Diabetes Association (ADA) or the American Academy of Pediatrics (AAP). A group of experts within the organization conduct a thorough review and analysis of medical studies on a particular topic. From there, they work together to establish guidelines.

This is the way that the National Sleep Foundation’s expert panel determined their recommendations for sleep quantity for each age group.

What Are The Symptoms of Too Little Sleep?

Think about the last time you didn’t get enough sleep. These symptoms may sound very familiar. The next day, it is common to have some of the following:

  • Sleepiness

  • Irritability

  • Headaches

  • Low energy

  • Poor motivation

  • Decreased brain functioning

    • Trouble concentrating

    • Difficulty remembering

    • Trouble completing tasks

What Are The Health Risks of Too Little Sleep?

A quick look through the research on the topic “short sleep duration and health risks” reveals dozens of studies - none of them with positive results. Short sleep is associated with many health problems. In fact, sleep has such an impact on overall health and well-being, so much so that the lack of sleep has the opposite effect - it is generally associated with poor health. 

The following are linked to poor sleep:

Are Five Hours Of Sleep Adequate? 

The quick answer? “No!” Neither is 6 or even 7 hours. Having a short amount of sleep once in a while won’t hurt you, although you may have trouble with work or other activities the next day. However, fewer than 7 hours of sleep on a regular basis is harmful to most people. Just look at some of the health risks and you’ll realize the implications of too little sleep.

What Is A Short Sleeper?

A very small number of people are “short sleepers,” they sleep less than 6 hours, or even less than 4 or 5 hours every night, without trying. Scientists have actually identified rare gene mutations in those requiring short sleep. 

Even with less than the recommended 7 to 9 hours of sleep, they wake up feeling refreshed and do not have the usual symptoms of too little sleep.

Can You Train Yourself To Sleep Less?

You may want to sleep less than 7, or even 5, hours in order to get more done. You can try, but it will begin to affect your mind and body quite quickly. 

Generally, short sleepers are very uncommon. Trying to sleep less may work in the short-term, but over time you will accumulate a “sleep debt” or “sleep deficit” or “chronic sleep deprivation.” For example, you may miss an hour of sleep most nights, watching late-night television or checking email, however, over a week that’s up to 7 hours less sleep than you need. Even though you may not feel tired and may get used to sleeping less, in the long-term, it impacts your ability to function well

Another study, a 30-day analysis of short sleep, found problems with attention and alertness, as well as reaction time. One of the researchers remarked, "People cannot learn to live on insufficient sleep and they may not be aware of their reduced cognitive abilities.” 

Why Don’t People Get Enough Sleep?

Take a moment to think about the reasons you don’t get adequate sleep, they’re probably similar to everyone else. There are many reasons, some of them from the American Academy of Sleep Medicine (AASM). They include:

  • Trying to sleep less. The discussion above explains this reason and its consequences

  • Family and home life. For example, taking care of your children or other loved ones, or household responsibilities

  • Work or school. For example, long hours or shift work, commuting, or studying

  • Sleep problems. Short sleep is only one of the problems. Others are poor sleep quality, sleep apnea, and movement disorders, like restless legs syndrome

  • Health. For example, having conditions like pain, breathing problems, depression, anxiety, or others

  • Lifestyle. Your diet, timing of eating, and exercise level are examples

  • Substances. Having drinks with alcohol or caffeine or smoking

  • Medicines. Taking certain prescriptions, over-the-counter (OTC) products, and supplements

  • Activities. You may stay awake to read, watch television, or take part in social activities

What Are Some Tips For Better Sleep?

Have you heard of the term, “sleep hygiene?” It refers to measures to help you sleep better and includes your sleep environment and daily activities. In general, it’s best to go to sleep and wake up at about the same time every day, including weekends. It also helps to take some time to relax before going to sleep - it’s a nice transition from daytime stressors.

Your Sleep Environment

Your bedroom and bed should be comfortable, cool, dark, and quiet - the optimal environment for sleep. Discomfort like being too warm, light shining in your eyes, or noise from another room, make it challenging to sleep. 

Use of electronic devices delays and interferes with sleep. It may be difficult, but you should avoid your phone, laptop, and television close to bedtime. Instead, deep breathe or meditate, read a book, talk to your housemate, or write in a journal.

Your Daily Activities

Making some changes or avoiding the activities that interfere with sleep, can help you get better sleep. 

Health Problems

Some medical conditions can make it hard to sleep. Painful musculoskeletal conditions, like low back pain, can keep you awake. Breathing problems make it difficult to sleep, asthma, for example, may be worse at night. Lying down when you have gastroesophageal reflux (GERD) or reflux makes the symptoms worse. The same is true for problems with your emotional health. Both depression and anxiety often interfere with sleep.

Talk with your doctor if you have any of these problems (or symptoms of any of them) or if you have trouble sleeping and don’t know why. In either case, they can provide care.

Medicines, OTC Products, and Supplements

Talk with your doctor about your medicines, including OTC products and supplements. It’s possible that they may make it difficult to sleep. 

Your doctor may choose another prescription, change the dose, or time you take it. For example, some medicines can be taken earlier in the day if they’re interfering with your sleep.  Don’t make any changes without first discussing it. The same is true for OTCs and supplements - your doctor may recommend changes.

Manage Diet, Exercise, And Alcohol

What you eat and when you eat may cause trouble with sleep. Avoid eating foods that cause indigestion as well as large meals or snacks near bedtime.

Caffeine interferes with sleep in most people. It’s best to avoid all caffeine after lunchtime.

One of the benefits of exercise is improved sleep. Make sure you’re active everyday. You might avoid exercise near bedtime, if it interferes with your sleep.

It may seem like alcohol helps with sleep - it does cause drowsiness, however it also interferes with the quality of your sleep. If you do have a drink, it’s best to have it with dinner - 3 to 4 hours before you go to bed.