How much sleep do I need?

Dr. Alon Avidan, MD

If you are over age 18, you need about 7 to 9 hours of sleep. If you sleep less than 7 hours, you are probably at risk for sleep deprivation. If you are in the ages 12 to 18, you should probably get about 8.5 to 9 hours. Older adults need as much sleep as younger adults. The problem is that their ability to sleep often is disrupted. As a rule of thumb, 7 to 8 hours of sleep is essential. If you're getting less than 7 hours, you're probably setting yourself up for sleep deprivation.

Adults should sleep seven or more hours per night on a regular basis to promote optimum health.

Talk to your doctor if you are concerned about your sleep.

This content originally appeared on the American Academy of Sleep Medicine website.

Healthy sleep can be defined as the amount and quality of sleep that allow one to maintain optimal alertness while awake. Most adults need about eight hours of sleep each night, although sleep requirements vary somewhat among individuals. Children and adolescents typically need more than eight hours of sleep, but after age four, most children require little-to-no daytime sleep.

While sleep requirements vary slightly from person to person, most healthy adults need between seven and a half to nine hours of sleep per night to function at their best. Children and teens need even more. And despite the notion that our sleep needs decrease with age, older people still need at least seven and a half to eight hours of sleep. Since older adults often have trouble sleeping this long at night, daytime naps can help fill in the gap. The best way to figure out if you're meeting your sleep needs is to evaluate how you feel as you go about your day. If you're logging enough hours, you'll feel energetic and alert all day long, from the moment you wake up until your regular bedtime.

What is considered sufficient sleep for each person depends on factors including basal sleep need (the amount of sleep the body routinely needs to perform well) and sleep debt (the accumulated sleep lost to poor sleep habits, awakening during the night and other causes). The timing of a person’s sleep is also important. Shifting the bedtime by more than two hours each night may disrupt the circadian rhythm, or “internal body clock,” and cause difficulties falling asleep, staying asleep, waking up on time and feeling restored by sleep.

Generally, people require the following amount of sleep:

  • Newborns (1 to 2 months): 10.5 to 18 hours
  • Infants (3 to 11 months): 9 to 12 hours during night and 30-minute to 2-hour naps, one to four times a day
  • 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
  • Teens (11 to 17 years): 8.25 to 9.25 hours
  • Adults: 7 to 9 hours
Stacy Wiegman, PharmD
Pharmacy Specialist

The amount of sleep one needs changes as we grow and age, and may depend on your health and overall condition. Typically, adults need 7 to 8 hours of sleep. School-aged children need at least 9 hours, while preschool children need 10 to 12 hours of sleep. Newborn children must get at least 16 hours of sleep a day.

Most adult people need between seven and nine hours of sleep each night. This is an average, and is also subjective. You probably know how much sleep you will need in any average night to feel your best.

The amount of sleep you need does decrease with age. A newborn baby might sleep for 20 hours a day. By age four, that average becomes about 12 hours a day. By age 10, average sleep falls to 10 hours a day. Senior citizens often get by with six or seven hours of sleep a day.

Dr. Michael Breus, PhD
Psychology Specialist

The answer really depends on the individual, but there are some basic guidelines. While the sleep community says that between 7 to 9 hours of sleep is best, the data shows that there are many people who sleep well and wake refreshed after only about 6.5 hours or 7 hours. There is also data that shows that people who sleep more than 10 hours and less than 5 hours per night have a higher mortality rate. 

The thing to remember here is that it is not just about the quantity of sleep, but also the quality of the sleep you are getting. Sleep seems to come in waves of 80 to 120 minute cycles, and the average person needs 4 to 5 cycles to wake feeling refreshed. If your sleep cycle averages 90 minutes and go through 5 sleep cycles in one night, you will need about 7.5 hours of sleep. If your cycle is shorter you may require fewer hours of sleep.

While most adults need between 7 and 8 hours of sleep, some need as few as 6 and some as many as 9 hours of sleep each night. The general rule is that the amount of sleep a person needs is the amount that allows him/her to feel fully refreshed and alert all day long. The amount and kind of sleep a person gets changes with age. With age, some people start having trouble staying asleep, which can lead to a more interrupted night's sleep.

Dr. Carol Ash, DO
Pulmonary Disease Specialist
Getting enough sleep is a basic need of the body. In this video, Dr. Oz and Dr. Carol Ash discuss what can happen to the body if it doesn't get enough sleep.

Dr. Kathleen Hall
Preventive Medicine Specialist

Every system in your body is refreshed and restored each time you sleep. Healing occurs during our sleep cycles, so when you are ill or run down, honor your body's needs for more sleep. Listen to your body. Your body will tell you how much sleep you need. Practice awareness and respect the messages your body sends you. Don't try to force it into an artificial pattern that causes you to be chronically overtired. We have a seriously damaging cultural myth that people who sleep fewer hours are more productive and in some way more "successful," when in fact the opposite is really true. Well-rested people are more focused and efficient than the sleep-deprived.

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Everyone has a different sleep need. The eight hour rule is general, and not necessarily for those who can feel and actually be fully refreshed on fewer hours; those who don’t physically need at least seven or eight hours are known as short sleepers, but they are not the majority of the population. You could be fooling yourself to think you can get by on just four hours a night, especially in the long term. Sleep is not a luxury.

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Ms. Ashley Koff, RD
Nutrition & Dietetics Specialist

It's a myth that there's a magic number of hours the body requires to sleep. Everyone has a different sleep need. The eight-hour-rule is general, but not necessarily the ideal number for you. Most people need seven to nine hours, and chances are you know what your number is. If you feel like a drag after a six-hour night, then clearly you need to aim for more sleep. Think of the last time you went on vacation and slept like a baby for more hours a night than usual. That is probably your perfect number.

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You should sleep from seven to nine hours a night. Insufficient sleep increases the risk of developing diabetes, while sleep duration and quality have emerged as predictors of levels of Hemoglobin A1c, an important marker of blood sugar control. Less than six hours sleep a night raises the chances of colon cancer by 50 percent.
Dr. Dawn Marcus

Sleep needs change over a lifetime. You often hear people say that the older you get, the less sleep you need. That's only true when you're a child. Once you become an adult, you continue to need 7 to 8 hours of sleep each night—even as you grow older.

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Sheri Van Dijk
Psychiatrist (Therapist)

Here are some guidelines to help you determine what your sleep number is:

Start keeping a journal in which you record the number of hours you slept, and what you were like the next day. Did you notice you felt relatively good? Were you rested, or did you still feel tired? Did you notice an increase in your irritability? How was your concentration? Keep track of this for about two weeks, at which time you should be able to see any patterns. For example, you might notice that when you get eight hours of sleep, you typically feel okay, but if you get more or less than that, your mood isn't as good and you're more irritable.

If you don't feel rested with the current amount of sleep you're getting, you'll want to try adjusting this amount to see if you can improve how you feel. Since the average sleep requirement is about eight hours, it will be helpful for you to work your way toward eight hours. This means that, if you're currently sleeping ten hours each night (and waking unrefreshed or feeling irritable), then you'll want to work on decreasing your sleep to eight hours. And, yes, this will likely mean you'll have to set an alarm! Reduce your sleep slowly—by about fifteen minutes every couple of days—and see how you feel at each sleep number (continue recording this in your journal). Similarly, if you're generally sleeping less than eight hours (and feeling fatigued or irritable during the day), you'll need to increase your sleep by going to bed earlier or getting up later, in the same way, by about fifteen minutes every couple of days.

When you get to a sleep number where you feel more rested and your mood is better, you'll have found your sleep number. Keep in mind that if you have problems finding it, there could be some health problems getting in the way, such as depression or sleep apnea, and you should consult your doctor.

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Getting a good night's sleep is one of the most important things you can do for your body. While getting 8 hours of solid sleep is the age-old fabled goal, our needs seem to be a little less than that. Getting 7.4 hours of sleep a night for men and 7 hours of sleep a night for women can make a profound difference on your brain and your heart and have a RealAge effect of making you up to three years younger.

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The right amount of sleep is the amount you need to feel energized to do the things you need to do the next day. There is no exact number. Be mindful of signs of sleep deprivation like not feeling rested in the morning, memory problems or irritability.

Trinity Health is a Catholic health care organization that acts in accordance with the Catholic tradition and does not condone or support all practices covered in this site. In case of emergency call 911. This site is educational and not a substitute for professional medical advice, always seek the advice of a qualified healthcare provider.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.