How much sleep do I need?

Find your optimal amount of slumber, and learn how to track your sleep in the WW app.
Published 5 May, 2020

Along with nutrition and physical activity, sleep is a cornerstone of good health.

As researchers continue to uncover new insights about this complex biological process, it’s clear that a lot of important stuff happens when we snooze. The brain creates pathways for learning and memories, for instance, and certain tissues regenerate.

By the same token, getting too little sleep is linked with a range of negative health effects. Given all that, wanting to achieve the optimal amount of good quality sleep makes sense. But how much sleep do you really need? 

The answer depends on a range of personal factors, sleep specialists say. Here’s how to figure out the best sleep plan for you.

Recommended sleep guidelines

Let’s start with the baseline range: most adults should aim for seven to nine hours of sleep a night to feel their best, says Douglas Kirsch, MD, FAAN, FAASM, medical director of sleep medicine at Atrium Health, a healthcare organization in Charlotte, North Carolina. Within that range, needs vary with age. The younger you are, the more sleep you generally need.

Sleep needs by age

Here’s a breakdown of recommended sleep durations across age brackets:

  • Birth to 3 months: 14–17 hours a day
  • 4–11 months: 12–15 hours a day
  • 1–2 years: 11–14 hours a day
  • 3–5 years: 10–13 hours a day
  • 6–13 years:  9–11 hours a day
  • 14–17 years:  8–10 hours a day
  • 18–64 years: 7–9 hours a day
  • 65 and older: 7–8 hours a day

What time should I go to bed and wake up?

As research on the importance of sleep continues to grow, a bevvy of apps, gadgets and sleep calculators have hit the scene, all promising to help you achieve sweet dreams. 

But high-tech toys and calculators might not crack the code on what you really need to feel well rested. Even among adults of the same age and sex, sleep needs vary according to environment, lifestyle and genetics, among other factors. No "perfect" number exists for any particular group of people, a 2018 review article in the journal Nature and Science of Sleep found.

So here’s what to do instead: aim for the sleep range recommended for your age, then ask yourself some key questions:

  • Do you wake up feeling refreshed?
  • Are you tired throughout the day?
  • Is tiredness keeping you from being as productive as you’d like to be?

Tracking your responses against your sleep schedule may reveal useful insights particular to you.

Understanding your sleep cycle

Sleep isn’t a uniform state. It cycles in four distinct stages, and all are important to a truly restful experience. Sleeping with minimal interruptions supports a healthy sleep cycle.

An adult getting seven to nine hours of sleep goes through four to five sleep complete cycles per night, Kirsch says. Each lasts 90 to 120 minutes and comprises two kinds of sleep: REM (rapid eye movement) sleep, and NREM (non-rapid eye movement) sleep. 

NREM sleep accounts for about 75% of all snooze time, according to the National Sleep Foundation, and happens in three stages, called N1, N2, and N3.

  • N1: When you’re just falling asleep or sleeping lightly.
  • N2: The onset of sleep. Breathing and heart rate are steady. Body temperature drops.
  • N3: Also known as slow-wave sleep, this stage is the most restorative, Kirsch says. Muscles relax, blood pressure drops, breathing slows, and growth and repair of tissue begins.

Next in the sleep cycle is REM sleep, which accounts for about 25% of nightly shut-eye. REM phases occur about every 90 minutes, give or take, with installments lengthening slightly as the night goes on. During REM, the body becomes relaxed and immobile, dreams occur, and as you might expect from the name of this sleep stage, eyes dart back and forth beneath the lids. The stress hormone cortisol dips. (It’ll rise again as morning approaches - a built-in alertness booster).

Track your sleep in the WW app

Because sleep is so important for your overall wellbeing (and can even support your weight loss goals) we've added a sleep tracker to the WW app. Here's a quick summary: