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The science of sleep: How many hours do you need?

Clinically reviewed and updated by Jenilee Matz, MPH May 25, 2023 • 5 min

Conventional wisdom says eight hours is key when it comes to sleep. But studies show eight might not be the magic number for everyone. So how do you know if you're getting the sleep you need?

Why is sleep so important?

Many of us agree that we don't get enough of it. But that dragging, heavy-lidded feeling isn't the only bad result of sleep deprivation. Over time, poor sleep can lead to serious health risks. Short sleep duration is linked to obesity, type 2 diabetes, heart disease and depression. Lack of sleep also increases the risk of motor vehicle accidents. (Drivers, take note: The Centers for Disease Control and Prevention, or CDC, cites tiredness as a factor in up to 6,000 fatalities each year.)

What can sleep do for me?

Not only do healthy sleeping habits help lower the risk for sleep-related accidents and certain health conditions, but good sleep can also help you:

  • Lower stress levels and improve mood
  • Maintain a healthy weight
  • Avoid getting sick
  • Think more clearly and perform better on the job
  • Make safe choices and reduce the chance of injuries

How many hours are enough?

Sleep needs are individual and vary based on age. Adults generally find seven to nine hours per night adequate, while some active school-age children can require as many as 11 or 12 hours. The quality of sleep, or how well you sleep, also affects the quantity you need. People with frequently interrupted sleep, such as those with a sleep disorder like sleep apnea, won't feel as rested as people who sleep soundly through the night. Research has also linked sleeping too much to a higher risk of diabetes, heart disease, headaches, depression and fatigue. However, more research is needed to understand this possible association.

So the question is, how do you find the right number of hours of sleep per night for you?

Get on track for better sleep

There are several ways to create healthy sleeping habits. Consider keeping a sleep log and noting your mood, energy level and health after different amounts of sleep. If you're feeling productive and happy on eight hours of sleep, you've likely found your sweet spot. On the other hand, if you find it difficult to wake up or you rely on caffeine throughout the day to stay awake, there's a good chance you need more sleep.

Technology can also help you track your sleep patterns. For example, fitness devices can help you set reminders for bedtime, waking up, and offer a peek into how much sleep you get each night.

Tips for a good night's sleep

The key to a good night's rest? Consistency and a plan. Set a sleep and wake schedule and a regular bedtime routine, and stick to it, even on weekends. In addition, the following healthy sleep tips may help:

  • Practice a bedtime ritual that's relaxing, such as reading a book
  • Make sure your bedroom is a comfortable temperature and minimize sounds and lights
  • Exercise regularly, but avoid intense workouts close to bedtime, because it can make falling asleep more difficult
  • Get exposure to natural light for at least 30 minutes earlier in the day
  • Reduce your screen time at least one to two hours before bed
  • Invest in a comfortable pillow and mattress
  • Avoid large meals, alcohol and caffeine in the hours before bedtime

Worried about your sleep?

Sometimes health problems can keep you from getting adequate sleep. See your healthcare provider if you have any of the following symptoms:

  • Sleepiness during the day that makes it difficult to do everyday tasks
  • Snoring
  • Itchiness or crawling sensations in your arms or legs when you try to sleep which resolves by moving around 
  • Gasping or trouble breathing during sleep
  • Insomnia (trouble falling or staying asleep) or another issue that keeps you from sleeping well
  • Tiredness after a good night's sleep

Your healthcare provider can help figure out the cause of your sleep troubles and get you on your way to a better night's sleep.

Clinically reviewed and updated May 2023.

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