Your sleep needs vary during your lifetime. How many sleep cycles you need to feel rested can also vary.

Keeping track of your sleep schedule might not always be your top priority, but getting enough good sleep is critical to your health.

Knowing how much sleep you need to function at your best can help you determine what time to go to bed.

This article is Day 2 of Healthline’s 3 Week Better Sleep Challenge. Follow along to discover small, meaningful habits to help you sleep better, feel more rested, and wake ready to thrive each day.

How much sleep you need changes throughout your lifetime. Sleep guidelines offer research-backed recommendations for the ideal amount of sleep for optimal health.

The American Academy of Pediatrics and the Centers for Disease Control and Prevention (CDC) provide these general guidelines for different age groups:

Sleep guidelines by age

  • Birth to 3 months: 14 to 17 hours (including naps)
  • 4 to 11 months: 12 to 16 hours (including naps)
  • 1 to 2 years: 11 to 14 hours (including naps)
  • 3 to 5 years: 10 to 13 hours
  • 6 to 12 years: 9 to 12 hours
  • 13 to 18 years: 8 to 10 hours
  • 18 to 60 years: 7 or more hours
  • 61 to 64 years: 7 to 9 hours
  • 65 years and older: 7 to 8 hours

Sleep needs can still vary depending on the person. What’s key is how you feel when you get various amounts of sleep.

Here are a few questions to consider when evaluating your sleep needs:

  • Do I feel rested after 7 hours of sleep, or do I need at least 8 or 9?
  • Do I experience any daytime drowsiness?
  • Do I rely on caffeine to keep me going throughout the day?
  • Has my sleeping partner noticed me tossing and turning or having any sleep issues during the night?

Bedtimes are based on:

  • your wake-up time
  • completing five or six 90-minute sleep cycles
  • allowing 15 minutes to fall asleep

Too little sleep can affect your body’s systems and restorative functions.

The occasional night of poor sleep generally won’t seriously impact your health. But, experts have linked ongoing sleep deprivation to serious health consequences, including a higher risk of chronic diseases and early death.

Sleep deprivation can impact short-term and long-term physical, emotional, and cognitive health.

Here, we answer common questions about sleep needs.

Do your sleep needs change with age?

Your need for sleep changes with age and typically stabilizes around age 20.

As you get older, you generally need less sleep. Environmental, behavioral, and medical factors can influence how much sleep you need, and those may change throughout your life.

Why am I still tired after sleeping for 8 hours?

There are a few possible reasons you might wake up tired, even after sleeping for 8 hours. A good place to start exploring these reasons? Consider your sleep habits and sleep hygiene practices.

If you wake up tired after sleeping for 8 hours, you may need to adjust your sleep hygiene practices or treat an underlying condition. Things that could detract from quality sleep include:

  • your sleep environment
  • movement or noise from a bed partner or pet
  • sleep disorders like insomnia or sleep apnea
  • chronic pain
  • an underlying medical or mental health condition

Is it healthy to nap during the day?

Taking naps longer than 30 minutes during the day may negatively affect sleep quality at night.

In a 2023 study, longer nappers who napped for longer than 30 minutes during the day had an increased risk for cardiovascular disease than people who napped for less than 30 minutes.

If you aim for 7 to 9 hours of sleep each night, a sleep calculator like the one above can help you figure out what time to go to bed based on your wake-up time.

Ideally, waking up at the end of your sleep cycle, when you’re most likely to feel rested, would be best.

Quality sleep supports good health, so if you’re having trouble falling or staying asleep, consider contacting a healthcare professional. They can help you explore the underlying causes of sleep difficulties and offer guidance.