Sleep Calculator

Find out how much sleep you need to get your ideal rest!

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For a 8:30 AM wake up time, you should sleep at…

  • 9:30 PM 9 hrs of sleep, 6 sleep cycles Ideal Bedtime
  • 11:00 PM 7.5 hrs of sleep, 5 sleep cycles Later Bedtime
  • 1:00 PM 6 hrs of sleep, 4 sleep cycles Last Bedtime

Most of us grew up with a bedtime that our parents enforced. After all, we had to get enough sleep to do well in school the next day. Some of us even woke up early without an alarm clock, or our parents shaking us awake.

Once we reach adulthood, we have more freedom to decide when we go to sleep. Many of us take this freedom too far and lack a proper sleep schedule. We may choose to stay up to get more work done, spend more time with friends, or watch a show.

You might think that you can make up for a late night with an early bedtime the next night. But if your sleep schedule remains in flux, you may find it difficult to fall asleep whenever you want to.

How We Sleep

Before we explain how to determine how much sleep you need, let’s discuss how your sleep cycles work.

We move through four stages of sleep during the night. There are three stages of non-REM sleep and one stage of REM (rapid eye movement) sleep. Once you move through all four stages (which takes about 90 minutes), you have finished a sleep cycle.

Most people experience four to five sleep cycles a night. You spend more time in the non-REM stages of deep sleep during the first few cycles, with latter cycles focusing more on REM and light non-REM sleep.

To feel most refreshed, you should set your alarm clock to go off during the first stage of sleep. This stage is when you’re most easily awakened. Many smart mattresses include an alarm that will wake you during the lighter stage of sleep, but for those without this technology, a sleep calculator can help you set your best bedtime and wake up time.

Getting a Full Night’s Rest

The best way to get a good night’s sleep is with an established bedtime. Set a time to fall asleep and wake up, and stick to the schedule even on your days off.

To clarify, your ideal bedtime is the time you want to be asleep by, not when you first lie down in bed. Most of us can’t switch off as soon as our heads hit the pillow, so you should budget in the time it takes to fall asleep. The average time it takes to fall asleep is 15 minutes, though you should get into bed earlier if you tend to take longer.

How do you figure out when you want to fall asleep? Start backward with your ideal wake up time. Perhaps you want to get up at 7 a.m. The average adult needs 7 to 9 hours of sleep, so your best time to go to bed is between 10 p.m. to midnight.

That’s the simple version. To narrow it down further, you need to consider how your age, genetics, and activity levels affect how much sleep you need.

Age and Sleep

How much sleep we need changes as we get older. Newborn babies need to spend about 16 hours of the day asleep while the elderly may only need 7.

The recommended daily amount of sleep for each age group is:

  • Newborns (0-3 months): 14-17 hours a day
  • Infants (4-11 months): 12-15 a day
  • Toddlers (1-2 years): 11-14 hours a day
  • Preschoolers (3-5): 10-13 hours a day
  • School age children (6-13): 9-11 hours a day
  • Teenagers (14-17): 8-10 hours a day
  • Adults (18-64): 7-9 hours a day
  • Older adults (65+): 7-8 hours a day


All of us have an internal clock that governs our sleep-wake cycle, known as a circadian rhythm. Our genetic makeup is the main influence on our circadian rhythms. Some of us are predisposed to being morning larks, and others are night owls.

Of course, genetics is not the sole factor that affects your biological clock. Light exposure and climate can affect your circadian rhythms as well. And those of us who have suffered jetlag know how travel can upset our internal clock.

Activity Levels

What tasks fill your waking life? Do you spend the day on your feet and physically active, or do you have an office job that lets you sit down? What you do during the day affects how much energy you need to restore through sleep.

For example, students and pro athletes may need to sleep for 10 hours to reach their peak performance. They expend so much energy that an average night of sleep isn’t enough.

Seven hours of sleep may be enough if you have a laidback lifestyle. But if you’re barely able to stay on your feet and keep your eyes open at the end of the day, you might need to budget for 8 or even 9 hours of sleep.

How to Quickly Fall Asleep

Deciding what time you should go to sleep is the easy part. It’s the follow-through that many people find tricky. Adapting to your new schedule should be easier with our sleep tips.

Create a Bedtime Routine

If you go straight from the day’s work to bed, your brain and body may find it hard to relax. An established routine tells your body it’s time to sleep. Many people like to unwind with stretches and breathing exercises, a warm bath, or a good book.

Avoid using your bed for things other than sleep. You want to think of your bed as a place to be restful, not active. Don’t work on your laptop or read the latest news updates on your phone while lying down. You might even want to avoid reading a book in bed if you can, though many people do so and maintain a healthy sleep schedule.

Avoid Stimulants

Caffeine takes hours to work its way through your system, and it still affects your body even after you can no longer feel it. Try limiting your coffee intake to the morning, and maintain a careful eye on what you consume after lunch. Chocolate, tea, and many sodas contain caffeine. Even decaf coffee has trace amounts of caffeine.

It’s also a smart idea to restrict how much you eat before bed. Your body digesting a large meal may keep you awake or cause you to wake up with acid reflux. Scheduling your last meal around four hours before bed should make it easier to relax and improve sleep quality.

In today’s electronic age, it might be hard to turn off all your gadgets. However, switching them off at least an hour before bed is one of the most effective steps toward a good night’s sleep.

The blue light of an electronic screen mimics daylight, which tricks your brain into halting its production of melatonin. Our bodies create melatonin at night to help us fall asleep.

If you’re the type who likes to read before bed, try to avoid a page-turning thriller that will tempt you to skip bedtime. Instead, relax with a favorite novel or a short story collection. It will be easier to put down as you grow tired.

Make Your Bedroom Rest-Inducing

If you have trouble falling asleep, set up your bedroom for quiet and relaxation. Make sure you have the best mattresses, pillows, and sheets for your sleep needs. That may mean a thicker pillow if you’re a side sleeper or breathable cotton sheets if you tend to sleep hot.

Your bedroom temperature should be kept cool, ideally between 60 to 70 degrees Fahrenheit. Minimize loud noises and bright lights. A small night light or the sound of a fan is okay if it helps you relax. You should feel calm and worry-free as you lie down.

If you’re an anxious clock watcher, turn your alarm clock away so it’s not displaying the time. Otherwise, you may find yourself fretting about how you should already be asleep, ironically stressing yourself out so much that it becomes more challenging to fall asleep.

Waking Up Refreshed

Getting enough sleep helps you make the most of your day. Your thinking is clearer, your reactions are faster, and your mood is better after a full night’s rest.

Going to bed at the same time will make it easier to achieve your recommended amount of sleep. Your new sleep schedule may take some getting used to, and for the first few mornings, you might feel groggy as your body adjusts. Once your body clock is rewired, you should find your days are more productive and enjoyable.