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 kids grow up adhering to a relatively fixed bedtime and wake up early with no problems. But as an adult, the time you plan to go to sleep feels negotiable. Whatever hour you had in mind can quickly change depending on your workload, evening plans, or even just your mood.

Ever-changing bedtimes can cost you much-needed sleep. And a few too many late nights can leave you exhausted, sluggish, and promising to get to sleep earlier that night.

Deciding to fix your sleep schedule is the first step to making sure you get enough rest. The next step is determining what time you should actually go to sleep.

Your ideal sleep time — the hour that will have you waking up well-rested and ready for the day — depends on your age, genetics, activity levels, and sleep cycle. Learn the role each of these factors plays in your ideal bedtime and figure out how many hours of sleep you need below.

How Much Sleep Do You Need?

how much sleep do you need?

The best way to figure out what time you should sleep is to work backward. Take the time you plan to wake up (say, 6 a.m.) and subtract the recommended 7 to 9 hours of sleep (which is around 9 to 11 p.m. the night before). This is your bedtime ballpark.

To hone it down further, there are other individual factors to consider — age, genetics, daily activities, and the like.

Your Age

The amount of sleep you need changes with age. While infants require nearly 20 hours of sleep a day, seniors can do with much less. Below, we break down the recommended sleep requirements by age:

  • 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


Much of the way you sleep is embedded in your genes. All humans have an internal clock, known as their circadian rhythm, in place to regulate their sleep-wake cycle. The circadian biological clock is something you’re born with and is primarily determined by your genetic makeup.

Studies show that genetics — specifically the PER1 and CRY1 genes and other parts of our hypothalamus — play a big part in your sleep habits, sleep needs, and preferred bedtime. Even the slightest shift can mean the difference between someone being a morning lark or a night owl.

Circadian rhythms are also affected by external experiences, like light exposure, traveling through time zones, climate, etc. But for the most part, being aware of your natural sleep-wake cycle can help you decide whether you’re inclined to sleep a little bit earlier or later.

Daily Activities

You may have to be up at a certain time every day, but what do you do during the hours you’re awake? Are you on your feet the entire day, or sitting down most of the time? Do you engage in physical activities or lead a more sedentary life?

These all add up to the total energy you expend in a day, and therefore, how much more or less sleep you need to compensate. A good rule of thumb is if you are fairly tired, 7 hours of sleep may be enough. But if you feel physically spent at the end of the day, try to get some more shuteye.

The Best Time for You to Go to Sleep

You know what time you have to get up and have an idea of how many hours of sleep you need. The final step is to account for your sleep cycles.

Rather than one long slumber, we go through four stages of sleep — three stages of non-REM (rapid eye movement) and one stage of REM sleep. All these stages make up a complete sleep cycle and last about 90 minutes total. A full night’s rest of 7 to 9 hours of sleep will typically have four or five sleep cycles.

To wake up feeling refreshed, your alarm clock should go off when you’re in a light sleep stage, early in the sleep cycle.

A simplified approach would be to base your sleep on 90-minute increments, say 7.5 hours, and set your alarm accordingly. However, sleep cycles change as you sleep. The first few cycles have longer periods of non-REM deep sleep, while later cycles are mostly spent in light non-REM and REM sleep.

Thankfully, there are many online sleep calculators and tools to help you find the best time to go to sleep, get enough rest, and wake up at the ideal stage of sleep.

How to Fall Asleep Quickly

how to fall asleep quickly

Setting an optimal time to sleep is easy enough. But sticking to it every single day comes with its challenges. To help you adjust to your new sleep schedule, try some of these better sleep tips below.

Create a Relaxing Sleep Environment

Going to sleep on time will be much easier if the place you sleep is quiet and relaxing. Start by investing in the best mattress, pillows, and sheets for your particular sleep needs. Keep the surroundings at a cool temperature, and devoid of any loud noises and bright lights. You can opt to turn on a small night light or fan, or place a small diffuser in the corner — as long as you feel calm and ready for bed.

Have a Nighttime Routine

Sometimes, your brain and body need to be coaxed into going to sleep. Having a bedtime routine can help signal to your senses that it’s time to start slowing down. Some good ways to get ready for bed include taking a soothing bath, reading a light book, or practicing mindful breathing exercises.

On that note, try to avoid doing a lot of activities in bed, such as answering work emails or messages on your phone. It’s best if you don’t use or associate your bed space with being busy or active.

Note that your bedtime is when you should actually be asleep, not start going to bed. Unless you’re one of the lucky ones who can fall asleep as soon as your head hits the pillow, add a little buffer of about 15 minutes, which is the average time it takes someone to fall asleep. (If yours is longer, feel free to get into bed earlier.)

Remove Any Stressors

If you are sensitive to caffeine, try limiting your coffee to the morning or switching to decaf after lunch. You can also move your dinner time an hour or so earlier. This will give you enough time to digest, especially after a big meal, and allow your body to relax and sleep better.

Although difficult, you may find it helpful to turn off your gadgets at least an hour before bed. Electronic screens emit a blue light that disrupts our body’s production of melatonin, a hormone that helps your body to prepare for sleep. In addition, face any clocks or alarms away from you. If you have trouble sleeping, continuously checking the time will likely stress you out more and keep you awake.

Early to Bed, Early to Rise

The first step to making the most of your day is having a good night’s sleep. You can achieve this by setting a nighttime routine, going to bed at a regular time, and getting your recommended amount of sleep. While a new schedule may take some time and effort to get used to at first, getting the rest you need at the end of the day makes a world of difference.