Waking up at the wrong time can ruin your day. The When To Sleep Calculator enables you to wake between sleep cycles so can you can get the best sleep with the time you have available.



What time should I wake up?

Falling asleep at {{ clock_time_w_delay | date:'shortTime' }}, the best times to wake up:

(current delay of: {{ delay_length }} mins)

When to Wake UpSleep TimeSleep Cycles
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What time should I go to bed?

To wake up at {{ clock_time | date:'shortTime' }}, the best times to fall asleep:

(current delay of: {{ delay_length }} mins)

Time to Get In BedSleep TimeSleep Cycles
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How long does it take you to fall asleep?

Get more accurate results by setting the delay!

Keep in mind that this sleep calculator is based off of the average sleep cycle length of 90 minutes and based on a precise time that you are going to bed then falling asleep.

It takes an average of 15 minutes to fall asleep after getting in bed, so the default delay is 15 minutes. Adjust the delay time, in increments of 5 minutes from 0 to 30 minutes, to suit your personal sleep routine needs.


How to Use This Sleep and Bed Time Calculator

Get the Best Sleep with the Time You Have!


Before hitting the hay, consult the webapp. It works on phones, tablets and desktops.

The clock is used to generate two different types of time tables, one if you want to know when to set your alarm and one for when to head to bed.

Adjust the clock at the top to reflect your desired time for either falling asleep or waking up. The initial setting is the time right now.

Next, adjust the length of the delay based on how long it takes you to fall asleep after getting in bed. By default, it is set at the average which is 15 minutes.

The customized tables adjust automatically to your input at the clock and the delay.



Frequently Asked Questions (F.A.Q) about Sleep

Quick Answers to Common Questions About Sleep


Why use the When to Sleep Calculator?


The calculator makes it simple to figure out what times you should be sleeping. It provides the perfect bedtime or wake up time based on your schedule It also provides the length of sleep time in addition to the number of sleep cycles that are achievable.

Sleeping at the proper times can reduce or eliminate morning grogginess, also known as sleep inertia. Sleep inertia is what ruins most people's mornings, robbing them of productivity, lost time due to numerous alarm resets, interpersonal problems, memory difficulty and poor performance in general.

Avoid the snooze button and take back your mornings.

To wake up feeling refreshed you need to wake in between sleep cycles, not during one. While we can't guarantee you will wake between cycles, we can get close.

A full night's rest is typically 5 cycles for the average adult and more for children depending on age.

Keep in mind that it takes 15 minutes on average to fall asleep when scheduling your sleep.

The when to sleep calculator features an adjustable delay feature that moves in 5 minute increments, with the default set at 15 minutes. Adjust this delay based on your personal experiences.

How Long Should I Sleep?


Similar questions are:

  • How much sleep should you get?
  • How many hours of sleep should you get?
  • How much sleep do you need?

Everyone is different, but 7+ hours is generally the recommended amount of sleep for healthy adults. Seven and a half hours of sleep would be five complete sleep cycles.

Teens and children need more sleep than adults in order to not be sleep deprived, sometimes several more cycles than their parents. Naps are a good idea for to help younger children get the appropriate amount of sleep for their age group.

Consult the table below and get a better idea of what is a good guideline for the amount of sleep you should get for your age, or the age of your family members.

Amount of Sleep Required by Age
AgeAmount of Sleep
Newborns (0-3 months)14 - 17 hours
Infants (4-12 months)12 - 16 hours
Toddler (1-2 yrs)11 - 14 hours
Pre-School (3-5 yrs)10 - 13 hours
Elementary Age (6-12 yrs)9 - 12 hours
Teens (13-18 yrs)8 - 10 hours
Adults (18-64 yrs)7 - 9 hours
Older Adults (65+ yrs)7 - 8 hours

source: CDC recommendations

One hour, plus or minus, on the recommended time is still in the normal range.

If you wake up naturally, shortly before your alarm clock, just go ahead and get up to avoid grogginess. Don't try to get a few more minutes, it isn't going to help and will probably make you feel more tired.

What are Sleep Cycles?


A sleep cycle consists of four stages of NREM (non-rapid eye movement) sleep followed by a period of REM (rapid eye movement) sleep.

NREM is a period of time where your body is more quiet, with less dreams, slower heart rate, lower blood pressure and a lack of eye movement.

NREM Stages:

  • Stage one is the lightest stage of sleep and generally you may even feel like you are still conscious and experience sudden muscle twitches.
  • Most of the night is spent in stage two, which would be solidly asleep. The body temperature lowers, muscles relax and heart rates slows.
  • Stages three and four are the deepest NREM cycles in which it is most difficult to wake from. Stages three and four are combined together and referred to as slow-wave, delta or deep sleep.

The REM portion of your sleep is a more active period of sleep. This portion of sleep is when you experience most dreams, higher blood pressure, a more rapid heart rate, shallower breathing and rapid eye movement. The body even paralyzes itself in order to prevent acting out during dreams.

During REM is also when the brain begins to place short term memories into to long term memory as well as flushing out toxins that have built up in your brain. Staying hydrated during the day will help your brain to repair itself at night so you feel alert, refreshed and renewed the next day.

At the beginning of the night, NREM stages are the bulk of the sleep cycle with REM being fairly brief. As the night goes on, the NREM portion gets shorter and REM gets longer.

Usually, in the morning you should wake up during or at the end of an REM stage, which is why you wake during a dream.

Avoid hitting snooze! You won't feel more rested, in fact you may even feel worse if you go back into a NREM stage and you probably won't finish your dream.

How Long is a Sleep Cycle?

You can use When to Sleep as a Sleep Cycle Calculator


One complete sleep cycle is right around 90 minutes on average.

A full night's sleep for most people consists of around 5 complete cycles (7.5 hours) for adults. Teenagers and children need more complete cycles depending on their age.

Alternatively, some people use an afternoon nap to supplement a shorter period of sleep at night of four cycles, which is around 6 hours.

If you want to calculate the number of sleep cycles you can get with your available sleep time, the number of complete sleep cycles are listed in the sleep time tables calculated by the app.

When should I go to Bed?

This app is also a Bedtime Calculator


Adjust the clock at the top of the bedtime calculator to reflect your desired alarm time.

Next, look at the "What time should I go to bed?" sleep time table for a list of bed times that would be appropriate for your personal sleep requirements.

What is Sleep Deprivation?


Sleep deprivation, is simply the compounding of health effects that result from not getting enough sleep for whatever cause - insomnia, sleep apnea, hectic work schedule or other reasons.

Being deprived of sleep can result in more than just a bad mood, impaired judgement or memory problems.

Sleep is when the body repairs itself, flushes toxins from the brain, heals from injury and grows in the case of children and teens. If the body doesn't receive the necessary amount of sleep to repair itself, it starts malfunctioning, hence the term sleep deprivation.

Not getting enough sleep over a period of days, weeks or even years can result in serious mind and body issues that can have devastating health impacts such as:

  • weakened immune system
  • harder time recovering from injury or illness
  • high blood pressure and increased risk of heart disease
  • greater risk of depression, irritability, anxiety, forgetfulness, reduced cognitive ability and lowered response time
  • increased risk of dementia
  • higher risk of obeasity and diabetes - sleep deprivation causes your body to crave, sweet, salty and starch based foods due to hormone imbalances (higher levels of hunger hormone ghrelin and lower levels of appetite control hormone leptin)

source: Johns Hopkins Medicine

Will taking a nap mess up my sleep schedule?

Are naps bad?


Taking a nap can actually be quite helpful and are a normal supplement to a shorter period of sleep received the previous night to "catch up".

In most cases, taking a nap won't effect your sleep schedule, but that depends on the time and duration of the nap.

Keep the nap under 90 minutes, early in the afternoon after lunch and you should be fine.

Avoid taking your nap in the late afternoon or evening as this may actually throw your normal sleep schedule off by several hours.

Taking a twenty to thirty minute cat nap or even a hour long power nap is normal in most part of the world. Even sleeping a full 90 minutes can be helpful if you are having issues with not getting enough sleep at night.

If you don't want to fall asleep, you can get some benefits by simply laying horizontal on your back with your eyes closed. This will allow you to lower your blood pressure, relieve stress on your body and relax your muscles for long enough to get some rest to feel more refreshed for the rest of the afternoon.