Sleep Calculator

Choose the Time You Want to Wake Up

15 minutes has been added to adjust for the average time it takes to fall asleep.

You Should Go to Bed at:

This gives you 9 hours of sleep and 6 sleep cycles.

This gives you 7.5 hours of sleep and 5 sleep cycles.

This gives you 6 hours of sleep and 4 sleep cycles.

The National Sleep Foundation recommends adults should be getting 7-9 hours of sleep per night. But what if you’re hitting that goal and are still feeling tired and groggy? According to the National Sleep Foundation’s Sleep Health Index you’re not alone. Americans spend an average of 7 hours and 36 minutes sleeping each night. Despite getting enough sleep, 35% of Americans describe their sleep quality as “poor” or “only fair.” Maybe striving for a certain amount of hours each night isn’t the answer to feeling rested. In fact, new research suggests understanding the sleep cycle may be the key to a better night’s sleep.

By understanding the sleep cycle we’re able to figure out the ideal time to fall asleep so that we wake up feeling refreshed. A full sleep cycle is approximately 90 minutes divided into phases ranging from light sleep to deep REM (rapid eye movement) sleep. The beginning sleep stages are light sleep. Being woken up in these stages has been proven to make people more energetic and alert. However, if woken up during the final sleep stage, REM (rapid eye movement), people tend to feel groggy and disoriented. Therefore, the key to waking up refreshed is waking up during light sleep.

The graph above illustrates the stages of sleep in relation to how many hours you’ve been asleep.

Stage 1:
You may notice we spend very little time in Stage 1 sleep. In fact, less than 5% of our total sleep is in this stage. Here, you will notice muscle relaxation, lower body temperature and a slower heart rate.

Stage 2:
We spend about 50% of our sleep time in stage 2. This stage is still considered light sleep, however your body is preparing for deeper sleep.

Stage 3, 4 and REM:
In the final stages of the sleep cycle your body is in deep sleep. This is when your immune system works to repair the day’s damage. Your body also repairs and regrows tissue and strengthens bones and muscles. REM occurs about 90 minutes after you fall asleep and accounts for about 20% of your time asleep. As the name implies, REM includes frequent and rapid movement of the eyes. This is when your heart rate and breathing accelerate. Your most intense dreams occur during REM sleep since this is when your brain is the most active.

You may have heard that interrupted sleep is as harmful as no sleep at all and that is certainly the case if you wake up during deep sleep. If you are awakened during REM sleep you are most likely to remember your dreams, however waking up during deep sleep is almost certain to make you feel groggy, like you didn’t sleep at all.

Now that we understand each stage, when they take place and for long, we can figure out when we should go to sleep based on what time we need to be awake.

With the HIBR sleep calculator, we incorporated all the science and did the math for you. The calculator allows you to figure out the exact time you should go to bed in order to get the best night’s sleep.

To use the calculator, simply enter the time you need to wake up. The sleep calculator will then provide three optimal times for you to fall asleep. It also takes into account that it takes the average person approximately 15 minutes to fall asleep.


What To See The Code?

We open sourced the code, check it out here.