[Android] Not getting enough sleep? Calculate your sleep time with 90night

90night for AndroidWorried that you might not be getting the needed amount of sleep that your body needs? Well, that could be a problem since getting enough sleep is just as important as the nutrients that you get from the food that you eat. It’s just that there are many factors that could greatly affect a person’s sleep. One of this is a phenomenon that sleep researchers usually refer to as “sleep inertia” – which is often associated to a state in which a person wakes up while still in the middle of his/her slow-wave (SWS) sleep cycle. Speaking of which, this is the main reason why sleep cycle apps like 90night exists.

What Is It and What Does It Do

Main Functionality

90night, also known as 90night: SleepyTime Calculator, is a simple sleep cycle calculator that you can use to calculate the total amount of time that you need to sleep. The main purpose of this app is to help you determine or calculate the ideal time for you sleep or wake up. By doing so, you can refrain yourself from waking up in the middle of your critical sleep cycles and thereby preventing you from feeling “groggy”. Moreover, 90night is easy to use. Just enter the time that you are going to bed or the time that you are going to wake up and then it will show you the best possible time/s for you to wake up or go to sleep. Like, for example if you happen to go to bed at 2:03AM then you need to wake up at 11:03AM to get your required amount of sleep. What’s also great about this app is that it can automatically set the alarm for your sleep or wake up time.


  • Easy to use
  • Automatically calculates the ideal time for you to wake up or go to sleep
  • Automatically sets the alarm on your device so that you’ll know when to sleep or wake up
  • Supports both 24-hour and 12-hour time format
  • The app’s UI features both dark theme and light theme
  • You can add snooze alarms
  • Configurable user settings


  • None that I can think of – except for the fact that the effectiveness of this app may vary per user


90night SleepyTime CalculatorFunctionality wise, 90night definitely does a good job. It works accordingly and it would be very less likely for you to experience some bugs and glitches while using this app. In addition, this app mainly serves one purpose and that is to help you determine the time that you need to sleep as well as the time that you need to wake up. Why so? As I’ve already said above, waking up in the wrong sleep cycle stage will greatly affect your waking state. This means that you will not only feel groggy, your mental alertness will also decrease in such a way that you can’t even get your body to work at its best state.

In order to properly calculate your sleep time with 90night, what you need to do is to set it first. You basically have three options and these are as follows:

  • Bed time entered/Need wake time – you get to enter the time when you go to bed and the result will show the time that you need to wake up
  • Wake time entered/Need bed time – you get to enter the time that you woke up and the result will show the time that you need to sleep or take a nap
  • Go to bed now – similar to bed time entered/need wake time but instead of manually setting the time, the app will automatically indicate the time that you’re actually going to bed

What I also like about this app is that it can set your alarm clock based on your chosen sleep time or wake time. It also has a snooze feature which proves to be very handy for people who wish to extend their peaceful sleep time. In addition, this app also supports both 12-hour and 24-hour time format.

All in all, I can say that this app can be very useful especially for people who wish to improve their quality of sleep. Some may say that this app isn’t really effective but you will never know if it’s really good or not unless you try it.

Conclusion and Download Link

The effectiveness of 90night: SleepyTime Calculator may vary amongst its users but it definitely does a good job in what it’s intended to do. It also gives accurate results for the time that you need to sleep or wake up. Therefore, my best advice for you is to use this app at your own discretion.

Price: Free, Pro – $0.99

Version reviewed: 3.0

Requires: Android 2.3 and up

Download size: 466KB

90night: SleepyTime Calculator on Play Store

Related Posts