When your phone puts unused apps to sleep, it means well — the intent is to extend your battery life by reducing the number of apps which are needlessly using system resources and wasting power. On some phones, like those made by Samsung, when the OS notices that a particular app hasn’t been run for a while, it’ll hibernate that app automatically, after the sleep delay found in Settings. While a sleeping app can be “re-hydrated” quickly when you try to open it, the app can’t exchange data in the background while it’s asleep. That means incoming notifications could be very delayed (or not arrive at all), leading you to potentially miss what could be an important piece of information from a "slept" app. Given there’s little evidence that putting most background apps to sleep provides significantly better battery life, it's understandable why you might want an "off" switch for this behavior. Thankfully, you can take manual control of sleeping apps. Here's how to do it.

The below steps should work for most Android phones with Oreo (Android 8.0) or above. Some smartphone manufacturers, however, completely replace Android's battery optimization for their own implementations. In those cases, you'll need to consult a manufacturer-specific tutorial.

  1. Start the Settings app and find Battery Optimization in the Apps section.
  2. At the top of the screen, tap "Not Optimized" and then tap "All apps." You should now see a list of all the apps on your phone. Each app is marked "Allowed" or "Not allowed." Allowed means that your phone is allowed to put the app to sleep when it's in the background.
  3.  Find an app that you don't want to go to sleep, and tap it. In the pop-up, choose "Don't allow" and confirm your choice by tapping "OK."

Setting an app to "not allow" sleep in background

That's it — though you will need to repeat that process for each app which you want to keep awake in the background. These settings should survive a reboot of your phone and will allow these apps to run normally. If you ever want to turn the battery optimization back on, just go back to that same menu, and find the apps you've exempted in the "not optimized" list.

Make sure your apps don't sleep in the background on Samsung phones

If you have a Samsung device running One UI, Samsung provides another way to control sleeping background apps. It's somewhat easier to use, and can supersede (but also kind of duplicate) the OS-level battery optimization setting. If you do have a Samsung phone, make sure you've set this up as well as the above battery optimization setting to make sure an app doesn't go to sleep. If you tell the Android OS not to optimize the battery life of an app, but not the Samsung settings, your phone may still put it to sleep.

  1. You’re going to have to go deep to find these controls. Start the Settings app and tap “Device care.” Then tap “Battery.” On the Battery page, tap "App power management."
  2. Samsung maintains a list of apps that are never permitted to go to sleep. To see the list, tap “Apps that won't be put to sleep.” You can add additional apps to this list by tapping "Add apps."

Samsung's App power management settings

  1. To disable background apps from going to sleep at all, turn off "Put unused apps to sleep."