Samsung – alarms and notifications
Source: Don’t kill my app
Explanation
UPDATE: We record significantly increased number of app killing on Samsung’s Android Pie flavor. The hints show adaptive battery being much more eager than in stock Android. After 3 days any unused app will not be able to start from background (e.g. alarms will not work anymore). We strongly suggest to turn off battery optimisation and Put apps to sleep options per instructions below.
IMPORTANT: Latest feedback suggests that even when those options get disabled Samsung may re-enable than later after a firmware update! Yes, Samsung – a dominant vendor in the Android market – is now using one of the nastiest battery saving techniques in the industry. They kill background processes and render alarm clocks and other apps which rely on background processing useless. See below for workarounds.
Solution Galaxy S9 / S10
Battery optimization is turned on by default. At some unclear moments (maybe on app update, OS update?), the settings also do revert back to the defaults, forcing you to turn them off again and again. Below are walkthrough screenshots for Galaxy S10.
Battery optimisation
Overall it is a good idea to make Circadian not battery optimized to ensure it gets the freedom it needs to perform in the background.
For that:
- Go to Phone settings > Apps > Circadian > Battery > Optimise battery usage
- Change view to All apps
- Search for Circadian
- Choose Not optimized

Sleeping apps
Sleeping apps menu is the sniper’s nest for Samsung’s app killing policies. Make sure to follow the instructions very carefully to prevent the apps from being killed.
Checklist:
- Disable Put unused apps to sleep
- Disable Auto-disable unused apps
- Remove Circadian from the list of sleeping apps
- Disable background restrictions for your app
1. Start Device care
from phone settings

2. Tap Battery

3. Tap the 3-dot
menu > Settings

4. Disable all toggles
(except Notifications)

5. Tap Sleeping apps

6. Wake up all the apps using the trashcan icon

WARNING: Make sure that Put unused apps to sleep and Auto-disable unused apps is disabled. Otherwise, Samsung will put your apps back to sleep after a few days (3 by default) even if you have woken them up manually
Galaxy S8 (j6ltedx) and later
With the introduction of their flagship Galaxy S8 (and with some earlier experiments), Samsung has introduced a flawed attempt at prolonging battery life called App power monitor.
For your apps to work correctly, please whitelist them in App power monitor.
How to do it:
Open the Settings > Device maintenance > Battery and at the bottom you’ll see a list of your most frequently used apps. You can manage apps individually or in a group by selecting them then tapping the big Save power button. Apps that are sleeping will appear in the Sleeping apps list at the bottom (tap it to expand the list). Scrolling further — all the way to the very bottom — and you’ll find Unmonitored apps. These are apps that you specifically want to exclude (white list) from App power monitor evil reach.
When inside the Unmonitored apps menu, you can tap the 3-dot menu to add or delete apps from the list. Rather than bothering with any of that, you can just turn off the App power monitor feature completely as it has little-to-no impact on battery life and only serves to handicap the normal functioning of your Galaxy phone.
It’s excessive and in some cases downright misleading, using scare tactics to keep you reliant on Samsung’s software when other Android devices get by just fine without it.
On other Samsung phones, the path may look like this:
Phone settings > Applications > select three dot menu (top right corner) > Special Access > Optimize Battery usage > Find Circadian on the list and make sure that it is not selected.
NOTE: If you enable Edge Lighting for Circadian, then the app might not be able to wake up your screen. To allow Circadian to wake up your screen, please remove it from the Edge Lighting applications list.