Why Your Android Alarm Doesn't Go Off (and How to Fix It)

By the Somnia team · October 30, 2026 · 7 min read

Waking up late because your alarm "just didn't go off" is maddening, and it is more common on Android than it should be. Android is built to save battery, and alarm apps have to work inside rules that change with every version and every phone maker. The good news is that the causes are known, and most of them take a minute to fix.

Why does an Android alarm fail to ring?

In practice, a missed alarm on Android almost always comes down to one of these:

• Doze and battery saving delayed or blocked the app that owns the alarm.
• The exact alarm permission ("Alarms & reminders") is off, so the alarm cannot be scheduled for an exact time.
• Notifications or full-screen alerts are off, so the alarm fires but you never see or hear it properly.
• A phone maker's battery manager put the app to sleep.
• Do Not Disturb, silent mode or a low alarm volume muted it.
• A restart cleared the alarm and the app did not set it again.

How do Doze and battery optimization affect alarms?

When your phone sits still with the screen off, Android enters Doze, a deep power-saving state. Android's developer documentation says Doze "defers standard AlarmManager alarms, including setExact() and setWindow(), to the next maintenance window". In plain words, an ordinary alarm can be pushed back until the system next wakes up.

Android does give real alarm clocks a way through. Alarms set with the alarm-clock method "continue to fire normally", and the system leaves Doze shortly before they ring. Not every app uses it, though, and battery settings can still get in the way. If you mark an app as "Restricted" on battery, Android puts it in its most limited group, where the documentation says an app "can invoke one alarm per day". For an alarm app, the safest battery setting is Unrestricted (the name varies by phone).

What is the "Alarms & reminders" permission?

Since Android 12, apps need a special permission to schedule exact alarms. You can find it in Settings under "Alarms & reminders" (search for it if you can't see it). From Android 14, this permission is no longer granted automatically to newly installed apps that target recent Android versions. That means a freshly installed alarm app may need you to turn it on.

Apps whose main job is being an alarm clock can instead use a separate permission that is granted automatically and that users cannot revoke, but Google limits it to alarm and calendar apps. Either way, if your alarm app says exact alarms are off, turn them on.

Why does the alarm ring silently or only show a small notification?

Two more permissions matter. On Android 13 and newer, notifications are off by default for newly installed apps until you allow them. And on Android 14, the permission to show a full-screen alert over the lock screen is reserved for calling and alarm apps, and you can switch it off in settings. If notifications are off, an alarm may not be able to ring at all. If full-screen alerts are off, it may appear as a small notification at the top of the screen that is easy to sleep through.

Do phone makers kill alarm apps?

Some do. The independent site dontkillmyapp.com tracks how manufacturers' own battery managers stop background apps, often beyond what standard Android does. On some Samsung phones, for example, it reports that apps you haven't opened for a few days can be put to sleep, and that this can stop alarms from working. Its fix is to add the app to "Never sleeping apps" and turn off options such as "Put unused apps to sleep". Xiaomi and other brands have similar "Autostart" and battery-saver settings. Menu names vary by phone and Android version, so the site's per-brand pages are the best guide.

Can Do Not Disturb or volume settings silence an alarm?

Yes. Google's own Clock help lists these causes: Do Not Disturb silenced the alarm, the alarm volume was too low, Battery Saver prevented it, or the ringtone was set to silent with vibration off. Do Not Disturb has a setting that allows alarms through; check that it is on. Also note that alarm volume is separate from media and ringtone volume on most phones.

What happens to alarms after a restart?

Android's documentation is blunt: "By default, all alarms are canceled when a device shuts down." Apps have to set them again when the phone starts, and they can only do that if you have opened the app at least once since installing it. A well-built alarm app handles this automatically. If yours doesn't, open it after a restart or a system update to make sure tomorrow's alarm is still set.

How to fix an Android alarm that doesn't go off

1. Allow notifications for your alarm app. Open Settings, then Apps, choose the app and turn notifications on.
2. Turn on exact alarms. In Settings, search for "Alarms & reminders" and allow the app.
3. Allow full-screen alerts. On Android 14 and newer, check that the app may show full-screen notifications, so the alarm appears over the lock screen.
4. Set battery use to Unrestricted. In the app's battery settings, choose Unrestricted (or "Don't optimize"), and remove it from any sleeping or restricted apps list.
5. Check your phone maker's extras. Look up your brand on dontkillmyapp.com and follow its steps, such as allowing autostart.
6. Let alarms through Do Not Disturb and raise the alarm volume. Make sure alarms are allowed in Do Not Disturb and that alarm volume is well above the lowest setting.
7. Test it. Set an alarm two minutes ahead, lock the phone, put it down and wait. Repeat after a restart.

How does Somnia handle alarm reliability?

We make Somnia, an Android sleep tracker and alarm, so this is the part we think about most. Here is what it does, and what it can't do:

• Somnia sets your wake alarm with Android's alarm-clock method, the one Doze lets through.
• It sets the alarm again after a restart, a time or time zone change, and an app update.
• Before bed, an "Alarm armed" check shows whether exact alarms, notifications, full-screen alerts and battery settings will let the alarm ring, with shortcuts to the right settings.
• If an alarm was missed, Somnia tells you the next time you open it, instead of pretending nothing happened.

What no app can do is overrule your own settings. If a phone maker's battery manager puts the app to sleep, or Do Not Disturb blocks alarms, the fix has to happen in the phone's settings. That is why the checklist above matters whichever alarm app you use.

Frequently asked questions

Why did my alarm not go off this morning when it worked yesterday?

Usually something changed overnight: a system update or restart cleared it, battery saving turned on, or the phone maker's battery manager put the app to sleep. Open the app, check its permissions and battery setting, and run a short test alarm.

Does the built-in Clock app work better than other alarm apps?

Your phone's built-in Clock app is a sensible backup while you troubleshoot. Any alarm app can only be as reliable as the settings it is given, so allow notifications, exact alarms and full-screen alerts, and set its battery use to Unrestricted.

Will my alarm ring if my phone is switched off?

Don't count on it. Many Android phones do not ring alarms while powered off, and Android clears alarms when the phone shuts down until the app sets them again. Keep the phone on and charging overnight.

This article is for general information and is not medical advice. If you have ongoing sleep problems, talk with a qualified clinician.