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Android Alarm Not Going Off: An Ordered Checklist

Last updated August 8, 2026

Android alarm not going off: an ordered checklist

Short answer: On Android, an alarm that does not fire is usually a power management problem rather than a bug. The system's Doze and app standby features, plus far more aggressive versions of the same idea added by manufacturers such as Samsung, Xiaomi, OnePlus and Huawei, will suspend a background app overnight and take its scheduled alarm with it. The built-in clock app is normally exempt from this; third-party alarm apps very often are not. Work through the checklist below in order, and note that setting names and behaviour differ by manufacturer and Android version, so where a name does not match your phone the underlying setting usually exists somewhere nearby.

If you are on an iPhone, the companion piece is why your phone alarm didn't go off, which covers the causes common to both platforms.

The ordered checklist

Do these in sequence. The first four fix the large majority of cases.

1. Exempt your alarm app from battery optimisation

Doze mode, introduced in Android 6, defers background work when a device has been stationary and unused for a while. Android also sorts apps into standby buckets based on how often you use them and restricts the rarely used ones harder. An alarm app you open once a week is exactly the profile that gets throttled.

Find your alarm app in Settings, open its battery setting, and set it to unrestricted or exclude it from optimisation. On stock Android this is usually App info, then Battery, then Unrestricted.

2. Undo your manufacturer's app killer

This is the step that most often matters and the one most guides skip. The community-maintained reference site Don't Kill My App has documented this behaviour for years and consistently ranks Huawei, Xiaomi, OnePlus, Samsung and Meizu among the worst offenders, with a long tail of others including Oppo, Vivo, realme, Asus, Sony and Motorola.

What to look for by brand:

These settings have a habit of resetting after a system update, so if an alarm fails months after you fixed it, check them again first.

3. Confirm the app still has permission to schedule exact alarms

This one is newer and catches people who never changed a setting.

Android needs a specific permission to fire an alarm at an exact moment rather than in a convenient window. Since Android 14, the SCHEDULE_EXACT_ALARM permission is no longer granted automatically on install to newly installed apps targeting Android 13 or later, and Google's own developer documentation notes that apps restored through backup-and-restore have it denied. Genuine clock and calendar apps are supposed to use a different permission that is granted at install, but not every app has migrated, and an app without the permission will fall back to inexact alarms that can fire late or not at all.

Look for Special app access, then "Alarms & reminders", and confirm your alarm app is allowed. This is also the reason an alarm app that worked perfectly on your old phone can behave differently on a new one restored from a backup.

4. Check app hibernation has not stripped the app

Separately from battery optimisation, Android hibernates apps you have not opened for months. On Android 12 and above this resets runtime permissions, blocks background jobs and alerts, blocks notifications and clears the cache. Google backported a permission-resetting version of this to Android 6 through 10 via Play services.

The setting sits in App info and is named differently by version: "Pause app activity if unused" on Android 13 and later, "Remove permissions and free up space" on Android 12, and "Remove permissions if app isn't used" on Android 11. Turn it off for your alarm app.

5. Check Do Not Disturb, Modes and Bedtime mode

Alarms from the system clock app are normally exempt from Do Not Disturb by default. Two things break that assumption. First, the exemption is a setting, and it can be off — look under Do Not Disturb for the allowed exceptions and confirm alarms are permitted. Second, a third-party alarm app that produces its own notification sound rather than a system alarm may not be covered by the alarm exemption at all.

Also check for automations you set up and forgot: scheduled Modes, Bedtime mode in Digital Wellbeing, and manufacturer routines such as Samsung's Modes and Routines or Bixby routines can all switch profiles overnight.

6. Set the alarm volume channel explicitly

Android keeps separate volume streams for ring, media, notifications and alarms. Turning media volume to zero for a video does not touch the alarm stream on stock Android, but some manufacturer skins link streams in non-obvious ways, and some have a setting to sync ringtone and alarm volume.

Press a volume key, open the full slider panel, and set the alarm slider deliberately. While you are there, open the alarm itself and confirm a tone is selected rather than None or a silent tone. An alarm set to vibrate-only with a silent tone is a common self-inflicted failure.

7. Rule out Bluetooth audio routing

If your phone stayed paired to earbuds, a speaker or a car overnight, the alarm may have played to that device. Sleep earbuds are the classic case: the alarm plays perfectly into an earbud that fell out at 1am. Turn Bluetooth off at night or confirm the active output before bed.

8. Rule out scheduled power off and overnight reboots

Several manufacturers, including Samsung and Xiaomi, offer scheduled power on and off. If the phone is powered down at your alarm time, behaviour varies: some devices will power on for an alarm and many will not, so do not rely on it. Check for a scheduled power-off you set up months ago.

Overnight system updates reboot the phone, and while the built-in clock reliably reschedules its alarms after a restart, some third-party apps do not until you open them. If a failure coincided with an update, that is likely the cause.

9. Check the boring things

The AM/PM error is unglamorous and extremely common; switching the phone to 24-hour time eliminates the whole category. Check the repeat days actually match your week, and whether the alarm is set to repeat at all. Check automatic time zone if you have travelled or live near a border. Check the phone did not simply go flat, and that the charging cable was seated.

10. Consider that it fired and you turned it off

Once the first nine are eliminated, this is what is left, and it is the most common single cause across all phones. Motor control returns before memory formation does, so you can dismiss an alarm while functionally asleep and form no memory of it. Most clock apps keep an alarm history, and your screen-on time will usually show activity at the alarm time. Turning off your alarm in your sleep covers the mechanism.

What this checklist does not fix

It fixes delivery. It does not fix arousal.

If you have worked through all ten and the alarm demonstrably fires, at volume, into a quiet room, and you still do not wake, then nothing in Android settings is your problem. That is habituation to a familiar sound, sleep debt, or being a genuinely heavy sleeper, and it is addressed on its own terms in I sleep through every alarm and why loud alarms don't work for heavy sleepers.

It also will not make Android reliable in the way a single-purpose device is reliable. Every item on that list exists because your alarm is a feature bolted onto a general-purpose computer that manages its own power, revokes its own permissions, routes its own audio and updates itself while you sleep. You can configure all of it correctly and a system update can undo some of it. If the wake-up genuinely cannot be missed — a flight, a shift, an exam — the honest advice is redundancy: two independent devices, at least one of which is not a phone.

That is the narrow case where a dedicated device earns its place. Silent Wake is a wrist-worn vibration alarm with no app, no Bluetooth and no phone pairing, which means there is nothing to route, no background process to suspend and no permission to revoke. Two alarms are set on the device itself, and it runs up to 14 days per charge. It also has no speaker, so it is not for everyone, and if your problem turned out to be a Samsung sleeping-apps setting, just fix the setting.

Common questions

Why does my Android alarm not go off when the phone is locked or the screen is off?

Almost always power management. Android's Doze mode and app standby restrict background work when the device has been idle, and manufacturer skins from Samsung, Xiaomi, OnePlus and Huawei add far more aggressive versions that can suspend an app entirely after a few days of not opening it. The built-in clock app is usually exempt; third-party alarms often are not. Exclude the app from battery optimisation and remove it from any manufacturer sleeping-apps list.

Do alarms work in Do Not Disturb on Android?

Usually yes for alarms set in the system clock app, because alarms are an exception to Do Not Disturb by default on stock Android. That exception is a setting, though, so it can be switched off, and a third-party app that plays a notification sound rather than a true alarm may not be covered by it at all. Check the Do Not Disturb exceptions list, and check for scheduled Modes or Bedtime mode changing your profile overnight.

Will my Android alarm go off if the phone is switched off?

Do not count on it. Some manufacturers have historically included a feature that powers the device on for a scheduled alarm, but this is not universal, it varies by model and Android version, and it does not apply to a phone that shut down because the battery went flat. If you have a scheduled power-off configured, disable it. For a wake-up that matters, use a device that is definitely powered on.

Why did my alarm app stop working after I got a new phone?

Most likely the exact alarm permission. Since Android 14, the permission that lets an app fire an alarm at a precise time is not granted automatically to newly installed apps targeting recent Android versions, and Google's documentation notes it is denied for apps restored from a backup. Check Special app access, then "Alarms & reminders", and allow the app. Then redo the battery optimisation exemption, since none of those settings transfer with a restore.

Should I just use the built-in clock app?

For reliability, generally yes. The manufacturer's own clock app is nearly always exempt from that manufacturer's battery optimisation and app-killing behaviour, holds the exact alarm permission by default, and reschedules correctly after a reboot. Third-party alarm apps offer features the built-in one does not, and if you need those, budget for keeping the app whitelisted after every system update. Using the built-in clock removes several of the failure modes on this page permanently.

Related reading

Setting names and behaviour vary by manufacturer, skin and Android version. Where a name does not match your phone, the equivalent setting usually exists under a different label.