iPhone alarm not going off: the real causes

Start with Attention Aware Features. On any Face ID iPhone, if the TrueDepth camera decides you are looking at the screen, iOS *lowers the volume of your alarm* — and a half-open eye at 6:40am counts as looking. It is on by default, almost nobody knows it exists, and it is the single most common reason an alarm "went off" and you did not hear it. Settings → Face ID & Passcode → Attention Aware Features → off.

If that is not it, work down the list below in order. And one thing to get out of the way immediately, because half the internet is wrong about it: the silent switch does not mute your iPhone alarm. It never has. The Clock app rings in silent mode, in Do Not Disturb, and in every Focus. If your alarm was silent, something else did it.

The seven causes, in the order they actually happen

Cause 7 is the one nobody tells you about

If you were relying on a third-party alarm app rather than the Clock app, the rules are completely different, and worse. Until iOS 26, a third-party alarm was not a real alarm. It was a local notification plus a background-audio trick, which meant iOS was entitled to mute it under a Focus, delay it, or terminate the app outright if you swiped it out of the app switcher. This is why Alarmy’s own support documentation asks users to disable silent mode and Do Not Disturb — not because the developers are careless, but because that was the only defence available.

Apple fixed this in iOS 26 with AlarmKit, a framework that lets an app schedule a genuine system alarm. An AlarmKit alarm rings through silent mode, through Do Not Disturb, through every Focus, and it rings even if the app has been force-quit — because the system, not the app, owns the alarm. Risly is built on it. That is the honest version of the claim: not "unlike your iPhone" (your iPhone was always fine), but unlike other alarm apps.

Four things that do NOT stop your alarm

Half the advice on this topic is people fixing things that were never broken. To save you the evening:

• The silent switch / silent mode. Does not mute the Clock alarm. Never has. Stop flicking it back and forth.
• Do Not Disturb and Focus modes. The Clock alarm rings through all of them, including Sleep Focus. That is the entire design of Sleep Focus.
• Low Power Mode. Alarms still fire. It throttles background activity, not the system alarm.
• Scheduled Summary. It delays notifications. An alarm is not a notification, so it is untouched.

What *does* touch your alarm: attention detection, the ringer volume slider, and — if you are using a pre-iOS-26 third-party app — the operating system deciding it no longer needs to keep that app alive. Everything else on the internet’s checklist is noise.

What about the recurring iOS "quiet alarm" bug?

Every iOS release cycle produces a wave of reports that alarms have gone silent or quiet. Some of those are genuine regressions Apple has patched. The large majority, once people dig in, turn out to be Attention Aware Features (cause 1) or the ringer volume slider (cause 2). Update to the latest iOS, then work the list above before you conclude your phone is broken.

The pattern that makes people suspect a bug is that the alarm works for weeks and then fails once, on the worst possible morning. That is not what a software bug usually looks like. It is what an attention-detection feature looks like: it fails specifically on the mornings you half-woke, glanced at the phone, and went back under. In other words, it fails on exactly the mornings you needed it, which is why it feels malicious. It is not malicious. It is a default, and you can turn it off in about eight seconds.

Do the two-minute test tonight before you trust anything: settings changed, phone face-down, alarm set, do not look at it. An alarm you have not tested is a promise, not a plan.

If the alarm rang and you turned it off anyway

This is the other half of the traffic on this query, and it deserves saying plainly: check your phone. Most of the time the alarm was dismissed, not missed — within seconds, by you, with no memory of it. Nothing in this settings list will help, because nothing was wrong with the phone. That is a different problem and we wrote it up separately in I keep sleeping through my alarm.

The fix there is an alarm that cannot be dismissed by a sleeping person: Risly has no snooze button and no stop button. The alarm ends when you complete a mission — scan an object across the house with the camera, solve chained math problems, shake the phone, or do push-ups the camera counts. It needs iOS 26 or later, and there is no Android version.