Updated
Most alarm advice is about the morning. This is about the 30 seconds before you sleep, which is the only time you can still fix anything. Here is the short checklist worth running.
1. Turn the ringer volume up. Not the media volume, the ringer. On iPhone they are separate, and if the ringer is down, the alarm plays too quietly to hear even when the phone is not on silent. Settings, then Sounds and Haptics.
2. Read tonight's Focus schedule. A Sleep or Do Not Disturb schedule can mute alarms that are not allowed to break through. Open Settings, then Focus, and check what is actually set to run overnight.
3. Disconnect your headphones. If AirPods or a Bluetooth speaker are paired, the alarm can play there instead of on the phone. If they are on the nightstand and you are not, that is a silent alarm.
4. Check battery settings, on Android especially. On Samsung, Xiaomi, and others, battery optimization can stop an alarm app overnight, often after a system update. Set your alarm app to unrestricted and turn off the option that puts unused apps to sleep.
5. Confirm the alarm is on for the right day. Sounds obvious. It is still the most common one, a one off alarm that was set for today, or repeat days that do not include tomorrow.
That is the whole list. The catch is that you have to remember to run it, every night, and none of these problems show up on their own. The alarm just looks set.
That is why we made Snora. It is an alarm you set like any other, and before you sleep it checks its own setup, the permissions and settings it needs to ring, then shows one status, Safe, Caution, or Risk, so you can see a problem tonight instead of finding out tomorrow. It is a status, not a score to chase, and it is not a promise about your morning. The alarm and the check are free, and no account is needed.
Whether you use the checklist or the app, the idea is the same, see whether your alarm will ring before you close your eyes, not after it does not.
FAQ
Why didn't my alarm go off even though it was set?
An alarm that looks set can still stay silent because the ringer volume was low, a Focus or Do Not Disturb schedule muted it, Bluetooth headphones were connected, or battery optimization stopped the app overnight on Android. None of these leave a warning on the alarm screen, so the alarm looks ready while one setting quietly blocks it. Reviewing each one before you sleep is how you catch it in time, and it is the routine Snora automates by checking the permissions it needs and guiding you through the rest before showing a single Safe, Caution, or Risk status.
Will my alarm still ring if my phone is on silent?
On iPhone, an alarm set in the Clock app rings even when the phone is on silent or vibrate, but how loud it plays follows the ringer volume, not the media volume. If the ringer is turned down, the alarm can be too quiet to wake you, so raise it under Settings, then Sounds and Haptics. On Android the behavior varies by manufacturer, so it is worth testing what your specific phone does.
Does an alarm work when Bluetooth headphones are connected?
If AirPods or a Bluetooth speaker are still paired at bedtime, the alarm can play through them instead of the phone speaker. That sends the sound to whatever device is on the nightstand rather than to the one by your bed. Disconnecting or powering off the headphones before sleep keeps the alarm on the phone where you can hear it.
How do I stop battery saver from turning off my alarm on Android?
Set your alarm app to unrestricted and turn off the option that puts unused apps to sleep, since Samsung, Xiaomi, and similar phones tend to pause background apps overnight. You can find these under Settings, then Battery, though the exact wording differs by brand. It is worth rechecking after a system update, because updates sometimes reset the setting back on.