For a genuinely heavy sleeper, the failure mode is not "the alarm was too quiet." It is that the alarm was answered and dismissed by a brain that was not conscious enough to remember doing it. Volume does not fix that — the interaction does.
What to actually look for
- A wake step that requires more than a reflex swipe — a full-screen prompt that has to be deliberately acknowledged, not just silenced.
- A signal to someone else — the only way to know an alarm did not work is if a second person finds out.
- Delivery that does not depend on the ringer — the alarm channel, not the notification channel, so silent mode and Do Not Disturb do not quietly defeat it.
- Honesty about limits — anything that claims to guarantee a wake-up is overstating what a phone app can control.
How WakeKids fits this
WakeKids covers the first three directly: a parent can trigger or schedule the alarm remotely, the wake screen plays on the alarm channel so silent mode does not mute it, and the parent is notified the moment the screen is acknowledged — or alerted if it is not. It does not try to claim the fourth. Delivery still depends on the phone being on, connected, and correctly permissioned, and WakeKids says so directly rather than promising more than a phone app can deliver.
If a heavy sleeper is the actual problem you are solving for, that combination — forced interaction plus a second-person signal — is what to prioritize over raw volume, on WakeKids or on anything else you evaluate.