Apple Watch sleep stages: what a phone breathing report adds.

Apple Watch estimates time spent Awake and in REM, Core and Deep sleep. Core is lighter non-REM sleep; Deep is a deeper non-REM stage, while REM is associated with vivid dreaming. The chart helps you see how these estimated stages are distributed through a night and how your patterns change over time.

If your question is about breathing, SomniSense, a sleep apnea detector app, provides its own phone-based analysis of possible pauses and shallow-breathing patterns. Its audio methods were studied using recordings paired with labels from clinical sleep studies (PSG). You can return to marked moments, inspect the waveform and listen to available sound; those records do not confirm REM, Core or Deep sleep.

Different signals, different outputs

Start with one completed Night Report: choose a marked moment, check its estimated time and duration, then listen before and after it without searching hours of recording. A compatible phone is enough; a watch is not required.

Neither output should be used to explain the other. Apparent agreement is not clinical confirmation, and disagreement does not prove that either product failed.

How to compare responsibly

• Compare the same date and first check that both products captured enough of the night.
• Read each value inside its maker's documented definition.
• Look for repetition instead of treating one dramatic night as a verdict.
• Do not infer airflow, oxygen, airway closure, clinical events, or diagnosis from the combination.