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Guide

Going Deeper: Stages, Biometrics & Trends

Combine sound, stages, and watch sensors into a picture you can chart over months.

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You already record most nights, and the snore count alone has stopped surprising you. This guide takes you past that. It shows you how to feed the sleep-stage estimator clean data, fold in Apple Watch biometrics, read those signals together against your timeline, and pull everything into a spreadsheet so you can chart the trend across weeks and months. Treat every number here as a personal estimate, not a clinical reading. The point is to spot patterns in your own data and to ask better questions.

Set up for good stage data

Sleep stages in Snore Timeline come from sound. The app listens to your breathing rhythm, breathing regularity, and movement, then estimates whether you are in Light, Deep, or REM sleep, or Awake. Steady, metronome-like breathing points toward Deep sleep, moderate regularity toward Light, and more irregular breathing toward REM. Because the whole estimate rides on hearing your breath, your setup decides how good the data is.

Three things give the estimator the clearest signal:

  1. Close placement. Keep the phone about 1 to 2 feet from your head. Breathing fades fast with distance, and faint breathing is what stages depend on. The full reasoning lives in Getting Started.
  2. A quiet room. Fans, white noise machines, air purifiers, HVAC, and a TV left on mask the breathing the app needs. When breathing drops below what the app can resolve, that stretch reads as Silence rather than a stage. Silence still counts as restful sleep, but you lose stage detail for that window.
  3. A consistent baseline. The app establishes your personal breathing baseline, your typical rate and regularity, during the first part of the recording, then measures the rest of the night against it. Respiratory rate settles after roughly the first 10 to 15 minutes of detected sleep. Record the same way each night so that baseline stays comparable across your trend.

Longer recordings sharpen the estimate, since several hours let the app observe more complete sleep cycles. The mechanics of how each signal maps to a stage are covered in Sleep Stages, and the hypnogram section explains how to read the stage chart itself.

Tip

If you keep seeing long Silence bands, your breathing is reading too soft. Move the phone closer, switch to Standard quality for richer audio, and cut one source of room noise. Each change gives the stage estimator more to work with.

Connect your watch and Health

An Apple Watch adds a second, sensor-based view that audio cannot reach. When a watch reports sleep-stage data for the night, Snore Timeline uses the watch's Deep and REM percentages for your sleep score in place of its own audio-derived estimates, since a wrist sensor measures those stages more accurately. Without a watch, the app falls back to its breathing- and movement-based estimates.

A paired watch also surfaces biometrics on your summary and in your export:

  • Heart rate, including average, minimum, maximum, and a resting estimate.
  • Heart rate variability (HRV).
  • Blood oxygen (SpO2). With watch SpO2 data, the app can show the percentage of the night spent below 95% oxygen saturation and your lowest reading.
  • Respiratory rate from the watch, alongside the app's own audio estimate.
  • Wrist temperature, which appears in the per-night aggregates.

This data flows through Apple Health. Snore Timeline reads watch biometrics from Health and works fully with microphone access alone, so the watch connection is an addition rather than a requirement. Health and other permissions come up only when you turn those features on. Setup steps, the full biometrics list, and notes on other wearables live in Apple Watch & Biometrics, with details on the data exchange in the Apple Health and other wearables sections.

Nightly summary with watch biometrics alongside audio metrics
Watch biometrics sit beside the app's audio metrics on the nightly summary.

Read the full picture

One signal in isolation tells you little. The value comes from reading them together for a single night, then carrying that habit across nights. Work through the summary in this order:

  1. Start with the hypnogram. See the shape of the night: when Deep clustered, when REM grew toward morning, where you woke. Snore Timeline targets Deep sleep around 13 to 23 percent of your sleep and REM around 20 to 25 percent as general guidelines.
  2. Lay snoring and disruptions over it. Open the episode list and note when the loud stretches landed. Did heavy snoring coincide with lighter stages or with a cluster of breathing disruptions? The timeline lets you jump to any moment and play it back through Timeline & Playback.
  3. Add the biometrics. Check whether your watch SpO2 dipped during the same window, or whether heart rate stayed elevated through a noisy stretch. These are correlations to notice, not causes to conclude.
  4. Read the sleep score last. The 0 to 100 score rolls these factors into one number. Duration carries the most weight, with 7 or more hours treated as ideal; Deep and REM percentages, efficiency, time to fall asleep, awakenings, bedtime consistency, snoring, and breathing disruptions all feed in. Tap the score badge for a factor-by-factor breakdown. The Sleep Score page explains each input.

Snore Timeline also tracks a Sleep Bank against a 7-hour nightly goal, so you can see accumulated sleep debt rather than judging a single night. Pair that with the weekly trends view and your sleep deficit to read direction over time instead of reacting to one rough night.

Honest limits

Important

Every metric in this guide is an estimate for personal insight, not a clinical measurement or a diagnosis. Snore Timeline derives stages, respiratory rate, and breathing disruptions from sound, and reads heart rate and SpO2 from a consumer wearable. Clinical sleep staging uses brain waves, eye movement, and muscle activity, signals that audio cannot capture, so an audio-based stage estimate runs around 70 percent agreement with polysomnography as a rough figure, not a guaranteed accuracy. Acoustic disruption counts skip events that produce no audible recovery, so treat them as a conservative floor. The app does not diagnose sleep apnea or any condition. If your trends concern you, or you notice daytime sleepiness, morning headaches, or a partner reports pauses in your breathing, share the recordings and your export with a healthcare provider and let them interpret it.

Read across nights, not within one. A single rough reading often reflects a noisy room or a phone too far away rather than your sleep. The trend is where the signal lives. The accuracy notes for stages and the guidance on when stages do not appear are worth reading before you put too much weight on any one figure.