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Guide

Going Deeper: Stages, Biometrics & Trends

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

On this page

You already record most nights, and the snore count has stopped surprising you. This guide goes past that. It covers 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. None of it is a clinical reading. The point is to spot patterns in your own data and ask better questions.

Set up for good stage data

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

A few 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 is in Getting Started.
  2. A quiet room. Fans, white noise machines, air purifiers, HVAC, and a TV left on cover up the breathing the app needs. When breathing drops below what the app can make out, that stretch reads as Silence instead of a stage. Silence still counts as restful sleep, but you lose the stage detail for that window.
  3. A consistent baseline. The app works out 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 give the app more complete sleep cycles to look at. How each signal maps to a stage is covered in Sleep Stages, and the hypnogram section explains how to read the stage chart.

Tip

If you keep seeing long Silence bands, your breathing is coming through 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 can't 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 estimates, since a wrist sensor measures those stages more accurately. Without a watch, the app falls back to its breathing and movement estimates.

A paired watch also adds biometrics to your summary and 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.

All of this comes through Apple Health. Snore Timeline reads watch biometrics from Health, and it works fully with microphone access alone, so the watch is an extra and never a requirement. Health and other permissions only come up when you turn those features on. Setup steps, the full biometrics list, and notes on other wearables are 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 next to the app's audio metrics on the nightly summary.

Read the full picture

One signal on its own tells you very little. The value comes from reading them together for a single night, then doing that night after night. Work through the summary in this order:

  1. Start with the hypnogram. Get the shape of the night. When Deep clustered, when REM built toward morning, where you woke. Snore Timeline treats 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 line up with lighter stages, or with a cluster of breathing disruptions? The timeline lets you jump to any moment and play it back. See Timeline & Playback.
  3. Add the biometrics. Check whether your watch SpO2 dipped during the same window, or whether heart rate stayed high through a noisy stretch. These are correlations to notice. They don't prove a cause.
  4. Read the sleep score last. The 0 to 100 score rolls all of this 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 too. Tap the score badge for a factor-by-factor breakdown. The Sleep Score page explains each input.

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

The limits

Important

Every metric in this guide is an estimate for your own insight. None of it is a clinical measurement or a diagnosis. Snore Timeline works out 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, which audio can't capture, so an audio-based stage estimate lands around 70 percent agreement with polysomnography as a rough figure, with no guarantee. Disruption counts from audio skip events with no audible recovery, so treat them as a conservative floor. The app doesn't diagnose sleep apnea or any condition. If your trends worry you, or you notice daytime sleepiness, morning headaches, or a partner mentions pauses in your breathing, share the recordings and your export with a healthcare provider and let them interpret it.

Read across nights. A single rough reading often comes down to a noisy room or a phone too far away, and says nothing about your sleep. The trend is what carries the signal. The accuracy notes for stages and the guidance on when stages don't appear are worth reading before you lean on any one figure.