Stage breakdown
Deep, REM, core, awake. Proportions matter more than absolutes — the shape of the night is the signal.
Sleep Analysis · Apple Watch sleep tracker
What your sleep
actually did.
Your Apple Watch already tracks sleep. Body Insights reads what it recorded — stages, efficiency, overnight glucose — and tells you, in plain language, what your body actually recovered.
Get Body Insights
Free for core features.
Eight hours in bed. You wake up cement-heavy.
The chart says you slept. Your body says you didn't. Both are honest.
Sleep isn't a duration. It's a process — stages cycling, glucose stabilizing, your nervous system winding down hour by hour. When any of those is disrupted, you logged the time and missed the work. Apple Watch records most of it. Most apps don't translate it.
Body Insights does. Once you wake, you get one sentence: "Last night was lighter than usual. The drop in deep sleep tracked your late dinner." The score is there if you want it. The recommendation is in words.
The part nobody else does: your overnight glucose.
If you wear a CGM — Stelo, Dexcom, Libre — Body Insights folds your overnight glucose curve into the sleep read. Most readiness apps stop at HRV and stages. The hours your blood sugar spent climbing or crashing get ignored, even though your nervous system spent the same hours managing them.
Patterns like the dawn phenomenon, REM-stage spikes, or a late-night reactive drop get surfaced. Each one tied back to what you ate, when, and how you woke up feeling.
If you don't wear a CGM, this layer drops out cleanly and the rest of the read still works.
The shape of a night.
Not a score. The architecture itself — deep early, REM growing toward morning, brief awakenings woven through.
A typical night's shape — what Body Insights reads as a pattern, not a verdict.
Read your sleep, tomorrow morning
Free for core features. No card needed.
For people who want the science.
Everything below is what an honest Apple Watch sleep tracker should tell you. If you're shopping comparisons, you're in the right place.
What we read from your Apple Watch.
Reads sleep data from Apple Health — the same data your Apple Watch already writes there overnight.
Sleep efficiency
Time asleep divided by time in bed. The single most under-read sleep metric.
Fragmentation
How many awakenings, how long each one lasted. A quiet seven hours is a different thing than a restless seven hours.
Overnight glucose
If you wear a CGM. Glucose stability fused with sleep stages, surfacing patterns like dawn phenomenon.
ODI & breathing
Oxygen desaturation index plus respiratory rate trend. Flags patterns worth bringing to your doctor — we don't diagnose.
Plain-language insight
One sentence in the morning that ties last night to the day before it. Not a score. A summary.
How accurate is the Apple Watch sleep tracker?
Better than most consumer wearables, but not a sleep lab. Validation work in recent years points to high-80s correlation with polysomnography for total sleep time and reasonable agreement on stage proportions.
For a single night against a lab study, expect minor disagreement. For trends across a week or a month, the signal is strong. That's the lens Body Insights uses — each night as a data point in a pattern, not a verdict.
The 14-day shape of your sleep — when deep dropped, when REM compressed, which nights your wrist temperature climbed — is where the actually useful information lives.
Apple Watch sleep tracker vs Whoop, Oura, the built-in app.
You're probably here because one of these didn't fit. So this is the honest comparison.
| Apple Sleep app | Whoop / Oura | Body Insights | |
|---|---|---|---|
| Sleep stages | Yes | Yes | Yes |
| Sleep efficiency | No | Yes | Yes |
| Overnight glucose fusion | No | No | Yes |
| Plain-language summary | No | Partial | Yes |
| Subscription | None | $6–30 / month | Free for core |
| Extra hardware | None | Ring or strap | None |
Whoop and Oura are real products built by careful people. They were built for a different reader — athletes tuning training load, biohackers chasing optimization. If yours is a body whose recovery doesn't follow a training cycle, this one was built for you.
Questions you're probably asking.
Is Apple Watch sleep tracking accurate?
For trend reading across a week, yes — validation work points to good agreement with polysomnography. For a single night against a lab, expect minor disagreement.
Can the Apple Watch detect sleep apnea?
It flags potential breathing disturbances. Body Insights surfaces these via ODI patterns. We don't diagnose — persistent patterns are worth bringing to your doctor.
What's the best Apple Watch sleep tracker app?
If you want a stage chart, Apple Sleep covers that. If you want what last night did for your body — especially with overnight glucose or chronic illness in the story — that's what we built.
Apple Watch sleep tracker vs Whoop?
Whoop adds strain framing for athletes. Body Insights adds overnight glucose, plain-language summaries, and tuning for variable baselines. No strap, no monthly fee.
Do I need a CGM?
No. Without one, the metabolic-sleep layer drops out and the other reads carry the morning summary. With one, you get a layer no other sleep app reads.
How much does it cost?
Free for core sleep features. A premium tier adds metabolic-sleep fusion and deeper analytics. No card needed to start.
Your sleep data stays yours.
On-device. No account. No subscription required. No data sold. Ever.
- Reads from Apple Health
- Stays on your iPhone
- You choose what to share
Read your sleep, tomorrow morning.
Free for core sleep insights. Premium adds metabolic-sleep fusion.
