Yes, according to Google—but with an important qualification. Fitbit and Pixel Watch users in Public Preview are receiving updated sleep models that Google says provide an additional 15% increase in sleep-staging accuracy. Google’s published research reports average four-stage classification accuracy rising from 71% to 77%.
That does not mean every sleep measurement is 15% more accurate, and it does not make a Fitbit equivalent to a clinical sleep study. The update may also record more awakenings, change estimated sleep duration, or give you a different Sleep Score for the same night.
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What Fitbit changed
Google’s March 17, 2026 announcement describes a software and machine-learning update rather than a new sensor release. The updated models are designed to improve several parts of sleep tracking:
- Sleep-session detection: better separation between trying to sleep and actually sleeping, potentially improving estimated sleep onset, wake periods, and total sleep time.
- Sleep-stage estimation: improved classification of awake, light, deep, and REM sleep, including transitions between stages.
- Interruptions and naps: better recognition of brief awakenings, disrupted sleep, and naps, although results can vary by device and sleep pattern.
- Sleep Score: a redesigned presentation and scoring model that considers factors such as how long it took to fall asleep—not simply how much deep sleep you recorded.
Because the change is primarily an algorithm and app-experience update, results may change even when your tracker and its sensors have not.
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Google’s announcement says the new models are intended to use available movement and optical heart-rate-derived signals more effectively. It does not document the addition of new hardware to existing Fitbit devices.
What “15% more accurate” actually means
The consumer announcement says Public Preview users receive an additional 15% increase in sleep-staging accuracy. That is a claim about sleep-stage classification, not a universal improvement in sleep tracking, sleep duration, naps, or every individual night.
In a separate Google Research performance analysis, average four-stage accuracy increased from 71% to 77%. Cohen’s kappa, a measure of agreement beyond chance, rose from 0.56 to 0.63.
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The 71%-to-77% result is a six-percentage-point absolute increase, or roughly an 8.5% relative improvement over the old 71% figure. Google has not clearly explained how the consumer-facing 15% figure is calculated, so the two numbers should not be treated as interchangeable.
Why your score could get worse
An accuracy improvement can produce results that feel less flattering:
- More detected awakenings can reduce your apparent sleep quality.
- A later estimated sleep onset can reduce total sleep duration.
- Previously unnoticed interruptions may make the night look more fragmented.
- A revised weighting system can change the Sleep Score even if your body and sleep did not change.
A lower score therefore does not automatically mean the update failed or that you slept worse. It may mean the model is interpreting the night differently. Google has not clearly stated whether every historical night is recalculated, displayed with the new model, or left based on the previous algorithm, so historical comparisons may not be perfectly consistent.
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Independent coverage of an earlier Fitbit sleep update also reported that some users began seeing more recorded wakefulness. That is useful context for the reaction users may have, but it is not proof that every current Fitbit or Pixel Watch behaves identically.
Who gets the update?
Google specifically describes the 2026 improvement as available to Public Preview users. The announcement does not provide a complete model-by-model compatibility table, and availability may depend on your device, firmware, account, app version, region, and preview status.
Google’s support documentation describes improved sleep-tracking and Sleep Score algorithms for users with a connected Fitbit device or Pixel Watch. Do not assume that every legacy Fitbit automatically receives the new model.
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There is also a separate app transition: beginning May 19, 2026, Google says the Fitbit app becomes the Google Health app, with redesigned Sleep and Health sections. The app rebrand and interface change are related to the broader rollout but are not the same thing as the underlying sleep-model update. See Google’s support page for the transition details.
How to check and test the update
- Update the Fitbit or Google Health app through your phone’s app store.
- Install any available tracker or watch firmware update.
- Check the account, experimental-features, or Public Preview area for eligibility. Labels and enrollment paths may vary.
- Charge the device before bed and wear it snugly, while keeping it comfortable.
- Compare several nights rather than judging the model from one unusual night.
- Look at trends in bedtime, estimated sleep duration, wake time, and repeated patterns—not only the daily Sleep Score.
- Note whether your device, app, account, schedule, or wearing habits changed at the same time.
For a fair comparison, give the update multiple ordinary nights. Shift work, split sleep, irregular naps, illness, alcohol, travel, and a loose fit can all make night-to-night results difficult to interpret.
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| Metric | What it is useful for | Important limitation |
|---|---|---|
| Sleep versus wake | Broad trends across nights | Quiet wakefulness may be mistaken for sleep, while restless sleep may be classified as wake. |
| Total sleep duration | Tracking changes in schedule and consistency | It may not be exact to the minute. |
| Sleep stages | Observing broad, repeated patterns | Stages are estimates from movement and optical signals, not direct measurements of brain activity. |
| Naps and interruptions | Identifying possible changes in daytime or fragmented sleep | Short or irregular naps and brief awakenings may be missed or inconsistently classified. |
| Sleep Score | A convenient summary for personal trend tracking | It is a proprietary score and can change when the scoring model changes. |
| SpO2 or estimated oxygen variation | Flagging patterns worth discussing with a clinician | It is a separate feature and should not be confused with sleep-stage accuracy. |
Consumer wearables estimate sleep using signals such as movement and optical heart-rate-derived data. Polysomnography, the clinical reference method, also measures brain activity and other physiological signals. Google’s results support an algorithmic improvement; they do not establish that Fitbit sleep tracking is medical-grade.
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Fit, movement, skin contact, battery level, tattoos, and individual physiology can affect readings. Google says compatible hardware and software, sufficient battery, and appropriate sensor conditions are required for SpO2 collection, and notes that tattoos can affect red and infrared sensor accuracy. See the SpO2 support documentation.
Should you keep using Fitbit?
For most existing users, the sensible approach is to keep using it for long-term trends while treating individual stages and scores as estimates. The update appears to be a real model improvement, but no wrist wearable should be treated as a substitute for a sleep evaluation.
Consider other devices only for practical reasons such as comfort, battery life, phone compatibility, or training features. Apple Watch is mainly an iPhone option; Garmin is oriented toward sports and training; Oura offers a sleep-focused ring form factor. None should be assumed to deliver clinically accurate sleep staging without a directly comparable independent test of the specific device and algorithm.
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What remains unclear
Google’s public material does not fully specify the complete device and regional rollout, the exact calculation behind the 15% claim, or how all historical nights are handled. Those gaps matter when comparing old and new results. The safest interpretation is that eligible users may receive better sleep-stage and sleep-session estimates, not that every number on every Fitbit has become universally 15% more accurate.
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