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Yes, Fitbit has intentionally changed how it estimates sleep. The July–August 2025 rollout and the separate 2026 Public Preview update can report more awake time, less total sleep, different REM and Deep totals, and a lower Sleep Score—even when your routine and device have not changed.
That does not automatically mean your Fitbit is broken or that your sleep suddenly worsened. The newer system may be reclassifying the same sensor data, including brief awakenings that the previous model missed. Fitbit’s validation results indicate improved sleep-stage classification, but individual nights remain estimates rather than clinical measurements.
The short version
| What you see | Most likely explanation |
|---|---|
| More awake time | Brief awakenings may now be counted. |
| Less reported sleep | Time spent in bed is being separated more carefully from time actually asleep. |
| Different REM, Light, or Deep totals | Sleep-stage boundaries have changed. |
| A lower Sleep Score | The measured inputs and, in 2026, the scoring presentation or formula may have changed. |
| Older nights look different | Some users report historical changes, although Fitbit has not clearly documented the full scope of any recalculation. |
| An entire night is missing | Check syncing, charging, fit, heart-rate data, or hardware before blaming the algorithm. |
There are two sleep updates, not one
It is easy to describe this as “the Fitbit update,” but the evidence points to separate changes.
- July–August 2025: Fitbit rolled out updated tracking technology. In an August 1, 2025 community announcement, Fitbit warned that sleep stages, sleep time, and awake time could change because the new system detects brief awakenings that the old system missed.
- March–May 2026: Google announced another sleep-model update for Public Preview users. It said the newer model better distinguishes trying to sleep from actually sleeping, captures interruptions, naps, and stage transitions, and provides an additional 15% increase in sleep-staging accuracy. That is a company-reported validation result, not a guarantee for every user or every metric.
- May 19, 2026: The Fitbit app began transitioning to the redesigned Google Health app, and Fitbit Premium was renamed Google Health Premium. The app redesign is related to how information is presented, but it should not be confused with the underlying 2025 and 2026 sleep-model changes. See Google’s transition guidance.
Why Fitbit may now say you were awake longer
Sleep trackers estimate sleep indirectly from signals such as movement and heart rate. They do not directly observe consciousness. If an older algorithm treated a short movement or heart-rate change as continued sleep, while the newer model labels it as an awakening, the same night can produce a different result.
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For example, someone might spend eight hours in bed and previously be shown seven hours 40 minutes asleep. If the new model identifies several short awakenings, it could report less sleep and more awake time without the person’s actual night changing.
The update can affect:
- total sleep duration;
- awake minutes and interruptions;
- the estimated time needed to fall asleep;
- REM, Light, and Deep-stage boundaries;
- nap detection;
- Sleep Score components and trend lines.
A lower score therefore does not prove that sleep quality became worse. Three different things can be happening: the system may have changed what it measured, Fitbit may have changed how it combines those measurements into a score, or your sleep may genuinely have changed. A sudden score drop after an algorithm rollout should not be treated as proof of a sudden health change without considering all three possibilities.
Is the new system actually more accurate?
Fitbit’s published evidence supports improvement over its earlier models in the company’s validation testing. Its 2026 technical document reports four-stage sleep-staging accuracy of:
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| Model | Reported accuracy | Cohen’s kappa |
|---|---|---|
| Original model | 0.67 | 0.47 |
| July 2025 model | 0.71 | 0.56 |
| Newer model | 0.77 | 0.63 |
The reported test set included 50 participants and compared the models with gold-standard sleep measurements. The document also describes remaining errors, particularly confusion between Deep and Light sleep and between Wake and Light sleep. On average, 69% of Wake epochs were correctly labeled as Wake.
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The accurate conclusion is therefore qualified: Fitbit’s evidence indicates that the newer algorithm performed better than its previous models on the reported validation set. It does not mean every individual night, sleep stage, or user result is more accurate. Consumer wearables remain estimates and do not replace polysomnography or a clinical sleep evaluation.
What the 2026 Sleep Score changes
Google describes the redesigned Sleep Score as more transparent, holistic, and actionable. The company says the newer experience considers not only how much sound sleep a person received, but also how long it took to reach it and other aspects of rest.
That means a score can change even if the reported total sleep time changes only slightly. More weight on sleep latency, interruptions, consistency, or newly classified stages can create a discontinuity in the trend line. Do not compare a score from before the model change with a score from afterward as though the underlying measurement system were identical.
Google’s “additional 15%” claim refers specifically to sleep-staging accuracy for Public Preview users. It does not establish a 15% improvement in total sleep duration, awake time, naps, Sleep Score, every device, every country, or every user.
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Which devices were included in the 2025 rollout?
Fitbit’s community announcement listed the following devices. This is Fitbit’s announced rollout list, not a guarantee that every device received the change at the same time or with identical behavior.
Smartwatches
- Versa Lite, Versa 1, Versa 2, Versa 3, and Versa 4
- Sense and Sense 2
- Pixel Watch, Pixel Watch 2, Pixel Watch 3, and Pixel Watch 4
Trackers
- Alta HR and Inspire HR
- Inspire 2 and Inspire 3
- Luxe
- Charge 2, Charge 3, Charge 4, Charge 5, and Charge 6
The 2026 model has a different scope. Google describes it as a staged Public Preview experience for compatible Fitbit and Pixel devices. Eligibility can depend on enrollment, account, geography, app state, device compatibility, and rollout timing.
Is this a firmware update?
The available announcements point primarily to a tracking-model and data-processing change, rather than one universal firmware feature update. Fitbit described “updated tracking technology” without publishing a single firmware version covering every affected result. Google described the 2026 change as a machine-learning model and staged Public Preview rollout.
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Did Fitbit recalculate historical sleep?
Some users report that older nights changed after the rollout, including in Fitbit’s community discussions. However, Fitbit’s public announcements do not clearly specify whether all historical nights were recalculated, only recent nights were reprocessed, or whether original values remain available internally.
Accordingly, treat historical changes as a reported behavior rather than a documented universal policy. If long-term records matter, save screenshots or export available health data before changing devices or accounts. An export should not be assumed to preserve both the original and revised versions of every value.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How to work out whether you have an algorithm change or a device problem
- Identify the data source. Note your device model, phone operating system, whether you joined Public Preview, whether you use the Fitbit app or Google Health app, and the date the change began.
- Compare several nights. Review three to seven similar nights before and after the change. Check awake minutes, sleep onset, REM and Deep estimates, naps, and individual Sleep Score components rather than relying on one unusually good or bad night.
- Check tracking conditions. Wear the device snugly but comfortably, keep the sensor in contact with your skin, charge before bed, sync after waking, and look for gaps in heart-rate data.
- Preserve important records. Screenshot key trends or export available data if you are concerned about future recalculation. This will not necessarily restore old scores.
- Use support for persistent failures. Missing nights, repeated sync failures, absent heart-rate data, or implausibly high or low sleep durations deserve troubleshooting. Restart the device only when ordinary tracking or syncing is failing.
A systematic increase in awake time across otherwise normal nights is consistent with the stated algorithm change. Entirely missing nights, repeated data gaps, or a device that stops recording heart rate point more strongly to fit, charging, syncing, firmware, or hardware trouble.
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If you enrolled in Public Preview and prefer production software, you can consider leaving the preview through the current Google Health or Fitbit account settings. The exact menu path can vary by app version, operating system, account, and region. More importantly, opting out should not be expected to restore the old algorithm or recover original historical scores; no universal rollback switch is established in the available official material.
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Should you buy a different tracker?
A new Fitbit is unlikely to restore the old sleep model. Buy or switch for hardware, comfort, battery life, platform compatibility, or a different ecosystem—not on the assumption that a replacement will recreate earlier scores.
| Option | Best fit | Important trade-off |
|---|---|---|
| Google Fitbit Air | Existing Fitbit users who want a small, screenless sleep and health tracker. | It remains within Google’s changing app and algorithm ecosystem; announced U.S. launch pricing was $99.99, with a $129.99 Special Edition. |
| Fitbit Charge 6 | Users wanting a conventional tracker with a display, sleep stages, Sleep Score, and long battery life. | It uses the same broader Fitbit/Google Health ecosystem. Google lists compatibility with most phones running Android 11 or iOS 16.4 or newer. |
| Oura Ring | People who prioritize sleep and recovery and prefer a ring. | Full daily insights require an Oura Ring and membership, listed at $5.99 monthly or $69.99 annually in the U.S. before tax. |
| Apple Watch | iPhone owners wanting sleep tracking in a full smartwatch. | It is smartwatch-first and not compatible with Android. |
| Garmin | Users focused on sports training, recovery, and battery life. | Its approach is training-first rather than primarily sleep-first. |
| WHOOP | Serious training and recovery users comfortable with a screenless subscription wearable. | It is subscription-centered and has no conventional display. |
Prices and availability can vary by country, promotion, and date. Different brands also use different sensors, algorithms, and score definitions, so a switch will not create a clinically definitive sleep record or make scores directly comparable with Fitbit’s.
When to stop relying on the score
Fitbit sleep tracking is intended for wellness information, not for diagnosing or treating medical conditions. Do not use a reassuring score to rule out sleep apnea, insomnia, narcolepsy, or another disorder.
Ask a medical professional about persistent symptoms such as loud habitual snoring, witnessed breathing pauses, gasping or choking during sleep, severe daytime sleepiness, persistent insomnia, repeated unexplained awakenings, or dangerous drowsiness while driving.
The practical verdict is that Fitbit’s newer sleep tracking can be an improvement in the model while still being disruptive to personal trends. Treat the rollout as a measurement change: compare several nights, look at the component data, preserve records you care about, and investigate genuine gaps separately from lower-looking scores.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
