Disclaimer

Last updated: April 11, 2026

1. AI-built content

Every page of CircaTest, including reviews, comparisons, guides, summaries, and the research index, is generated by artificial intelligence. There are no human reviewers wearing devices, no in-house lab, no first-person testing, and no hands-on product experience represented anywhere on this site.

Large language models are known to produce plausible-sounding statements that are wrong, to misattribute citations, to confuse one device generation with another, to mix up units (for example, percent agreement vs. Cohen's kappa), and to hallucinate numbers that look authoritative but are not. CircaTest tries to minimize these failure modes but cannot eliminate them. If a number, citation, FDA clearance, or feature claim on this site matters to a decision you are about to make, open the linked source and confirm it yourself.

2. No first-person testing

CircaTest does not own the devices it discusses. CircaTest has not worn them, clipped them on, paired them with a phone, or run them against polysomnography in a sleep lab. There is no "our testing," no "we wore this for thirty nights," no "in our experience." Anywhere the site appears to be describing direct experience, that wording is wrong and should be reported.

When CircaTest cites accuracy figures, those figures come from peer-reviewed validation studies (for example, Schyvens et al. 2025, Altini & Kinnunen 2021, Miller et al. 2020, Haghayegh et al. 2019), from manufacturer-published white papers, or from FDA submissions. The original authors of those studies did the testing. CircaTest is summarizing their work, not reproducing it.

3. Not medical advice

Nothing on CircaTest is medical advice, a medical diagnosis, a medical opinion, or a substitute for any of those. Consumer wearable devices that hold FDA clearances (for example, FDA 510(k) ECG clearances, or the Apple Watch sleep apnea notification De Novo) are cleared for screening or notification, not for diagnosis. A wearable that flags an abnormal heart rhythm, an oxygen desaturation, an apnea event, or a sleep stage pattern is not making a clinical determination, and neither is CircaTest when it summarizes that wearable.

If you have concerns about your sleep, your breathing, your heart rhythm, your mental health, or any other aspect of your physical or psychological health, talk to a qualified healthcare provider. Do not delay seeking care, do not stop taking prescribed treatment, and do not change a treatment plan because of anything on this site.

4. Accuracy and unit caveats

Validation studies for consumer sleep trackers do not all use the same metric. Different studies report different combinations of: epoch-by-epoch percent agreement with polysomnography, Cohen's kappa (a chance-corrected agreement coefficient), stage-specific sensitivity and specificity, total sleep time bias, sleep efficiency bias, wake-after-sleep-onset error, REM-stage agreement, and four-stage versus three-stage classification. These are not interchangeable. A device with a high percent-agreement number is not necessarily more accurate than a device with a lower kappa, and the same device can look very different across two studies that used different reference standards.

Where CircaTest places multiple devices side by side, it groups them by metric and by source study, and notes when values cannot be compared. If you see a chart on this site that appears to compare two devices on different metrics as if they were the same number, that chart has a bug and should be reported.

5. Specifications, prices, and availability

Hardware specifications (battery life, weight, water resistance), prices, app compatibility, subscription costs, and product availability change without notice. CircaTest pulls these from manufacturer pages, retailer pages, and public records, but they are static snapshots. The number you see on this site may not be the number on the manufacturer's page today. Always confirm price, current model number, and feature availability at the seller before buying.

6. FDA clearances and regulatory claims

FDA clearance numbers cited on CircaTest are taken from the publicly searchable 510(k) and De Novo databases at accessdata.fda.gov. Where CircaTest cites a specific clearance number, that number is real and the clearance exists, but FDA clearance does not equal FDA approval, does not equal a diagnostic claim, and does not equal a guarantee of accuracy in any individual user. Read the clearance summary at the FDA database before drawing any conclusion about what a device is authorized to do.

7. Third-party content and trademarks

Product names, brand names, logos, model numbers, and images referenced on CircaTest are the property of their respective owners. CircaTest is not affiliated with, sponsored by, endorsed by, or partnered with any device manufacturer, and references to products or studies do not imply any such relationship.

8. Affiliate links

CircaTest contains affiliate links and may earn a commission when a reader buys a product through one of those links, at no extra cost to the reader. Affiliate relationships do not influence which studies are summarized, which devices are covered, how a metric is reported, or which device wins a comparison. See our Affiliate Disclosure for the full statement.

9. No warranty, no liability

CircaTest is provided on an as-is and as-available basis, with no warranty of any kind, express or implied, including but not limited to fitness for a particular purpose, accuracy, completeness, currentness, non-infringement, or merchantability. To the maximum extent permitted by applicable law, neither the operators of CircaTest nor any contributor to it shall be liable for any direct, indirect, incidental, consequential, special, or exemplary damages, including but not limited to damages arising from purchasing decisions, treatment decisions, lost data, lost profits, or any reliance placed on the content of this site.

10. Reporting an error

If you find a number, citation, claim, or statement on CircaTest that you believe is wrong, please email hello@circatest.com with the URL and a brief description of the problem. CircaTest takes corrections seriously and will update or remove inaccurate content as quickly as possible.

See also: About CircaTest, Terms of Use, Privacy Policy, Affiliate Disclosure.