sleep² sleeptracker & analysis

My only remaining sleep tracker I signed up for Sleep2 more than a year ago after reading their initial validation study. I work in health research, and we use Polars for data collection, so decided to try the app out. While it's not perfect, it's the best sleep tracker I have tried, mostly because I believe the data in their study, and virtually all other sleep trackers are very inaccurate. Literally, if you need better than 60% accuracy at a sleep stage level, there are no other consumer options. I would love to see additional validation data, but really they're the only option short of semi-clinical hardware. I wore it while at a professional sleep study, as well. One night of data is insignificant compared to the number in their studies, but the data aligned quite well with the lab equipment. I also wore a Withings tracker, and that was quite poor. I wish it had data export. This is my one big request. Sleep2 has been helpful and responsive via email, sending me my sleep data periodically by email, but it's cumbersome. I have a few additional tweaks in the UI that I'd love to see, but they are minor, and even with the export I believe I've found a way around this via Healthkit. The review right before this, with one star, is incorrect. After switching to the Polar Varity, the app has been rock solid. It does not drop your data easily. I use it nightly and have lost maybe two or three nights of data in the last year or two, max. It's a four star app in terms of design - good but with improvements - but it's five stars because I honestly believe it's the only meaningful consumer tracking app there is. That's much more important to me than UI placement.

Will Not Connect Trying to connect with the Polar H10 is impossible even though my phone is connected and other apps don’t have issues connecting. Waste of time!

Connection issues Could be a good app but I wouldn’t know. Connects to my polar H10 at night and I start sleep then when I wake up it can’t end my sleep or connect to my strap. Makes you delete the data.

Accurate stats Sleep stats

Falsely Advertised Paid for the PRO subscription, but it didn’t contain all of the metrics described. Additionally, the UI is quite poor for comparing data between nights and zooming into specific nightly data. And the final nail in the coffin resulting in cancelling subscription in under a week is no error detection or restart capabilities. I had nights where the device I wore (Polar H10) had a brief (5 second) Bluetooth signal loss, due to rolling onto my stomach while asleep. This resulted in Sleep2 ceasing all recording activity and dumping the ENTIRE night’s data.

1 people found this helpful

Good But Needs Improvement This app, when paired with the Polar Verity Sense or Polar H10, provides what may be the most accurate consumer sleep tracking available. According to The Quantified Scientist on YouTube, the data quality is among the best — and from my experience, I trust the metrics it provides. That said, the app experience itself holds it back. First, as others have mentioned, the app occasionally freezes or fails to process the night’s recording — resulting in a complete loss of data. I’ve tried returning to the app multiple times over the past year hoping this issue had been resolved, but it still occurs. Losing an entire night of data is frustrating, especially when accuracy is the main reason for using it. Second, the interface feels dated. It’s functional, but visually it looks retro — almost like something from the 1970s. A modern redesign would go a long way in improving the overall experience. Third, the subscription price (around $19.99/month) feels steep given the stability issues. For an app at this price point, seamless data transfer and reliability should be expected. Finally, it would be extremely helpful to allow multiple sleep sessions per calendar day. For those of us with fragmented sleep or irregular schedules, the current limitation makes tracking less practical. In short, the sensor + app combination offers superior data compared to most other trackers. However, without consistent reliability and smoother usability, it’s fair to question whether it justifies the monthly subscription cost.

Great insight Everything works well. Heart rate tracking is clearly the best. Sense I’m using the polar h10. I don’t have a way to test the accuracy. However it does seem to be more accurate than my Apple Watch SE 2nd gen.

Very expensive and terrible with connecting to H10 Polar strap It always gives me problems when connecting to the polar H 10 strap. The stress of always trying the different ways of resetting and repairing probably throws off the HRV readings anyway. And it’s extremely overpriced. You probably would have a lot more people willing to pay if you lowered the price. Your profit would increase by more customers. I would expect seamless connections with my Bluetooth device as well.

Room for improvement When it works it works well but the app itself is pretty buggy. It is prone to getting hung perpetually on loading screens then dropping your data for the night when you try to reopen the app which is incredibly frustrating. Wish they would focus on a higher quality of code.