Tommaso De Zan
Mar 26, 2026

Most of the reviews below are rubbish, here is what you need to know: - I have not done any scientific experiment, but the app seems very accurate, more than any other ring/watch out there; - You start receiving useful feedback after the app collects enough data. It took me 55 nights before I started seeing feedback. Sleep2 folks: you said you are working on major updates, including polar loop integration (OMG, exactly the feedback I wanted to send you!)...what else :)? Keep up the great work!

Developer response

Thank you for the great review and your trust in sleep²,Tommaso!We’re happy that you appreciate the app’s precision&the insights into your sleep provide real value.We are continuously working on new features/improvements and we're glad to have you with us on this journey:)Thanks for being part of the sleep²community and for sharing your experience

Lukas Thürmer
Nov 25, 2025

Pretty Good in accuracy and short sleeptips- nettes design.

Developer response

Hello Lukas, thank you so much for your positive feedback! We’re glad to hear that you appreciate the accuracy of our sleep analysis and enjoy the short sleep tips as well as the app design. We hope sleep² continues to support you in better understanding and improving your sleep :)

Damjan Perenic
Nov 8, 2025

Sleep2 is the first app where my sleep data truly matches how I feel in the morning. I still track my sleep with both a sport watch and Sleep2 using a Polar HR sensor, and when results differ, Sleep2 is always closer to my feeling. The detailed analysis, proven accuracy, and clear insights let me see how habits like alcohol affect my sleep. It’s not abstract theory, it’s my nights, my habits, and my metrics showing me the consequences. That makes the advice far more powerful and actionable.

Developer response

Thank you for your outstanding review, Damjan:)We’re delighted that sleep² reflects your actual sleep experience so accurately and that our HR-based analysis with the Polar sensor provides insights you can truly relate to.That's what we aim for-translating scientifically validated data into personally meaningful feedback that helps improve sleep:)

Kamonwan Sooksrikasem
Oct 20, 2025

I'm impressed with the program's design—easy to read, visually comfortable, and highly accurate. I've used it for a week with Polar Verity Sense, and it's excellent at tracking sleep. I'm confident using it for my mother with dementia to monitor sleep for medication management. The staff is also very responsive, helpful, and provides clear information. I truly appreciate it and I’m very happy to have had such a wonderful service experience with the staff team.

Developer response

Thank you sincerely for your review:)We’re very pleased that sleep² provides clear and reliable insights into your sleep using the Polar Verity Sense. It’s wonderful to know that our solution also helps you support your mother’s sleep. We greatly appreciate your recognition of our team’s responsiveness and commitment to clarity and care. Thank YOU!

Nathan Wiltshire
Oct 17, 2025

The app is great. It's accurate, has a clean UI, and doesn't feel bloaty like others. What really impressed me was the support I received from Theresa. My new phone and the Polar H10 were giving me connection issues with the app. Theresa emailed me back and forth constantly over a few weeks to get it sorted. It ended up being a known issue on Polar's end, and the Sleep2 team took it upon themselves to compensate me by sending me a complimentary Polar Verity Sense to use instead. Thanks Theresa!

Developer response

Thank you so much for your amazing review, Nathan! We’re truly happy to hear that you’ve had such a positive experience with both - the app and our support! We appreciate your patience and are pleased we could offer a good solution. We're happy that you are part of the sleep² community:)

Jed Reed
Aug 17, 2025

decent price. very accurate. good format and comfortable to use

Developer response

Thank you so much for the great review, Jed! We're really happy to hear that you appreciate the accuracy, pricing, and overall usability of Sleep². It means a lot to us – thanks for being part of the sleep² community :)

Shub Ware
Aug 1, 2025

amazing app with polar H10. sleep diary makes it all the more like an experimental lab.

Developer response

THANK YOU so much for the 5 stars! It’s great to hear that you're enjoying Sleep² with the Polar H10 and that you recognize how close it comes to a real sleep lab experience. That’s exactly what we’re aiming for :)

Fakey McGee
Jun 29, 2025

Such a well-designed and powerfully helpful app! When paired with one of the recommended devices it also provides one of the most accurate consumer-device data on the market.

Developer response

Thank you so much for your kind feedback, Fakey McGee! We're truly grateful that you value the combination of thoughtful design and scientific accuracy — especially that you recognize the level of precision sleep² offers compared to other options on the market. Thank you for being part of the Sleep² community :)

Anthony Hebert
Jun 20, 2025

Extremely usefull. Finally after trying many other much more expensive options,I found the perfect sleep tracker .It is the closest product on the market to the gold standard of sleep testing/sleep clinic/hospital test. Sleep2 combined w/ Polar Verity Sense has been proven (by the Quantum Scientist ) against very expensive eeg machines and nearly every other consumer sleep tracker product on the market ,and it shown / unbiased to be the best. Thank you Nukkuua & Polar .Sincerely Anthony Hebert

Developer response

Thank you so much for your amazing review, Anthony – we’re truly grateful for your kind words and support! It means a lot to us that you’ve found value in Sleep² after trying so many other solutions and we deeply appreciate your recognition of the scientific quality behind our approach. Thank you for being part of the Sleep² community :)

Emanuele De Gasperis
Jun 12, 2025

Great app. The algorithm seems reliable, however sometimes the data from some nights is lost irremediably for unknown reason...

Developer response

Hello Emanuele, thank you so much for your kind words and the great feedback :) We're glad to hear you trust the algorithm, but we're truly sorry about the occasional data loss-that shouldn't happen. Please feel free to reach out to us at [email protected] so we can look into it together and help prevent it in the future.

Maria VALIANTE
Jun 6, 2025

I really like this app and scan your dreams

Developer response

THANK YOU SO MUCH, Maria :) We're really happy to hear that you enjoy using Sleep²! If you ever have feedback, ideas, or questions - feel free to reach out to us at [email protected].

Daniel Rossbach
Jun 6, 2025

Great interface and presentation of the (seemingly quite accurate) data. Integration with Polar Verity Sense works flawlessly and unobtrusive to wear the entire night. Haven't tried it with the H10 as I find the chest belt uncomfortable to wear over longer periods. Only issue I see is with naps and biphasic sleep not being considered but that is probably by design with this specific algorithm.

Developer response

Hi Daniel,many thanks for your lovely feedback-we truly appreciate it:)We're happy VeritySense integration works smoothly and that you enjoy the interface and data quality.You're right:naps/biphasic sleep aren’t yet fully supported,but good news:we're working on improving that.Thanks for your trust and being part of the community-it means a lot!

Bailey Liipfert III
May 19, 2025

So far, it's working well!

Developer response

Thanks a lot for your 5-star rating:) Great to hear it’s been working well so far - we’re excited to accompany you on your sleep journey! If you ever need anything, just let us know at [email protected]

Brian Rodricks
Mar 27, 2025

Pretty accurate sleep tracking. Highly recommend it

Developer response

Hi Brian! Thank you so much for your kind words and recommendation! We're really glad to hear that you're happy with the accuracy of Sleep². If you ever have questions or suggestions, feel free to reach out via [email protected] - we're always here to help:)

Onuralp çiftçi
Mar 27, 2025

Very accurate and informative works with polar sensor, a bit pricey but it worths if you already have the sensor.

Developer response

Thanks a lot for your review! Great to hear you find the combination with the Polar sensor both accurate and informative. We appreciate your honest comment on the price – and we’re glad you feel it’s worth it :)

Helen Doherty
Mar 23, 2025

love this app

Developer response

Thank you so much - and we love hearing that:) If you ever have feedback, questions or face issues, feel free to reach out via [email protected]!

John R
Mar 9, 2025

Good and accurate sleep tracker

Developer response

Hi John! Thank you for your kind feedback :) We're happy to hear that you're satisfied with the accuracy of Sleep². If you ever have questions, suggestions or issues, feel free to reach out to us at [email protected] – we’re always happy to support!

Alex C
Feb 26, 2025

One of the best apps. Highly recommend. Is developed by actual sleep researchers!!!! Kudos!

Developer response

Thank you so much for your amazing feedback, Alex! We're truly honored – and yes, the app is developed by sleep researchers to ensure scientific accuracy. Your support means a lot to us.

ari budijanto
Feb 21, 2025

Top engga kalah sama sleep trackernya apple watch

Developer response

Dear Ari! Thanks for your feedback. Indeed giving sleep lab data I can tell you that we are not only NOT inferior to apple watch but actually quite a bit better when it comes to sleep staging in the 4 classes: Wake, Light Sleep, Deep Sleep, REM. What you need are sensors specialized just on HRV measurements and being close to the hard & great AI.

Diori Cergy
Feb 20, 2025

I buy Polar H10 and subscribd this app based on the accuracy measured by Quantified Scientist guy. It's nice and motivating to be able seeing the progress you've made to your sleep. The app also informative enough to educate us on how to fix the bad aspect of our sleep. Bryan Johnson also sparked a motivation to fix my terrible sleep. I see immediate results of having higher energy, easy to wake up refreshed naturally, within under a few weeks of sleep earlier & eat further from sleep.

Developer response

Hi Diori! Thanks for your feedback. Indeed tracking with H10 or Verity Sense gives you the best results in terms of tracking accuracy. The "intervention" itself is no rocket-science and we know that. But you know what. It should be "boooooring" and not to exciting because it is all about routines and winding you down in the evening ;-) Sleep² well!

Abhishek
Jan 20, 2025

If you have polar H10 then it's a great app.

Developer response

Danke, das sehen wir bei sleep² auch so ;-)

Krzysztof Dąbrowski
Nov 17, 2024

The app is very intuitive to use and seems more accurate than other sleep trackers.

David Evans
Nov 14, 2024

Good intuitive app so far. I had no idea I was sleeping so badly so it's great to get the insight. Hopefully this app will help me change my bad sleeping habits and improve my sleep function! Con: expensive - I don't see myself using this for more than maybe 4 months as the pricing is too high

Parthapratim Das
Nov 5, 2024

Nice.

Richard Moellers
Nov 1, 2024

Die App hat mir super wichtige Erkenntnisse über meinen Schlaf geliefert und mir Ansatzpunke gegeben, wie ich meine Schlafqualität verbessern kann. Absolute Empfehlung! Wichtig zu wissen ist, dass man für eine verlässliche Schlafanalyse noch einen Pulsmesser zB von Polar Verity Sense braucht. Das Verbinden zwischen Pulsmesser und App funktioniert dann ganz einfach, und schon kann es losgehen.

Lukas
Oct 17, 2024

Sehr schöne App, die Auswertung meiner Schlafdaten gefällt mir.

Developer response

Das freut uns!! Und es kommt noch mehr. Demnächst werden wir auch alle Schlaffaktoren die du auswählst gut aufbereitet zurück melden sodass du weißt wie sich ein bestimmter Faktor auf deine Schlaf- und Herzdaten auswirkt. Stay tuned!

Alex Sepulveda
Sep 14, 2024

Excellent app.

Developer response

Thank you so much for your positive feedback! We're glad you're enjoying sleep² and are happy to be a part of your personal journey to healthier sleep.

Željko Zlatković
Jul 29, 2024

Great app for sleep tracking. Would like to see more devices that can work together with the app. Preferably huawei watches.

Developer response

Dear Zelijko! We took your advise very serious and recently released the ENGLISH version of the app. Sleep² now also comes with new features and you even can use your habitual smartwatch or sleep sensor with sleep² (if it shares its sleep data with GoogleFit). Please thus test and RATE US again. We are sure we are a few steps further by now.

Ahmed Hendy
Jun 9, 2024

Best app to track your sleep, forget about all android watches really useless, use this app with Polar sensor to get such high accurate reading for your sleep phases. Can't recommend it enough. Please keep it up and waiting to add more features to the free version, the current is good but I have high hopes. Thanks guys for this rewarding app

Developer response

Vielen Dank für die positive Rückmeldung! Es wird bald weitere spannende Entwicklungen in der App geben. Stay tuned! Und ja, die Schlaf-Messung macht uns besonders stolz und ist die einzige die tatsächlich an die Genauigkeit in einem Schlaflabor heran kommt und in den 4 Klassen (Wach, Leichtschlaf, Tiefschlaf, Traumschlaf) klassifizieren kann.

Michael Valagio
Jun 7, 2024

Will give this 5 stars due to The Quantified Scientist recommendations. Will update rating based on personal experience. Currently trying this on the Basic Plan and compare with my other sleep trackers. Should have offered some of premium trial at least

Developer response

Many thanks for your great review, Michael! We hope you like the app too:) With the BASIC version you can get to know the app and receive feedback on the most important sleep parameters. If you would like to try out the more detailed sleep analysis for your comparisons, you can upgrade to monthly Pro or have a look at our sleep training.

Frederik A
Jun 4, 2024

Now that the English version is finally out, I decided to subscribe. I really like the accurate results that I get with this using the Polar H10! It is actually very comfortable, and is a really cheap device which I can also use for activity tracking. It would be awesome if you could give us more insights into both our HRV, and the different stages. More details when pressing "sleep phases". Also, would be nice if you could switch the entire statistics tab to another day. Not just the latest day

Developer response

Hi Frederik! We have an update of specific interest to you. **From today you also see your heart rate and heart rate variability (HRV) in the App night by night indicating your recovery potential! ** Please CHECK IT OUT!!

Mateusz Górecki
May 30, 2024

Amazing app and amazing customer service. Now that they added English, the app is a legend. I like it so much that I'm writing this another 5 star review from my second account!

Developer response

THANK YOU, Mateusz for your positive review! We appreciate that you contacted us per mail and would like to thank you for the good communication, which helps us to continuously improve the app. Hope you'll have a good time with sleep2 for a long time to come :)

Alessandro Manfucci
May 11, 2024

Please add english language. Usable in german.

Developer response

Dear Alessandro, the English Version is online! Hope it meets your expectations! We constantly develop new features, so stay tuned and wait for our major updates in August.

Pavlos Topalidis
Apr 8, 2024

I like the latest update that you can include age and gender!

Developer response

Vielen Dank, Pavlos:) Jetzt sind deine Schlafstatistiken noch mehr auf dich zugeschnitten - Wir freuen uns, dass dir diese neue Funktion gefällt!

Jonah Klarke
Apr 3, 2024

I used the app in the free mode, and it really helped me understand how my sleep changes in relation to what life throws at me. I've learnt to anticipate how my sleep will be on a given day given what is happening, and what I can do to sleep deeper and longer. For me, the solutions that worked usually relate to physical activity and nutrition, and timing those things well. Bummer that it's only in German, but since I speak German, I had no problem with that :)

Developer response

Thanks for your positive feedback, Jonah! It's great to read that you can benefit so much from sleep² and how you appreciate the whole content. Good news for you: We are already working on the translation and are looking forward to publish the englisch version in mid-2024.

T ali
Dec 11, 2023

For those really concern about their sleep show details accurate sleep stages when camper to psg and dreem two band who can actually record brain wave and personal sleep coach unlike others one fits all Great app bit expensive and you will have to connect to heart rate monitor you can use polar H10 chest wrap or p90 tracker app is available in only German yet English version will be available by spring 2024. Must try once sleep contributes to all you lifestyle and health don't Ignore it!

CrO2Cl2
Apr 13, 2023

Just met the guy who made it, I have to say, the UX and the UI is real good

Developer response

Thanks a lot for your positive feedback:) It's great that you like Nukkuaa's interface and our tools for a better sleep!

Andreas Puttinger
Jan 25, 2023

Toll!

Chris Gabler
Aug 19, 2022

Extremly accurate sleep phase tracking. The video and audio trainings are very informative and not too long. 5 Stars!