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- Individuals (B2C)
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- Insurance providers and research & medical institutions
How sleep² Turns Polar Heart Rate Data into Lab-Validated Sleep Analysis
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Best in class sleep staging
Combining Polar’s high quality heart data with sleep²’s AI algorithm.
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From data to real improvement
Understand your sleep and receive personalized recommendations to improve it over time.
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See what really affects your sleep
Identify patterns, habits and behaviors that influence your sleep quality.
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More than tracking
Coaching, routines and scientifically grounded tools including sleep exercises to actively improve your sleep.
Overview
By partnering with Polar, sleep² closes the credibility gap in at-home sleep measurement — turning Polar's high-quality heart-rate signal into objective, scalable sleep analysis outside traditional sleep labs – validated against polysomnography.
The sleep² platform is positioned as a “virtual sleep laboratory at home”, translating academic sleep research into practical, everyday tools.
sleep² works across multiple use cases:
- Consumers seeking better sleep and recovery
- Businesses and insurers offering preventive health and wellbeing programs
- Elite sports and safety‑critical professions (e.g. athletes, emergency responders)
- Research and medical settings, where laboratory‑quality sleep data is required
The Company
sleep² focuses on objective sleep analysis and evidence‑based sleep improvement, combining a mobile app that tracks sleep using heart‑rate variability (HRV) data, sleep diaries, and imported data from devices such as Apple Health, Google Health, and Polar sensors.
sleep² offers personalized sleep coaching and training, including a 12-week Intensive Programme based on Cognitive Behavioral Therapy for Insomnia (CBT-I), which is CE-certified as a medical device in the EU for people with insomnia.
The Challenge
The core problem: Unreliable sleep measurement outside the lab. Most consumer sleep apps rely on movement-based tracking (actigraphy) from smartwatches or phones. These methods are convenient but some can struggle to accurately detect sleep stages, awakenings, and sleep quality, especially for people with insomnia or fragmented sleep.
sleep²’s challenge was therefore: How to deliver objective, validated sleep measurement at home, without the cost, waiting time or complexity of a clinical sleep lab.
The Solution
Why Polar is critical to solving this
Polar’s H10 chest strap and Verity Sense optical sensor provide high quality heart rate and heart rate variability (HRV) data, which is strongly correlated with sleep stages, autonomic nervous system activity, and sleep disruption.
sleep²'s algorithms are designed for exactly this kind of high-resolution heart-rate and HRV data:
- Accurate detection of sleep depth, awakenings, and recovery
- Reliable measurement in people who don’t move much but are still awake
"Evidence-based sleep therapy is only as good as the data behind it. sleep² is currently the only product on the health market that combines high-precision sleep measurement with evidence-based therapy — built on more than 20 years of sleep research at the University of Salzburg. What we value most about Polar is the quality of their HR and HRV signal and the openness to share raw data. That signal quality is the foundation our best-in-class AI needs to reach 95% accuracy in sleep staging compared to the gold standard. Together, we pair best-in-class measurement with a science-backed digital coach: a rare combination, and exactly what our users and healthcare partners expect from us." — Dr. Thomas Winkler, CEO of nukkuaa GmbH (sleep²)
Enabling evidence based digital therapy (CBT I)
sleep² offers CBT I based sleep training, including a CE marked digital medical product for insomnia in the EU. CBT-I works with the sleep diary as its core instrument. Adding objective, validated measurement makes progress visible for users and clinicians, supports adherence and allows healthcare partners to evaluate outcomes. The Polar partnership supports this by:
- Providing validated physiological inputs (HRV, heart rate patterns)
- Making therapy progress measurable, transparent, and auditable
- Supporting medical, insurer, and employer use cases
Polar's signal quality is what lets sleep² deliver its full measurement precision at home — which is why Polar sensors are the company’s recommended setup for medical, insurer and employer programs.
For people with sleep disorders:
- Poor sleepers often lie still while awake
- Movement based trackers might misclassify wakefulness as sleep
- Users lose trust when recommendations don’t match how they feel
By integrating Polar sensors, sleep² solves the credibility gap in consumer sleep technology:
- Sleep insights align better with user experience
- Recommendations become more personalized and effective
- Drop off and skepticism are reduced
This is particularly important for insurers, elite sports programs, and safety critical professions where measurement accuracy matters.
Results
In the University of Salzburg comparison study (Topalidis et al., 2025), which covered eight systems, 18 participants, 90 nights of home polysomnography, and over 80,000 scored epochs, sleep² with the Polar Verity Sense reached 83.7% four class sleep staging accuracy and deviated by around 6 minutes on total sleep time.
