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The button may appear grayed out if there is no stable internet connection. Please check whether your smartphone is connected to the internet (e.g., via Wi-Fi or mobile data) and whether the signal is strong enough. Then simply try again.

1.) How to check the battery level: When you tap the “Go to sleep” icon (moon) in the Sleep² app, the Polar sensor will connect, and the battery level will be displayed at the bottom of the screen. 2.) Verity Sense recommendation: Charge briefly every two nights (in the evening or morning). If the battery level is below 50% in the evening, the sleep recording cannot be started. In this case, charging for 10–20 minutes is usually enough for one night. When the LED blinks green, the battery is at around 80%. Note: To switch the sensor on, press the button briefly (the light will turn on). To switch it off, press and hold the button. 3.) H10 sensor recommendation: The replaceable battery lasts for many weeks. The Sleep² app will notify you in time when the battery needs to be replaced. Note: The sensor switches on automatically when in contact with the skin and turns off as soon as the contact ends.

How do I import data from Apple Health or Google Fit? 1.) Open the Sleep² app and go to "More" →"Automatic sleep analysis" → "Apple / Google Health" 2.) Activate the buttons for Apple Health or Health Connect import 3.) You will automatically be redirected to the respective app, where you need to grant sleep² access. 4.) Important: a.) If you are using a smartwatch or other sensors (except Polar Verity Sense / H10), you first need to allow these devices in Apple Health or Health Connect to record and store your sleep data. b.) Every morning, you should first synchronize the data from your external devices with Apple Health or Health Connect, so that sleep² can import them automatically when starting the app c.) In Apple Health, you can define under “Data Sources” which source should be prioritized. d.) Only the data stored in Health will be imported. These data are already pre-processed, meaning the raw data cannot be analyzed by our algorithm. e.) You will get the most detailed and accurate analysis using our Polar sensors together with our scientifically published algorithms. How do I export my sleep² data? If you sleep with a Polar sensor (Verity Sense or H10) and your data are analyzed with our algorithm, you can also export your results back into Apple Health / Google Fit. This allows you to keep all your health data in one place and combine them with other metrics. To activate this function, open the Sleep² app → More → "More" > "Automatic sleep analysis"→ "Data export". Once enabled, your analyzed sleep results will automatically be written into Apple Health / Google Fit after each night.

In the general settings of your smartphone, you can activate the zoom or "magnification gesture" under "Accessibility" or "Input Assistance".

Polar Verity Sense: The VS armband is best worn directly on your upper arm, with the green-light sensor resting on the inside, just under your biceps. Polar H10: The H10 strap should wrap around your chest just below the breast. It should fit snugly, but not uncomfortably tight. The sensor part that contains the battery is ideally placed at the front center of your chest so that it doesn’t press uncomfortably. On the Polar website, you can also find detailed instructions for your Polar Verity Sense armband or your Polar H10 chest strap

With the Sleep² app, you can also carry out your sleep recording entirely without an internet connection. Before tapping “Go to Sleep” in the evening or “Wake up” in the morning, switch on airplane mode (no Wi-Fi, no mobile data) and make sure Bluetooth is enabled. In the morning, the app will display a message that no internet connection is available and ask whether the data should be saved offline – confirm this with “Yes.” As soon as your smartphone is back online, you can go to the corresponding entry in the Diary and select “Analyze sleep data.”

1.) Switch on the sensor! Verity Sense (VS): Press the sensor button briefly (do not select a training mode!). H10: Put on the sensor. 2.) Open the Sleep² app and tap the “Go to Sleep” symbol in the center of the bottom menu bar. 3.) Select “Sleep with sensor.” Follow the on-screen instructions and grant permissions if required. 4.) Start the sleep recording. (You can now sleep in airplane mode if you wish.) 5.) In the morning: Tap “Wake up” to end the recording and start the analysis. Note: Before tapping “Wake up,” make sure Bluetooth is enabled and you have a stable internet connection. If your connection is unstable, it’s better to switch to airplane mode and first read out the data offline (see FAQ Offline Mode). After tapping “Wake up,” Sleep² reconnects to the sensor and retrieves the data stored on it. 6.) Save your sleep diary entry and take a look at your sleep analysis (Home, Statistics, Diary). 7.) You can now switch off your sensor. VS: Long press on the button. H10: Remove the sensor. IMPORTANT: Sleep² manages everything automatically! This means that settings/connections outside of Sleep² are neither necessary nor desired (i.e., no pairing via smartphone Bluetooth settings and no synchronization with the Polar Flow app, including active training modes). It is essential that you let Sleep² handle both the pairing of sensors and the sleep recording. Otherwise, the sensors will be considered “in use,” and Sleep² will no longer be able to access them.

That is exactly one of the strengths of Sleep². As a spin-off from the University of Salzburg, we put scientific validity, continuous research, and ongoing improvements of our sleep training and sleep analysis at the very forefront. We have already investigated and confirmed in several studies that Sleep² improves sleep both subjectively and objectively. For the most recent internationally published study from our team, take a look here, and feel free to read more details under “Research.”

Sleep² works with the Polar Verity Sense armband and the Polar H10 chest strap (soon also with Polar 360 and Polar Loop). You can order both sensors directly through the app under “Settings → Automatic Sleep Tracking → Buy Sensor” with a 10% discount. Alternatively, you can also import sleep data from other wearables into Sleep² via Apple Health or Google Health Connect. Please note, however, that these devices do not provide us with raw data. Only pre-processed data are transferred, which cannot be analyzed with our algorithm.

You can connect your sensor in two ways: a) via “More” → “Automatic Sleep Tracking”, or b) by tapping the round “Go to Sleep” icon in the app. Before each use, please make sure that your sensor is switched on (Verity Sense) or has skin contact (H10), and that Bluetooth is enabled. It is also important not to use the sensor simultaneously with other apps (i.e., do not pair it manually in your smartphone’s settings or with other apps such as the Polar Flow app). For Bluetooth to detect your sensor and establish access, please enable Location Services on your smartphone and approve all pairing requests. Since all data are stored locally on the sensor without any active wireless connections, you can switch your smartphone to airplane mode once the connection has been established in the evening before going to sleep. In the morning, make sure to re-enable all connections (i.e., Bluetooth) before reading out the data.

In the sleep² BASIC program, you can get to know our app for free by receiving feedback on the 3 most important sleep parameters (sleep score, sleep duration, and sleep efficiency) and gaining access to 2 exercises (1 relaxation exercise and 1 video on sleep hygiene). A detailed sleep analysis and a variety of exercises for healthier sleep are only available with an upgrade to PRO or INTENSIVE. With our sleep² PRO program, you can optimize your sleep and go through the day energized: You can document your sleep, receive detailed daily and weekly statistics, as well as evidence-based sleep tips based on them. Based on your sleep data, exercises adapt to your personal needs, and if you measure your sleep objectively, you also receive a sleep hypnogram and your HRV values. All functions of our app are available to you in full as a monthly (€12.99) or annual (€99.99) subscription. Our sleep² INTENSIVE program is for all those who suffer from acute sleep problems and want to regain restful sleep. Here, you can use all the functions of the PRO program, with the ADDITION of a structured program based on cognitive behavioral therapy for insomnia available for €99.99 for 12 weeks. Each week, we recommend that you complete a certain number of tasks to meet the conditions for advancing to the new week. Note: The intensive program is a certified medical product in Europe and is therefore only available in this region.

It is important that you are still wearing the sensor when reading out the data (the H10 switches off as soon as it loses skin contact) or that it is switched on (Verity Sense). If you slept in airplane mode, wait a few seconds until you have a stable internet and Bluetooth connection again (alternative: see FAQ Offline Mode), and only then tap the “Wake up” button. If you continue to experience difficulties, try closing the Sleep² app (“swipe it away”) and restarting it, and also turning the sensor completely off and on again. Don’t worry – your data will not be lost, as they are stored locally on the sensor. It may also help to turn Bluetooth off and on again on your smartphone and move to a place with fewer Bluetooth devices in the area.

In the sleep² BASIC program, you can get to know our app for free. A detailed sleep analysis and exercises for healthier sleep are only available with an upgrade to PRO or INTENSIVE. With our sleep² PRO program, you can optimize your sleep and go through the day full of energy. Based on your sleep data, exercises are tailored to your personal needs. All features of our app are fully available to you with a monthly (€12.99) or yearly (€99.99) subscription option. Our sleep² INTENSIVE program is for those who suffer from acute sleep problems and want to regain restorative sleep. The structured program is based on cognitive behavioral therapy for insomnia and is available to you for €99.99 for 12 weeks. We recommend using sleep² in combination with a Polar bio-data sensor to receive an accurate sleep analysis in addition to sleep training. When purchasing the Polar sensor directly through sleep², you receive a 10% discount (deducted at checkout) and can purchase your Polar sensor at a friendship price: Polar H10 for only €76.42 (instead of €89.90) and Polar Verity Sense for only €84.92 (instead of €99.90). By the way, you can also use this gold standard of heart rate measurement and movement tracking for sports activities. ! Important Note ! A trial version active through the Google Play Store or Apple App Store must be terminated at least 24 hours before the trial version expires to avoid being charged for a subscription. The entire payment process for an APP purchase is handled through your smartphone provider (Apple device: AppStore or Android device: Google Play Store), meaning you have become a contract partner with Apple or Google upon subscription. Therefore, cancellation must also necessarily be done through your Apple or Google account, e.g., via smartphone (Settings>Subscriptions). Unfortunately, unsubscribing or deleting the account within the sleep² app alone is not sufficient here. You should have also received an email notification from Apple or Google regarding the end of the free trial period.

Write us an email at hello@sleep2.com or use the contact form on our homepage www.sleep2.com/contact

In some cases, especially at the beginning, there may be problems pairing the sensor. Please make sure that your sensor is switched on (Verity Sense) or has skin contact (H10), and that Bluetooth is enabled. For Bluetooth to detect your sensor, it may also be necessary to activate Location Services on your smartphone. Please do not connect your Polar sensor directly in your smartphone settings, but only via the Sleep² app. It may also help to deactivate other Bluetooth devices nearby, since multiple Bluetooth signals can sometimes cause connection issues. If your smartphone sends a pairing request, please confirm it once. If problems persist, you can try unpairing the sensor in the Sleep² settings and also deleting/“forgetting” it in your smartphone’s Bluetooth settings. Then attempt to pair again exclusively via the Sleep² app. For the Verity Sense, make sure to switch on the sensor with a single short click (do not select a training mode) and confirm that it is not already in use by another app (e.g., Polar Flow). For the H10 sensor, you can also try removing and reinserting the battery. If this still does not solve the issue, update the sensor’s firmware and/or reset the sensor See also: Polar Support .