The technology behind S+

The S+ works by detecting the movement of your upper body while you sleep. The movement it detects consists of the expansion and relaxation of your chest as you breathe in and out, and overall body movements such as positional changes, arm twitches and shrugs. It includes software algorithms that recognize the combination of respiration and body-movement signals, so that the overall sleep state can be reliably assessed. For example, if you’re moving continuously, you’re less likely to be asleep; conversely, if you’re in deep sleep, there will be relatively little movement and your breathing will be much more regular.

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The Technology of S+ by ResMed
S+ SleepSensor

Technology Found in Nature

The S+ measures movements using ultra low power radio waves (less than 1/10 of Bluetooth®). The basic principle is similar to the echo location system used by bats to hunt insects. The S+ transmits a short pulse of radio waves at 10.5 GHz and then listens for the echo of the pulse. As you move, the phase of the echo changes and is converted into a signal that reflects your movement.

Clothing and blankets are almost transparent to radio waves at the frequencies we use. The echo signal is mostly generated by reflection from your body – as far as radio waves are concerned, you're a large watery object!

Contactless Technology

A major component of the S+ system is our patent-protected SleepSensor that lets it monitor your sleep without actually touching you. No mattress strips. No wristbands. Just a nightstand monitor that can accurately record your breathing and movement. Proprietary software performs a variety of signal analysis tasks including respiration analysis and sleep quality measurement.

The S+ technology’s ability to accurately measure sleep patterns has been published in 10 scientific papers, and has been tested and proven against expert manually scored patient sleep data gathered in several accredited sleep laboratories.

To find out more read our history.

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Note: S+ is not a medical device. If you are seeking information on how to treat a sleep disorder, you should talk to your healthcare provider.