Researchers at MIT have developed a new wireless and private way to monitor a person’s sleep position. The system can determine if the person is sleeping on their back, stomach, or side using reflected radio signals from a small device mounted on a bedroom wall. The device the researchers created is called BodyCompass.
BodyCompass is the first home-ready, radio-frequency-based system that can provide accurate sleep data without requiring cameras in the room or sensors attached to the body. Researchers say that they believe sleep posture can be another impactful application of their system. Similar wireless sensing systems have been used by researchers in the past to study sleep stages and insomnia.
The system is particularly important for users with epilepsy. Scientists note that stomach sleeping increases the risk of sudden death in people with epilepsy and sleep posture could be used to measure Parkinson’s disease progression. Diseases like Parkinson’s prevent a person from being able to turn over in bed. MIT’s researchers also note that the system could be used to monitor infant sleeping.
BodyCompass works by analyzing the reflection of radio signals as they bounce off objects in a room, including the human body. The device looks similar to a Wi-Fi router attached to the bedroom wall and can send and collect the radio signals as they return from multiple paths. Researchers can map the paths of the signals working backward from the reflections to determine the body’s position.
One challenge scientists had to solve was how to determine which signals were bouncing off the sleeper’s body rather than bouncing off the mattress or nightstand. Researchers knew from previous experiments that deciphering breathing patterns from radio signals could solve the problem. Signals that bounce off a person’s chest and belly are uniquely modulated by breathing and were used as a tag to determine reflections coming from the body. BodyCompass predicts the correct body posture 94 percent of the time.