Researchers at MIT have developed a new wireless and private way to monitor a person’s sleeping position. The system can use reflected radio signals from a small device on a bedroom wall to determine whether the person is sleeping on their back, stomach or side. The device developed by the researchers is called the BodyCompass.
BodyCompass is the first high-frequency home system that provides accurate sleep data without the need for cameras in the room or body-mounted sensors. Researchers say they believe sleeping posture may be another effective 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 especially important for users with epilepsy. Scientists note that sleeping in the stomach increases the risk of sudden death in people with epilepsy, and the sleeping posture could be used to measure the progression of Parkinson̵
BodyCompass analyzes the reflection of radio signals when they bounce off objects in a room, including the human body. The device is similar to a WiFi router mounted on the wall of the bedroom and can send and collect the radio signals when they return from multiple paths. The researchers can map the paths of the signals working backwards from the reflections to determine the position of the body.
One challenge that scientists had to solve was determining which signals were bouncing off the sleeper’s body instead of bouncing off the mattress or bedside table. Researchers knew from previous experiments that deciphering breathing patterns from radio signals could solve the problem. Signals bouncing off a person’s chest and abdomen are uniquely modulated by breathing and have been used as a marker to determine the reflections coming from the body. BodyCompass predicts correct posture in 94 percent of cases.