MIT Bodycompass can he watches the stops sleeping of people without use camera, using radio signals.
A team of MIT researchers has developed a device that monitors the sleep postures of people with radio frequencies.

It can monitor people's sleep and postures without having to use cameras or sensors on their bodies. It is a wall screen which the group called "BodyCompass" and works by analyzing radio frequencies as they bounce off objects in a room.
According to MIT researchers, a device that can monitor sleep postures has many possible uses. It could be used, for example, to monitor the progression of Parkinson's disease, as people with the condition lose the ability to go back to bed.
To distinguish between radio signals bouncing off a body, and signals bouncing from random objects in a room, the system focuses on bouncing signals from a person's chest and abdomen. In other words, the parts of the body that move during respiration. It then sends these signals to in cloud, so that the BodyCompass system can analyze the user's attitude.
The team trained the device's neural network and tested its accuracy, collecting 200 hours of sleep data from 26 people who had to wear sensors on their chest and abdomen in the beginning. They said that after training the device in data a week, predicted the correct posture 94% of the time.

In the future, BodyCompass could be combined with other devices to push sleeping people to change positions, such as "smart mattresses ». When this happens, the device could alert people with epilepsy if they have taken a potentially fatal sleeping position, reduce the incidence of sleep apnea and alert carers to move immobile patients at risk of developing ulcers. It could also help everyone else sleep well, because surely we all need it.
Shichao Yue will introduce the system at congress UbiComp 2020 on September 15th, but you can read the survey [PDF] on the MIT website.