Apple Beddit 3

The Beddit 3 sleep tracker automatically tracks your sleep to help you achieve better sleep. Beddit is completely ambient, so there's no need to wear or charge it. The thin, flexible, and soft sensor is unnoticeable when placed under the sheet on top of the mattress. It senses and automatically begins tracking, when you lie down on the bed - collecting and analyzing sleep-related data, such as sleep time and efficiency, heart rate, respiration, temperature, movement, snoring, room temperature, and room humidity.