If you have any of a variety of “smart beds,” mattress pads or sleep apps, it knows when you go to sleep. It knows when you toss and turn. It may even be able to tell when you’re having sex, reports Kaiser Health News.

Consumer privacy advocates are increasingly raising concerns about the fate of personal health information — which is potentially valuable to companies that collect and sell it — gathered through a growing number of internet-connected devices.

“We don’t know what happens to all that data,” said Burcu Kilic, director of the digital rights program at Public Citizen, an advocacy group in Washington, D.C.

The information “is also relevant and important to pharmaceutical companies and those that make hospital-related technology,” Kilic said.

Nonetheless, consumers are flocking to mattresses and under-mattress sensors aimed at quantifying sleep as well as sleep-tracking devices; sleep apps are among the most popular downloads on Apple and Android smartphones.