I fail to see the problem. You got 8 to 10 hours every night didn't you?
Could info from an Apple Watch or any sleep tracker be used in a prosecution?
If you're stupid enough to wear one and let it dump your private info into the cloud (read data centre), I am sure it could. The incessant drive for personal information is driven by those stupid enough to hand it out. Loyalty cards, rewards cards, apps that track every move, apps that dump your health info into a data centre, all of it, most folk fail to see any problem and actually love this stuff. Sheeple indeed :-)