Yes, this exactly. My health is nobody's business but mine and my doctor's.

I'll make a partial exception for the ongoing pandemic, but that's because the disease can be spread to others by close contact. Insomnia, although quite serious, is not contagious.

Overall I don't welcome any attempts by my employer to track anything other than my actual work performance.

Yeah if a tech company starts asking employees to wear Oura ring to track their sleep, that's really out of line. However, a sports or research organization is a different story.