The Eight mattress will measure sleep stages without you having to wear anything.

My experience with them is mixed. I’ve had a couple of theirs and they’ve been markedly inaccurate in some categories. For example, reporting I was not in bed when I actually was, or vice verse on other nights. As a result, the sleep hours were off. I still love it for the temperature control (set to manual, not their ‘auto’ algorithms), but if it can’t reliably report something as simple as whether I’m in or out of bed, then accurately judging sleep stages should be even less likely.

My oura ring has been far more helpful in identifying patterns leading to less quality sleep. For example , by highlighting elevated resting heart rates and asking me if I ate later that night, consumed spicy foods or alcohol, etc. That said, it’s not terribly durable. After a couple years it refused to accept firmware updates. Then a few weeks ago (after maybe 3 years of use) it stopped connecting to the app altogether and support tickets are going unanswered. This is greatly disappointing but I may spring for a replacement anyway because of how helpful it’s been in correlating lifestyle choices to sleep parameters (& quite consistently so).

Agreed on preferring my oura vs my eight bed for sleep tracking. Just found out that their web interface gives you a lot more analytic tools than the app, check that out if you have not already.

Before Apple bought them and discontinued the product last year, the Beddit sleep monitor was the best option for me. I’ve had mine for years and use it religiously. It’s a small sensor that goes on your mattress. You may be able to find one still for sale. It’s far more practical than wearing an Apple Watch to bed.

I have not personally tried it but I have heard good things about this: https://www.withings.com/dk/en/sleep-analyzer