[Foivos]

Something like this [1] then? I have not used it though, so I do not know how well it works.

https://www.withings.com/no/en/sleep-analyzer

[proamdev123]

Nice device, but the data is stored with them, so the privacy issue remains.

[antiframe]

Maybe, but it looks your data is stored on their servers. I consider data that's not stored on my machine with my encryption key to be essentially public data since any company, even one I trust, can be bought and the terms changed without warning.