Most affordable yet good watch for sleep?

Dear everyone! I would like to track and optimize my sleep. I am interested in how was my sleep score, do i have something related to sleep apnea etc. I would also like to know how recovered i am, i train nearly every day.

Otherwise, i dont really need the watch for anything else.

Could you please recommed a watch and an app (or both together) for my needs? I am ready to spend some money for my requirements, but not that much as a new apple watch or something.