The Oura Ring ($299) has helped me track my sleep quality and provides daily insights so I can take action if I'm not well rested. It not only measure my heart rate variability (HRV) but it also provides a personalized score for my readiness and sleep. On days where I have a low sleep score, it would sometimes recommend I take a quick nap, after which, I'd see an increase in my score (as well as an improvement in how I was feeling.)
The insights provided by this smart ring have also helped me to form better habits to improve my sleep. One night when I had a later than normal dinner, my heart rate lowered later into my sleep and and my Oura ring asked if I had a late dinner that caused my metabolism to work overtime. I have no idea how it knew but it definitely encouraged me to meals at an earlier and more consistent time. Through using this tracker, it has helped me to be more aware of what affects my sleep and how to keep a consistent slumber schedule.