You need at least an EEG to have even a remote chance of getting good data. No smartwatches or rings will do the trick. Zeo was a good one, but discontinued 10

You need at least an EEG to have even a remote chance of getting good data. No smartwatches or rings will do the trick. Zeo was a good one, but discontinued 10 years back. https://www.semanticscholar.org/paper/Consumer-Sleep-Tracking-Devices%3A-A-Critical-Review-Lee-Finkelstein/a18d14fbc724c2dfe982fa4b44fbae1d5948c68b?p2df https://www.semanticscholar.org/paper/Consumer-Sleep-Trackin...