The Oura Ring 5 is our pick for tracking sleep without a watch: it is 2.28 mm thick, and earlier Oura rings have independent validation, including a meta-analysis. The Eight Sleep Pod 6 tracks from the mattress, so you wear nothing, and it also cools or warms each side of the bed.
Updated October 7, 2026.
1. Oura
$399 Silver or Black; plus Oura Membership at $5.99 a month or $69.99 a year
Oura lists Ring 5 at 2.28 mm thick and from 2 grams, and an independent 2025 study of 536 nights found Oura Gen 4 matched ECG for overnight HRV with 0.99 concordance.
2. Eight Sleep
$2,899 Queen; plus required Autopilot for the first 12 months at $199 to $399 a year
The Pod 6 tracks sleep from a mattress cover with nothing to wear, and adds two-zone cooling from 55°F to 110°F, per Eight Sleep; it costs $2,899 for a queen plus a required first-year plan.
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For overnight heart data, a ring can match or beat wrist devices. In an independent 2025 study of 536 nights against ECG, Oura Gen 4 read overnight HRV with 5.96% error, the closest of five wearables tested, while WHOOP 4.0 had 8.17% error.
Some do. The Oura Ring 5 costs $399 but needs Oura Membership at $5.99 a month or $69.99 a year for full insights, and the Eight Sleep Pod 6 needs its Autopilot plan for the first year. The Withings ScanWatch 2 keeps core sleep tracking free, with Withings+ optional at $9.95 a month.