Eight Sleep Accuracy: Cooling Tested, Tracking Unproven
A mattress cover that heats and cools the bed and tracks sleep without anything worn. The cooling has been through trials; the tracking has not been through any published validation.
Eight Sleep's Pod is two products in one cover: a water-based system that heats and cools each side of the bed, and sensors that record heart rate, breathing and sleep through the night. The two have very different evidence behind them. The current model is the Pod 6; the independent trials below used the Pod 3.
Does Eight Sleep's Cooling Improve Sleep?
People sleeping on it report better sleep in every trial so far. Whether sleep itself changes depends on who ran the study: Eight Sleep's own trial found more deep and REM sleep, while an independent crossover trial found no objective change at all.
What Eight Sleep calls it
Active temperature regulation, with "Autopilot" adjusting each side of the bed through the night. Eight Sleep's own footnotes state that the Pod is not a medical device.
What the trials found
Felt better; mixed objectivelyIndependent, objective measures. In a crossover trial, 34 healthy adults slept on a Pod 3 for 14 nights, with cooling on for 7 and off for 7. They rated their sleep quality and thermal comfort higher with it on, but wrist actigraphy and the Pod's own heart rate, HRV and breathing readings showed no significant difference. The authors note the subjective gains may partly reflect expectancy or placebo. Funded by La Trobe University; the authors declare no conflicts of interest.
Independent, elite athletes. Thirty-two professional Australian Rules football players used either a Pod 3 or their own mattress for 14 nights. The Pod group reported better sleep quality and 29 minutes more self-reported sleep. The authors call for randomized trials with validated objective sleep measures before drawing firmer conclusions. No Eight Sleep-affiliated authors listed.
Eight Sleep's own trial. Fifty-four people wore a home sleep test for eight nights, four with the Pod on and four off. In the first half of the night, men gained 14 minutes of deep sleep and women 9 minutes of REM with cooling on, and sleeping heart rate fell 2 percent while HRV rose 7 percent. The study was funded by Eight Sleep, and its authors include Eight Sleep employees.
Stevenson et al., Clocks & Sleep, 2025 (doi:10.3390/clockssleep7040055) · Stevenson et al., Temperature, 2026 (doi:10.1080/23328940.2026.2703946) · Moyen et al., Bioengineering, 2024 (doi:10.3390/bioengineering11040352 [author affiliations include Eight Sleep; funding listed from Eight Sleep])How Accurate Is Eight Sleep's Sleep and Heart Rate Tracking?
Unknown from published evidence. No peer-reviewed study had validated the Pod's heart rate, HRV, breathing or sleep-stage tracking against a reference as of October 2026. Eight Sleep's accuracy figures come from its own blog.
What Eight Sleep calls it
Eight Sleep describes "clinical-grade sensors" in the cover that track heart rate and HRV, breath rate, snoring and sleep stages with nothing worn. Its science page states heart rate is "99% accurate compared to the gold standard (ECG)" and breathing rate "98% accurate" against respiratory inductance plethysmography, linking both figures to Eight Sleep blog posts rather than to a published study.
What published research found
No published validationThe trials above used the Pod's sensors as a measuring tool rather than testing them. The independent crossover trial recorded heart rate, HRV and breathing with the Pod itself and scored sleep with a separate wrist actigraph, so it says nothing about how close the Pod's own readings are to the truth. Other under-mattress sensors have been tested against sleep labs, and those tend to count sleep well and miss time awake; the under-mattress comparison covers that evidence, which does not transfer to a different product's sensors and algorithm.
Eight Sleep vs Oura: Which Tracks Sleep More Accurately?
On published evidence, Oura. Oura's sleep and overnight heart measurements have been tested against sleep labs and ECG; Eight Sleep's tracking has not been tested, so the two cannot be compared head to head.
What the evidence covers
Oura's sleep tracking was compared with polysomnography in 96 adults aged 20 to 70 (Svensson et al., Sleep Medicine, 2024, three of whose authors report financial support from Oura), and its overnight HRV against a simultaneous ECG, where the Oura Gen 4 reached a concordance of 0.99 (Dial et al., Physiological Reports, 2025). The two products also do different jobs: Eight Sleep's tested claim is about changing the bed's temperature, and Oura's is about measurement. The Oura page has the full evidence.