The contenders
Side by side
Buy this if you want sleep data and no fee
Withings Sleep
No subscription7.7/10A 5 mm, 350 g mat under the mattress, mains-powered, with sleep stages, heart rate, respiratory rate, snoring and breathing disturbances. Withings says sleep history and trends are always free.
$199.95Amazon#ad · Price as of November 4, 2026 · How we make money for the link to Withings Sleep
Stock photoBuy this if the bed is too hot
Eight Sleep Pod 6
Membership requiredBrand store only3.7/10A mattress cover that heats and cools each side from 55F to 110F and tracks while it does. The Autopilot plan is in the checkout total at $299/year and keeps billing. Sold by Eight Sleep only, so there is no buy link here.
Sold by Eight Sleep only
Not on Amazon.com. We earn nothing on it, so we don't send you anywhere — Eight Sleep's own page is cited in the sources below.
- Stock photo
The third way, with a catch
Emfit QS
Membership requiredBrand store only4.6/10A ballistocardiography sensor strip with the most serious HRV ambitions of the three. Three years of cloud service are included, then a yearly fee - and without the cloud, Emfit says the sleep features are unavailable.
Sold by Emfit only
Not on Amazon.com. We earn nothing on it, so we don't send you anywhere — Emfit's own page is cited in the sources below.
They solve different problems
The Withings Sleep is a 637 x 190 x 5 mm mat weighing 350 g that slides under the mattress and plugs into the wall. It supports spring, foam and latex mattresses; Withings says it is not intended for water mattresses and that air mattresses may affect accuracy. You install it once and then forget it exists, which is exactly the appeal for anyone who has given up on charging a wearable.
The Eight Sleep Pod 6 is a different category of object. It is a cover that fits over the mattress like a fitted sheet, with a 15.2 lb hub that sits under the bed, pushing water through the cover to hold each side between 55F and 110F. Tracking is included, but the hardware exists to control temperature. Eight Sleep sells it only through its own store and the cart total includes the Autopilot plan, so there is no Amazon listing and no buy link for it on this site.
How each one senses you
Withings is specific about its method: a pneumatic sensor reads heart rate, respiratory rate and movement through the mattress by ballistography, with a separate sound sensor that Withings says “identifies audio signals specific to snoring and breathing disturbances.” That yields sleep cycles, duration, onset and wake time, continuous and average heart rate, snoring episodes and a Sleep Score.
Eight Sleep is not specific. Its product page says “clinical-grade sensors track nightly sleep and health data” and does not name the sensing method. That phrase is doing a lot of work for a device with no published validation behind it, and we label it as a maker's claim wherever it appears on this site. Emfit, for contrast, names ballistocardiography outright and publishes a page explaining it.
Published specs
What happens with two people in the bed
This is the question that decides the purchase for a lot of couples, and the two brands answer it in opposite ways. Withings says the mat “is engineered to focus exclusively on the person resting directly above it” and “does not capture the movements or heart rate of a partner” - one mat, one sleeper, buy a second mat for the other side. Eight Sleep's cover heats and cools for both people and tracks each side separately, with Solo sizes for single sleepers.
If your reason for looking at an under-mattress device in the first place is that one of you refuses to wear anything, that asymmetry matters more than any spec. The wider field, including which devices handle two sleepers, is ranked on best under-mattress sleep trackers.
The cost over three years
| Device | Required plan | Fees, 1 yr | Fees, 3 yrs | Fees, 5 yrs | Device price |
|---|---|---|---|---|---|
| Withings Sleep | No subscription (optional extras) | $0 | $0 | $0 | $199.95 |
| Eight Sleep Pod 6 | $299.00/year | $299.00 | $897.00 | $1,495.00 | Brand store only |
| Emfit QS | $0.00 | $0.00 | $0.00 | Brand store only |
This is the heart of it. Withings requires nothing - the optional Withings+ at $9.95/month or $99.50/year adds a Readiness Indicator and clinical services, not your sleep history. Eight Sleep's Autopilot plan is $299/year, billed annually, and is in the checkout total from day one; Eight Sleep's own page does not say what the Pod still does if the plan lapses, which is an uncomfortable gap for a purchase of that size. Emfit includes three years of cloud service and then charges a yearly fee in euros, and states that without an active subscription the sleep-tracking features are not available.
For a site built around not paying rent on your own data, the ranking writes itself. The full fee picture across every device we cover is on smart ring subscription costs.
Validation, or the lack of it
By comparison, finger-worn rings have been compared with polysomnography repeatedly. If published accuracy is the thing you weigh most heavily, a ring is currently a better-evidenced purchase than any mat - see sleep tracking accuracy and smart ring vs a sleep study.
Which one to buy
Buy the Withings Sleep if you want nightly sleep data with nothing on your body and no recurring bill - it is the only one of the three that asks for no money after purchase. Buy the Eight Sleep Pod 6 only if temperature is the actual problem you are solving and you have accepted an annual plan as part of the deal. Buy the Emfit QS only if deep all-night HRV is the point and the euro-denominated yearly fee after year three is acceptable to you. And if you would rather have the better-validated measurement and do not mind wearing something, look at the sleep-tracking ring roundup instead.
In detail
The contenders, in full
Buy this if you want sleep data and no fee
Withings Sleep
A 5 mm, 350 g mat under the mattress, mains-powered, with sleep stages, heart rate, respiratory rate, snoring and breathing disturbances. Withings says sleep history and trends are always free.
Published specsResearched · every value sourced
How the 7.7 score breaks down
- Cost of ownership (3 years) (30%)
- 9
- Evidence of accuracy (25%)
- 5
- Setup & upkeep (15%)
- 9
- Who it suits (bed, partner, mattress) (10%)
- 7
- Data ownership (10%)
- 8
- Platform support (10%)
- 9
What the specs support
- No required subscription, and Withings says sleep history and trends stay free
- Nothing to wear, nothing to charge: it is mains-powered and 5 mm thick
- Reports breathing disturbances and snoring, which no smart ring microphone can do
- Free unlimited data storage plus Apple Health and Google Health Connect sync
Where it falls short
- Only tracks you in your own bed: no travel, no naps on the sofa, no daytime data
- Needs 2.4 GHz Wi-Fi and a phone for setup; it cannot be installed from a computer
- Not for waterbeds, and air mattresses may affect accuracy
- The Readiness Indicator sits behind the optional Withings+ plan
Skip this if…
…You want daytime activity, workouts or travel nights covered, or you sleep on a waterbed: a mat under your own mattress can do none of that.
#ad · Price as of November 4, 2026 · How we make money for the link to Withings Sleep
Stock photoBuy this if the bed is too hot
Eight Sleep Pod 6
A mattress cover that heats and cools each side from 55F to 110F and tracks while it does. The Autopilot plan is in the checkout total at $299/year and keeps billing. Sold by Eight Sleep only, so there is no buy link here.
Published specsResearched · every value sourced
How the 3.7 score breaks down
- Cost of ownership (3 years) (30%)
- 1
- Evidence of accuracy (25%)
- 2
- Setup & upkeep (15%)
- 5
- Who it suits (bed, partner, mattress) (10%)
- 9
- Data ownership (10%)
- 4
- Platform support (10%)
- 8
What the specs support
- Heats and cools each side of the bed, which no ring or mat does
- Nothing to wear and nothing to charge
- Per-side tracking for two people in one bed
- 5-year warranty and a 30-night trial
Where it falls short
- An annual Autopilot plan is built into the purchase price and keeps billing
- Eight Sleep's page does not say what the Pod still does once the plan lapses
- "Clinical-grade sensors" is a maker's phrase with no published validation behind it
- It is bedroom furniture: a Hub, a water cord and a cover on your mattress
Skip this if…
…You came here to stop paying a monthly fee for your own sleep data: this is the most expensive recurring plan on the site and the Pod's plan-free behavior is not documented.
Sold by Eight Sleep only
Not on Amazon.com. We earn nothing on it, so we don't send you anywhere — Eight Sleep's own page is cited in the sources below.
Stock photoThe third way, with a catch
Emfit QS
A ballistocardiography sensor strip with the most serious HRV ambitions of the three. Three years of cloud service are included, then a yearly fee - and without the cloud, Emfit says the sleep features are unavailable.
Published specsResearched · every value sourced
How the 4.6 score breaks down
- Cost of ownership (3 years) (30%)
- 3
- Evidence of accuracy (25%)
- 3
- Setup & upkeep (15%)
- 6
- Who it suits (bed, partner, mattress) (10%)
- 5
- Data ownership (10%)
- 8
- Platform support (10%)
- 7
What the specs support
- All-night HRV, not a single morning reading, with nothing on your body
- No phone required: the unit uploads on its own over Wi-Fi
- Emfit states the user keeps ownership of their data, and includes a Push API
- The sensor film needs no power of its own and can sit under any mattress
Where it falls short
- The tracking stops without an active cloud subscription: hardware alone is not enough
- Priced in euros and ordered from Finland, with import charges on the buyer
- The ordering page is Finnish-language, and US support is a long way away
- No named validation study, and nothing about how a partner in the bed affects readings
Skip this if…
…You want a device you buy once and own outright: Emfit dropped that model in March 2024, and its sleep tracking now depends on a service you keep renewing.
Sold by Emfit only
Not on Amazon.com. We earn nothing on it, so we don't send you anywhere — Emfit's own page is cited in the sources below.
How we scored this
How these picks were chosen
Every pick here is labeled Researched: chosen from each brand's fee policy, spec sheet, sizing and warranty pages, and the published studies that measured the ring (or its predecessor) against a chest strap, an ECG or a sleep lab, then scored on a public rubric. Every figure links to where it came from, and maker performance numbers are labeled “maker's claim,” so you can see exactly what you're paying for before you buy.
Scores are editorial judgments built from that documented research. Commissions never set a score or decide a pick. The rubric and its weights are published.
What changed
- Published.
Questions
Frequently asked
Does Withings Sleep require a subscription?
Is the Eight Sleep Autopilot plan optional?
Can Withings Sleep track two people?
Which is more accurate, an under-mattress mat or a smart ring?
Receipts
Sources
- Withings US: Sleep under-mattress tracking mat (sensors, metrics, dimensions, power, app, subscription FAQ) (checked 2026-09-26)
- Withings: Withings+ subscription plans and terms (quoted on the Sleep product page) (checked 2026-09-26)
- Withings Health Solutions: Sleep Rx (FDA-cleared, prescription, via healthcare professionals) (checked 2026-09-26)
- Sleep Review: FDA clears under-mattress mat for home sleep apnea screening (Sept 2024) (checked 2026-09-26)
- American Academy of Sleep Medicine: FDA clears Sleep Rx mat for OSA diagnosis (checked 2026-09-26)
- Eight Sleep: Pod 6 product page (price, Autopilot plan, hub specs, sizes) (checked 2026-09-26)
- Emfit Oy: EMFIT QS ordering and pricing page (Finnish; euro pricing, 3-year cloud service then a yearly fee) (checked 2026-09-26)
- Emfit Oy: ballistocardiography, the sensing method behind the QS (checked 2026-09-26)
- Amazon search results for "Withings Sleep tracking mat" (listing titles) (checked 2026-09-26)
Every figure on this page is traceable. Fees come from each brand's own policy pages (with the date we checked), specs from maker pages and listings, and accuracy claims from named, published studies. Hardware prices are set by Amazon and change daily, so we link them live instead of printing them. Read the full method.
