Can a Radar Sleep Monitor See Through Blankets? What It Senses and What It Doesn't

A duvet hides you from a camera. It does not hide chest motion from a radio. That is the useful fact, and it is also the privacy question. Radar is not a picture. It is still a sensor in the room.

Disclosure: I am Dovy, founder of Komori Care. We are building a contactless bedside sleep monitor, coming 2027, wellness only.

Quick answer

• Research says yes to the bedding part. An IEEE Smart World Congress 2025 paper reports a mmWave system that classifies sleep postures under a blanket, about 95% on six postures in that experiment. An ACM paper detects bed entry, exit and stay from mmWave reflections (median timing errors under a second in the preliminary results).
• Radar measures reflected radio signals, not pictures. Google's Soli sleep paper describes bedside radar sleep sensing without a camera, with on-device processing of the raw sensor data.
• Privacy still depends on the product: ask whether processing is on the device, whether there is a camera or mic, and what leaves the room.
• Komori Care (coming 2027, wellness only): bedside 60GHz radar with no camera; a one-press top button cuts sensing, and core tracking can run offline (some extra features need the cloud).

For DIY boards, see Home Assistant mmWave sleep tracking. For study numbers, see how accurate radar sleep trackers are.

What the papers actually measured

The IEEE work is a lab system for fine-grained posture under a blanket, not a consumer SKU. The ACM work is bed events (in, out, stay), again a research prototype. Neither paper is a rating of Hatch, Sleepal, Nest Hub or Komori.

Google's Nest Hub paper is the consumer-shaped one. Low-energy radar on a nightstand, no camera, no microphone required for sleep-wake. Raw sensor data processed on the device. Only the result (awake or asleep) is uploaded in that description.

Radar is not a camera

A camera makes an image. Radar records how a radio pulse bounced. You cannot hang that bounce on a wall. You can still infer breathing, motion and, in some systems, a coarse posture.

Google's Nest Hub FAQ says Motion Sense does not generate distinguishable images of your body or face. That is Google's wording for that product. Ask each vendor what its sensor outputs.

What to ask before you put one by the bed

• Is processing on the device or in a cloud?
• Is there a camera or a microphone, even as an option?
• What is stored, and for how long?
• Is there a hardware off switch?

Komori Care (coming 2027)

Komori Care uses 60GHz radar above or beside the bed. No camera is required, the optional camera records to an encrypted SD card, cloud is optional, and a one-press button cuts sensing. It is a 2027 wellness product.

FAQ

Does radar see my body? It does not make an image. It reads reflected signals. Google's research page describes bedside radar sleep sensing without a camera.

Can radar work through a duvet? The IEEE paper says posture classification under a blanket, about 95% on six postures in that test. That is a research system, not a store shelf claim.

Is radar the same as a camera? No. One records light. The other records radio reflections. Both can be nosy if the product uploads more than you wanted.

What should I ask a vendor? On-device or cloud, camera or mic, what is stored, how long, and how you turn it off.

Can I switch Komori Care off? Komori Care (coming 2027, wellness only) has a one-press top button that cuts sensing.

Keep reading

• Home Assistant sleep tracking with mmWave
• How accurate are radar sleep trackers?
• Is a radar sleep monitor safe?
• Radar sleep sensing explained
• Sleep monitor without a camera

---

Komori Care is a contactless sleep monitor in development. Camera-free position tracking, coming 2027. Wellness only. Join the waitlist.