Sleep Tracker That Tells Left vs Right Side (2026): What Actually Labels It

Most rings and watches log stages, not which side you slept on. If you want a left-side vs right-side label, you need a sensor on the torso or head, or a contactless system built for that job.

Disclosure: I am Dovy, founder of Komori Care. Contactless bedside radar for sleep position, coming 2027, wellness only, not FDA-cleared. Komori Lite $399, Komori with base $799. One-press top button cuts sensing. Optional camera records to an encrypted SD card.

Quick answer

Pick by how you want the label:

• Ear tag, shipping: Flowtime's Brain Tag logs left side, right side, back, front and upright. You have to tell the app which ear the tag is on (Flowtime help).
• Wear your iPhone, shipping: SomnoPose charts time facing left, right, up and down. The listing says you wear the iPhone or iPod touch. Free, no in-app purchases or subscription (App Store).
• Chest-belt iPhone, shipping: Morfify Sleep uses iPhone motion sensors for Supine, Prone, Left, Right and Upright. Basic is free and tracks position. Premium is an in-app purchase for vibration alerts. iPhone 8 and newer, iOS 16+ (Morfify).
• Contactless research, not a store: MIT's BodyCompass used a wall-mounted wireless device and reflected radio signals. In that 2020 study, 26 people at home produced 200 hours of data. Accuracy was 94 percent with a week of training, 87 percent with one night, and 84 percent with 16 minutes of held postures. It distinguished a sleeper on the right side from a slight right tilt (MIT News).
• Phone-on-chest paper: A 2021 MDPI Sensors paper describes SleepPos, an Android app worn on the sternum. Sleep angle 0° is left, 90° is supine, ±180° is right, −90° is prone (MDPI). Research software. I did not find a current store listing to send you to.
• Contactless, wait: Komori Care, coming 2027. Design intent: label left side vs right side, plus back and stomach. Wellness only.

A wrist ring still does not answer this. See why wearables miss sleep position.

Flowtime Brain Tag

The help page is blunt. The Brain Tag has a 6-axis accelerometer. Positions tracked: left side, right side, back, front, upright. It logs changes through the night. You must select in the app whether the tag is on the left or right ear, or the labels will be wrong.

That is a body-worn tag, not a nightstand.

SomnoPose

The App Store listing (as of October 2026): Sleep Position Monitor. Free. Wear the iPhone in a stable, forward-facing position. It charts time facing left, right, up and down. Optional alarm if you pick a position to avoid. No in-app advertising, purchases or subscription. The listing says it is not intended to diagnose or treat any disease. I am listing it as a position logger, not a treatment.

Morfify Sleep

The app page (as of October 2026): live position tracking with iPhone motion sensors. Labels: Supine, Prone, Left, Right, Upright. Basic is always free and tracks position and position changes. Premium is an in-app purchase and adds vibration when you enter an unwanted position. Compatible with iPhone 8 and newer, iOS 16 or later. Their own copy talks about a chest belt. I am not repeating their airway claims as a recommendation.

What the research actually showed

MIT News (Sept 11, 2020) describes BodyCompass as a small wall-mounted device that infers posture from radio reflections, without cameras or sensors on the body. The published numbers above are from that story. I am not quoting MIT's "home-ready" line. I am not selling BodyCompass. It is a paper and a news story, not a checkout.

The MDPI SleepPos paper is the other citable tracker in this results list. Sternum-mounted Android phone. Angle map for left, supine, right, prone. Also research, not a buy-now SKU I could open.

Komori Care (coming 2027)

Contactless bedside radar. Design intent: a left-side vs right-side label, plus back and stomach, on a position timeline. One-press top button cuts sensing. Optional camera records to an encrypted SD card. Designed local-first with optional cloud sync.

This is not a shipping readout. This page does not assign Komori an FCC ID or an accuracy figure. No claim that it separates two sleepers or handles pets.

Komori Lite $399. Komori with base $799. Coming 2027. Wellness only. Join the waitlist.

Comparison

FAQ

Does Apple Watch tell left side from right side? No. Apple Support lists REM, Core, Deep, wake-ups and a sleep score. Not body position. More: why wearables miss sleep position.

Does Oura tell left from right? No. Oura writes about positions using movement and blood-oxygen data. That is not a left/right readout.

What can I use tonight? Flowtime, SomnoPose or Morfify, per the pages linked above. They all put hardware on you.

Can radar tell left from right without wearing anything? The MIT study did it in research conditions. Komori's design intent is a left-side vs right-side label, coming 2027, wellness only. Not shipping today.

Is this medical advice? No. Wellness reading. If a clinician asked you to sleep on one side, follow that clinician.

Keep reading

• Does Apple Watch or Oura track sleep position?
• How to track sleep position without a camera
• Pregnancy sleep position tracker
• Oura alternative without a wearable
• Is a radar sleep monitor safe?

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Komori Care is a contactless sleep monitor in development — camera-free position tracking, coming 2027. Wellness only, not FDA-cleared. Join the waitlist.