Smart Bedding® IMU-based contactless monitoring accurately estimated respiratory and heart rates during sleep, achieving overall accuracies of 93.9% and 88.7% using zero-crossing and peak detection respectively, validated against polysomnography as the gold-standard reference.
Key Findings
Results
Respiratory rate estimation achieved an overall accuracy of 93.9% using the zero-crossing method.
Data from 30 participants sleeping on Smart Bedding® while undergoing simultaneous polysomnography were analyzed.
Zero-crossing was compared against peak detection and Burg's method for respiratory rate estimation.
Polysomnography served as the gold-standard reference for validation.
Respiratory rate estimation showed no significant limitations across the frequency spectrum or among sleeping positions.
Results
Heart rate estimation achieved an overall accuracy of 88.7% using the peak detection method.
Heart rate was estimated using zero-crossing, peak detection, and Burg's method for comparison.
Heart rate estimation accuracy decreased when the frequency was below 55 BPM.
Heart rate estimation accuracy also decreased when participants slept in a lateral sleep position, likely due to reduced cardiac signal power.
Validation was conducted against simultaneous polysomnography recordings from 30 participants.
Results
Heart rate estimation accuracy was negatively affected by low heart rate frequencies (below 55 BPM) and lateral sleeping positions.
The decrease in accuracy at heart rates below 55 BPM was identified as a specific limitation of the estimation methodology.
Lateral sleep position was associated with reduced cardiac signal power, contributing to decreased estimation accuracy.
No analogous positional or frequency-based limitations were observed for respiratory rate estimation.
The authors attributed the lateral position effect to reduced cardiac signal power in that orientation.
Background
Smart Bedding® is a flexible bedsheet equipped with a high-resolution sensor network capable of recording movement, pressure, sound, temperature, and humidity throughout the night.
The system uses an IMU (inertial measurement unit) embedded in the bedsheet for cardiorespiratory parameter estimation.
The device is described as a novel, non-invasive, contactless monitoring approach.
Smart Bedding® is positioned as an alternative to traditional polysomnography, which is characterized as accurate but costly, ergonomically limited, and often poorly accepted by patients.
A robust and low-cost preprocessing pipeline was developed for signal processing.
Results
The proposed methodology accurately tracked respiratory and cardiac patterns throughout the night across all sleeping positions for respiratory rate.
Respiratory rate showed no significant limitations across the frequency spectrum or among sleeping positions.
The study involved 30 participants with simultaneous polysomnography as the reference standard.
Three estimation methods were compared: zero-crossing, peak detection, and Burg's method.
The authors conclude that Smart Bedding® is a promising tool for future sleep tracking applications.
What This Means
This research suggests that a specially instrumented bedsheet called Smart Bedding® can accurately monitor breathing rate and heart rate during sleep without any electrodes, straps, or other equipment attached to the body. In a study of 30 people who slept on the Smart Bedding® while simultaneously undergoing standard sleep lab monitoring (polysomnography), the system correctly estimated breathing rate about 94% of the time and heart rate about 89% of the time. The system works by detecting tiny physical movements caused by breathing and heartbeats through sensors embedded in the sheet.
The study found that breathing rate could be reliably measured regardless of what position a person slept in or how fast or slow they were breathing. Heart rate monitoring was somewhat less reliable in two specific situations: when heart rate dropped below 55 beats per minute (a slow heart rate sometimes seen during deep sleep), and when people slept on their side, possibly because the heart's mechanical signal is weaker in that position.
This research matters because standard sleep monitoring (polysomnography) requires a person to be connected to many sensors and wires, which is uncomfortable, expensive, and typically only done in specialized clinics. A contactless system embedded in a bedsheet could make ongoing sleep monitoring more practical and accessible for home use, potentially helping to identify breathing irregularities or other sleep-related health issues without disrupting natural sleep.
Mejía S, Muñoz I, Castaño F, Hernández A. (2026). Non-Invasive Contactless Tracking of Respiratory Rate and Heart Rate During Sleep.. Sensors (Basel, Switzerland). https://doi.org/10.3390/s26041082