Harvard Medical School research uses Cerebra’s Odds Ratio Product (ORP), the first highly validated measure of sleep depth, to predict driving safety in patients suffering from obstructive sleep apnea.


Two research studies demonstrate how Cerebra’s sleep depth measure, Odd Ratio Product (ORP), is enabling new discoveries in sleep, sleep issues, and sleep care. Researchers around the world are using Cerebra ORP to measure sleep depth and gain more insight into brain activity during sleep. Understanding sleep depth is key to understanding sleep quality and the use of ORP is changing the future of sleep diagnosis and therapy.

“While sleep duration and sleep timing are well accepted as important aspects of a healthy sleep and, thus, overall health,” explains Earl Gardiner, CEO Cerebra, “less attention has been paid to another dimension of sleep – sleep depth or quality – largely because until now, there’s been no practical or reliable way to objectively measure this.”

ORP is built on a patented algorithm that micro analyzes the EEG signal providing a continuous measure of sleep depth over the entire night’s sleep. Cited more than 100 times in peer-reviewed sleep research, ORP is the first highly validated measure of sleep depth.

Study confirms Cerebra ORP as a more sensitive and accurate measure of sleep depth, opening up new research into sleep quality as a major factor in sleep health.

Data from 41 healthy subjects who underwent a series of controlled sleep studies compared how delta power and ORP responded to conditions where sleep depth was a factor – including correlation with sleep staging, response to sleep restriction, and relation to an individual’s arousability. The study was conducted by Dr. Magdy Younes, who developed ORP, with Dr. James Walsh and colleagues from St. Luke’s Hospital in Missouri and published in the prestigious journal SLEEP. This study is the first time a close comparison was done between ORP and delta power, a traditional, albeit not well validated, measure used in research. The study concluded ORP is more sensitive to sleep restriction and more closely associated with patient arousability compared to delta power.

By accurately reflecting sleep depth throughout the night, Cerebra ORP is the objective measure needed to evaluate the impact of sleep quality on patient health, with the potential to unlock new advances in sleep disorder diagnosis and treatment.

Harvard Medical school researchers use ORP to predict driving safety in patients with obstructive sleep apnea (OSA)

Sleep apnea is associated with a higher risk of car accidents due to neurocognitive impairment. However, the common diagnostic metric for sleep apnea, the apnea-hypopnea index (AHI), is unable to provide insight into the level of risk for a given severity of OSA.

Research supports the idea that humans, when sleep deprived, begin to sleep more deeply in one half of the brain than the other. This paper hypothesizes that poor synchrony in sleep depth across the brain is a result of sleep deprivation due to frequent respiratory events.

Ali Azarabarzin and his fellow researchers at the Harvard Medical School, were able to use Cerebra’s ORP metric to determine whether differences in sleep depth across the right and left hemisphere of the brain identified sleep apnea patients at increased risk of motor vehicle accidents.

Published in the Journal of Sleep Research, they found, in the study of 1,378 sleep apnea patients, individuals with a higher degree of synchronization in sleep across the right and left halves of the brain had a significantly lower (62%) risk of motor vehicle crashes, than those with the lowest synchronization in sleep across the brain.

“We are seeing the growing impact ORP is having on the field of sleep medicine,” says Gardiner, “not just in research but increasingly in clinical practice as physicians use ORP to better understand their patients’ sleep quality to better guide diagnosis and treatment.”


For more information, contact:

Mary Fearon


289 440 2654


About Cerebra

Cerebra Health Inc. (Cerebra) is a Canadian digital health and virtual care company transforming the future of sleep diagnosis and therapy. Cerebra’s proprietary sleep depth metric ORP is the first highly validated measure of sleep depth and is being used by researchers and clinicians around the world to gain greater insight into an individual’s sleep and enable the personalization of treatments for sleep disorders.

Cerebra Medical, a wholly-owned subsidiary of Cerebra Health, operates an ISO 13485:2016 certified Quality Management System for the design, development, and manufacture of EEG sleep monitoring systems and medical device software for collection and analysis of physiological data recorded during sleep.  Cerebra Medical holds an MDSAP certificate in conformance with the requirements of Health Canada and FDA.



ORP As a Measure of Sleep Depth:

Citation: Magdy Younes, Paula K Schweitzer, Kara S Griffin, Robert Balshaw, James K Walsh, Comparing two measures of sleep depth/intensity, Sleep, Volume 43, Issue 12, December 2020, zsaa127, https://doi.org/10.1093/sleep/zsaa127

ORP & Driving Publication:

Citation: Azarbarzin A, Younes M, Sands SA, Wellman A, Redline S, Czeisler CA, Gottlieb DJ. Interhemispheric sleep depth coherence predicts driving safety in sleep apnea. J Sleep Res. 2020 May 22:e13092. https://pubmed.ncbi.nlm.nih.gov/32441843/