ORP – A Highly Validated Measure of Sleep Depth:
The Sleep Homeostatic Response to Sleep Deprivation in Humans is Heritable - authors study identical and fraternal twins and investigate if the need for deep sleep after sleep deprivation is inheritable. Deep sleep after sleep deprivation measured by both delta waves and ORP was highly related to genetics with similar patterns in identical twins.
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Odds Ratio Product of Sleep EEG as a Continuous Measure of Sleep State - develop and validate an algorithm that provides a continuous estimate of sleep depth from the electroencephalogram (EEG). Results support the use of the odds ratio product (ORP) as a continuous measure of sleep depth.
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A novel EEG marker predicts perceived SLEEPINESS AND poor sleep quality - to determine if a novel EEG-derived continuous index of sleep depth/alertness, the Odds Ratio Product (ORP), predicts self-reported daytime sleepiness and poor sleep quality in two large population-based cohorts. The article found that ORP wake may provide valuable objective mechanistic insight into physiological hyperarousal.
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Representations of temporal sleep dynamics: Review and synthesis of the literature
- a structured overview of approaches to represent temporal sleep dynamics.
Among the different approaches mentioned, Odds Ratio Product (ORP) was highlighted as a
measure of sleep depth with emphasis on spectral power analysis.
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New and Emerging Approaches to Better Define Sleep Disruption and Its Consequences
- emerging approaches to define sleep disruption. Made mention of Odds Ratio Product (ORP) as an attempt to define sleep and advocates for development of practical, inexpensive methods to assess sleep and circadian disruption. The article also advocates for multisystem approach to capture diverse impacts that sleep, and circadian disruption have on health and wellbeing.
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Comparing Two Measures of Sleep Depth/intensity - Compares delta spectral power (delta) and odds ratio product (ORP) as measures of sleep depth during sleep restriction with placebo or a drug that increases delta.
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Odds Ratio Product: A Measure of Sleep Homeostasis Following Prolonged Wakefulness - Odds ratio product (ORP) is a continuous index of sleep depth derived from the relation of EEG powers in different frequency ranges to each other.
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Odds Ratio Product as a Measure of Sleep Depth During REM Sleep: Effects on REM Duration and REM Sleep Fragmentation - The odds ratio product (ORP) is a new highly validated electroencephalogram biomarker of sleep depth. ORP during REM sleep varies considerably among individuals. Whether ORP reflects sleep depth also in REM sleep is unknown. We hypothesized that subjects with high REM ORP are more prone to REM sleep fragmentation.
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Assessment of Intervention-Related Changes in Non-Rapid-Eye-Movement Sleep Depth: Importance of Sleep Depth Changes Within Stage 2 - Depth of sleep within non-rapid-eye-movement (non-REM) stage-2 (N2-depth) varies from being nearly similar to stage-1 to nearly similar to stage-3. Differences in N2-depth are not captured by conventional indices of sleep depth (N1-N3 times, arousal/awakening index) when comparing sleep depth under different conditions.
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Change in Sleep Depth Across the Night as a Measure of Sleep Adequacy - Reduction in sleep depth across the night as measured by ORP, but not by delta power, is significantly correlated with reduced objective sleepiness following sleep restriction. ORP may be a useful index that reflects sleep adequacy during the night.
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The Case for Using Digital EEG Analysis in Clinical Sleep Medicine - Evaluation of sleep in clinical polysomnograms continues to rely almost exclusively on visual scoring that implements rules proposed by Rechtschaffen and Kales nearly 50 years ago.
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Correlation Between Sleep Depth in the Right and Left Cerebral Hemispheres Following Sleep Deprivation, Restriction or Noise Exposure - Odds-Ratio-Product (ORP) is a highly-validated continuous index of sleep depth (range 0= deep sleep; 2.5 = full wakefulness). ORP values fluctuate within this range as sleep state changes between wake and different sleep stages. The correlation between sleep depth in the right and left hemispheres deteriorates following sleep deprivation, restriction or noise-induced sleep fragmentation.
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Traffic Noise and its Impact on Sleep Depth Measured by the Odds Ratio Product - ORP increased during aircraft, road and rail noise and was sensitive enough to detect greater responses to road and rail noise than to aircraft noise.
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Changes in Sleep Depth following Sleep Deprivation Assessed by Three Methods - In the last 1.5 hours of sleep after 36 hours of sleep deprivation, delta power showed nearly full recovery to baseline, but ORP and AWI suggested only moderate recovery. Delta power may not be a sensitive measure of sleep depth.
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Assessment of Sleep Depth and Propensity During Sleep Restriction Using the Odds Ratio Product - after sleep restriction, ORP decreased during wake, showing sensitivity to sleep pressure. It decreased during all sleep stages as more nights of sleep restriction were added.
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A Comparison of the Effects of Gaboxadol and Sleep Restriction on Sleep Depth Assessed by the Odds Ratio Product - one dose of gaboxadol reduced ORP and arousal index to the same level as 4 nights of sleep restriction.
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Maturational Trajectories of Non-Rapid Eye Movement Slow Wave Activity and Odds Ratio Product in a Population - Based sample of youth: ORP increased with age across adolescence. Slow wave activity decreased across adolescence and plateaued in early adulthood, but the patterns of decline differed in males and females.
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Applying ORP to Obstructive Sleep Apnea (OSA) and Other Sleep Disorders
Contribution of Obstructive Sleep Apnea to Disrupted Sleep in a Large Clinical Cohort of Patients with Suspected OSA
- The study examines 576 split nights (first half diagnostic, second half on PAP) to assess changes in ORP metrics and architectures after PAP treatment. They also compare results with changes in ORP metrics across the night by using full diagnostic PSG studies (760) to control for changes in sleep depth through the night. The analyses of the PAP effects showed the greatest changes in sleep depth assessed with ORP NREM and ORP TRT in 3 ORP Sleep Architecture Types and only in patients with severe sleep apnea (AHI >30). The response to PAP was attenuated or reversed for mild/moderate OSA. This result highlights the advantage of using ORP to evaluate OSA severity and response to PAP therapy. When comparing to changes in the full night diagnostic studies it was evident that the changes in the split studies were due to PAP and not to changes in sleep through the night.
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Adherence Index: sleep depth and nocturnal hypoventilation predict long-term adherence with positive airway pressure therapy in severe obstructive sleep apnea
- The study investigated if conventional sleep metrics and measures of sleep depth using Odds Ratio Product (ORP) measured during diagnostic PSG could predict 12 month adherence with positive airway pressure (PAP) therapy in those with severe OSA (average AHI = 72.2). Adherence with PAP therapy was collected 1,3,6 and 12 months after the PAP trial. An Adherence Index incorporating diagnostic AHI, mean nocturnal SpO2, and ORPNREM was a significant predictor of adherence at 12 months.The "Adherence Index" has yet to be used in clinical practice but has potential to assist in the development of a precision-based approach to PAP management and the identification of patients who may require additional resources to promote adherence.
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Sleep Architecture Based on Sleep Depth and Propensity: Patterns in Different Demographics and Sleep Disorders and Association with Health Outcomes
- a novel way to characterize Odds Ratio Product (ORP) based on fractions of total recording time spent at different depths of sleep or wakefulness. Records from the Sleep Heart Health Study and a study of performance deficit following sleep deprivation in twins were analyzed and nine base ORP Sleep Architecture profiles which provide a framework to assist in diagnosing, managing, and understanding the underlying mechanisms of sleep disorders were identified. It was concluded that the new ORP architecture approach may provide new tools for diagnosing, classifying, and managing sleep disorders.
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The Odds Ratio Product (An Objective Sleep Depth Measure): Normal Values, Repeatability, and Change With CPAP in Patients with OSA - investigation seeks to elucidate normal values of non-rapid eye movement ORP (ORPNR) in healthy individuals, repeatability of the measure, and the change in ORPNR following continuous positive airway pressure (CPAP) treatment.
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Mechanism of Excessive Wake Time When Associated with Obstructive Sleep Apnea or Periodic Limb Movements - It is uncertain whether obstructive apnea (OSA) or periodic limb movements (PLMs) contribute to excessive wake time (EWT) when EWT and these disorders coexist. We hypothesized that such EWT is an independent disorder related to central regulation of sleep depth.
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Characteristics and Reproducibility of Novel Sleep EEG Biomarkers and their Variation with Sleep Apnea and Insomnia in a Large Community-Based Cohort - Results serve as bases for interpreting studies that utilize novel sleep EEG biomarkers and identify characteristic EEG changes that very with age, gender, and may help distinguish insomnia from OSA.
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Immediate Post-Arousal Sleep Dynamics: an Important Determinate of Sleep Stability in Obstructive Sleep Apnea - Arousability from sleep is increasingly recognized as an important determinate of the clinical spectrum of sleep disordered breathing (SDB). Patients with SDB display a wide range of arousability. We hypothesized that differences in the speed with which sleep deepens following arousals/awakenings (post-arousal sleep dynamics) is a major determinate of these differences in arousability in patients with SDB.
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Comparison of Odds Ratio Product and Other Polysomnographic Metrics Among Responders and Non-Responders to Upper Airway Stimulation treatment of Obstructive Sleep Apnea- OSA fails to improve in 22% of patients who receive UAS as defined by a >50% reduction of Apnea-Hypopnea Index (AHI) and an AHI <20 events/hour. Light sleep may predict UAS failure in that it may limit the stimulus strength that can be applied. The odds ratio product (ORP) is a novel polysomnographic (PSG) metric of sleep depth. We hypothesized that ORP values prior to surgery will be higher (lighter sleep) in non-responders. Having markers that predict surgical success can help reduce unnecessary surgeries.
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Relation Between Arousability and Outcome of Upper Airway Stimulation for Apnea Reduction (STAR) Trial - Upper airway stimulation (UAS) is an innovative surgical treatment for obstructive sleep apnea; however, the treatment failure rate is approximately 22%. Easy arousability may limit the tolerability of stimulation and, by extension, it's effectiveness. The odds ratio product (ORP) is a continuous electroencephalographic metric of arousal propensity (range:0 [deep sleep] to 2.5 [full wakefulness]), and its rate of decline after arousal (ORP-9) is a risk factor for susceptibility to arousal in the presence of frequent arousal stimuli. We hypothesized that individuals with deeper sleep (low average ORP and low ORP-9) are more likely to respond UAS.
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Arousal Intensity is a Distinct Pathophysiological Trait in Obstructive Sleep Apnea -average arousal intensity was not related to the previous respiratory event, which suggests that it is a distinct trait of OSA. Greater pharyngeal muscle responses and ventilatory response occurred with greater arousal intensity.
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Relationship Between Neurobehavioral Function And Sleep Depth In Children With Obstructive Sleep Apnea - In children with OSA receiving early adenotonsillectomy, improvements in executive function and hyperactivity were partially related to changes in sleep depth.
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Characteristics and Reproducibility of Novel Sleep EEG Biomarkers and their Variation with Sleep Apnea and Insomnia in a Large Community-Based Cohort - Wake ORP was higher in patients with insomnia symptoms, and lower in patients with OSA, showing different levels of sleep pressure. Non-REM ORP was higher in both insomnia and OSA, showing shallow sleep depth.
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Medical Outcomes using ORP & Non-ORP Metrics
Sleep and Pathological Wakefulness at the Time of Liberation from Mechanical Ventilation (SLEEWE). A Prospective Multicenter Physiological Study - In this study (SLEEWE [ Effect of Sleep Disruption on the Outcome of Weaning from Mechanical Ventilation]), we aimed to investigate polysomnographic indexes as well as a continuous index for evaluating sleep depth, the odds ratio product (ORP), to determine whether abnormal sleep or wakefulness is associated with the outcome of spontaneous breathing trials.
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Sleep Propensity and Sleep Apnea-Specific Hypoxia are Associated with Excessive Daytime Sleepiness - Exessive daytime sleepiness is a hallmark of obstructive sleep apnea (OSA). Previous research reports substantial variability in patient-reported sleepiness for a given OSA severity, i.e., apnea-hypopnea index (AHI). We assessed the separate associations between respiratory event related desaturation, as a measure of intermittent hypoxia, and sleep depth on daytime sleepiness.
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Association of Novel Measures of Sleep Disturbances with Blood Pressure: the Multi-Ethnic Study of Atherosclerosis.- ORP was not associated with blood pressure, but higher airflow limitation was associated with lower systolic blood pressure, and hypoxia was associated with higher systolic and diastolic blood pressure.
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Effects of Sedatives on Sleep Architecture Measured with Odds Ratio Product in Critically Ill Patients - unsedated critically ill patients spent less time in stable sleep than normal sleepers, but sedation with propofol or dexmedetomidine resulted in deeper and more normal sleep.
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The Sleep Apnea-Specific Hypoxic Burden Predicts Incident Heart Failure - the hypoxic burden of sleep apnea in men was related to greater heart failure even after controlling for relevant demographics. This research suggests that having an index of hypoxias could be useful for identifying patients at risk.
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The Sleep Apnea-Specific Pulse-Rate Response Predicts Cardiovascular Morbidity and Mortality - OSA patients who have a higher pulse-rate response to apneas and hypopneas have greater cardiovascular risk.
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Silent Hypoxemia in COVID-19 Patients - this review highlights the important respiratory and neurological factors that may play a role in variability in silent hypoxaemia between patients with COVID-19.
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Non-ORP Metrics
Spindles are Highly Heritable as Identified by Different Spindle Detectors – this paper supports strong heritability of spindles regardless of the detector method. Sleep spindles in stage N2 sleep is highly heritable, but the heritability differs for individual spindle characteristics and depends on the spindle detector used for analysis.
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Association of Sleep Spindle Characteristics with Executive Functioning in Healthy Sedentary Middle-aged and Older Adults - Both greater spindle density and fast spindle density were associated with better executive functioning and less cognitive decline.
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Characterizing Sleep Spindles in 11,630 Individuals from the National Sleep Research Resource. - This research found that genetic factors significantly contributed to spindle and spectral sleep traits.
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Heritability of Heart Rate Response to Arousals in Twins – The duration of arousals and specific average change in heart rate values seem to be heritable traits.
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Arousal Responses During Overnight Polysomnography and their Reproducibility in Healthy Young Adults. - This research found average arousal intensity and heart rate response to arousal were highly variable among healthy young adults but stable within the same individual.
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Relationship Between Arousal Intensity and Heart Rate Response to Arousal - Arousal intensity was strongly associated with arousal-related tachycardia, and the gain of the relationship varies among subjects. Assessing arousal intensity in PSGs provides additional information that may be clinically relevant.
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Sex and Pubertal Differences in the Maturational Trajectories of Sleep Spindles in the Transition from Childhood to Adolescence: A Population-Based Study - Males had greater changes in spindle density in adolescence, but in early adulthood, females had greater spindle frequency, fast spindle percent, and spindle power. Different characteristics of spindles showed different trajectories over development.
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Maturational Trajectories of Non-rapid Eye Movement Slow Wave Activity and Odds Ratio Product in a Population - based sample of youth: ORP increased with age across adolescence. Slow wave activity decreased across adolescence and plateaued in early adulthood, but the patterns of decline differed in males and females.
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Relation Between Arousability and Outcome of Upper Airway Stimulation in the Stimulation for Apnea Reduction (STAR) Trial - While there were no significant differences for the ORP between responders and nonresponders receiving upper airway stimulation, a shallower sleep depth was associated with being more likely to respond to the treatment.
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Scoring of Polysomnographic Features and Sleep Testing
Revisiting level II sleep studies in the era of COVID-19: a theoretical economic decision model in patients with suspected obstructive sleep apnea - Using a theoretical decision model, a preliminary cost framework is used to assess the potential role of LII studies in OSA assessment.
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Performance of a New Portable Wireless Sleep Monitor - With automatic scoring and minor editing, the Prodigy results were highly similar to manual scoring by sleep technicians.
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Accuracy of Automatic PSG Scoring using Frontal Electrodes - The use of frontal electrodes was highly similar to the use of central electrodes for sleep variables with automatic scoring, suggesting that the use of forehead devices can provide high quality data without needing more complicated home setups.
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Agreement in Computer-assisted Manual Scoring of Polysomnograms Across Sleep Centers - there was very good agreement between scorers at different laboratories when using computer-assisted manual scoring with the AASM recommended criteria, although agreement was not as high when using alternate forms of criteria.
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Performance of an Automated Polysomnography Scoring System versus Computer-assisted Manual Scoring - Automatic scoring produces comparable results to those obtained by experienced technologists therefore reduces cost and improves reproducibility.
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Utility of Technologist Editing of Polysomnography Scoring Performed by a Validated Automatic System - Comprehensive editing of a well-validated automatic scoring system is highly inefficient and editing time does not reflect unreliable scoring.
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Staging Sleep in Polysomnograms: Analysis of Inter-Scorer Variability – to determine the reasons for inter-scorer variability in sleep staging of polysomnograms, 56 PSGs were scored and months later, same technologists edited their own scoring. The PSGs were then autoscored, and technologists edited them epoch by epoch. The research found that disagreements were between awake/NREM, N1/N2, and N2/N3 sleep and that availability of digitally identified events like spindles or calculated variables like depth of sleep and delta wave duration may reduce scoring variability.
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Reliability of the American Academy of Sleep Medicine Rules for Assessing Sleep Depth in Clinical Practice. - Polysomnograms of 70 females were scored by 10 highly trained sleep technologists from different academic sleep laboratories to determine the range of time in stage N1 and N3. Research found that manual scoring of non-rapid eye movement sleep stages is highly unreliable among highly trained, experienced technologists.
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Enhancements to the Multiple Sleep Latency Test - Determining the time course of sleep depth during multiple sleep latency test naps, the research found that sleep onset latency occurred almost every time ORP was between 1.0 and 2.0.
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Sports and Athletic Performance
The Clinical Validation of the Athlete Sleep Screening Questionnaire: An Instrument to Identify Athletes that Need Further Sleep Assessment - Previous research has established that general sleep screening questionnaires are not valid and reliable in an athlete population. The Athlete Sleep Screening Questionnaire (ASSQ) was developed to address this need. While the initial validation of the ASSQ has been established, the clinical validity of the ASSQ has yet to be determined. The main objective of the current study was to evaluate the clinical validity of the ASSQ.
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Sleep in Elite Multi-Sport Athletes: Implications for Athlete Health and Wellbeing - To investigate the prevalence of clinical relevant sleep problems in elite multi-sport athletes and their associations with sleep hygiene, general heath, mood, chronotype, and injury.
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How to Manage Travel Fatigue and Jet Lag in Athletes? A Systematic Review of Interventions - We investigated the management of travel fatigue and jet lag in athlete populations by evaluating studies that have applied non-pharmacological interventions (exercise, sleep, light and nutrition), and pharmacological interventions (melatonin, sedatives, stimulants, melatonin analogues, glucocorticoids and antihistamines) following long-haul transmeridian travel-based, or laboratory-based circadian system phase-shifts.
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Sleep and the Athlete: Narrative Review and 2021 Expert Consensus Recommendations - Elite athletes are particularly susceptible to sleep inadequacies, characterized by habitual short sleep (<7 hours/night) and poor sleep quality (eg, sleep fragmentation). Athletic performance is reduced by a night or more without sleep, but the influence on performance of partial sleep restriction over 1-3 nights, a more real-world scenario, remains unclear.
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Managing Travel Fatigue and Jet Lag in Athletes: A Review and Consensus Statement - outlines fundamental principles and interventions to consider for both the assessment and management of travel fatigue and jet lag. Includes travel toolboxes including strategies for pre-flight, during flight and post-flight.
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