Comparative Effectiveness of Supine Avoidance versus Continuous Positive Airway Pressure for Treating Supine-isolated Sleep Apnea: A Clinical Trial.

Rationale: About 20-35% of patients with obstructive sleep apnea (OSA) have supine-isolated OSA, for which supine sleep avoidance could be an effective therapy. However, traditional supine discomfort-based methods show poor tolerance and compliance to treatment and so cannot be recommended. Supine alarm devices show promise, but evidence to support favorable adherence to treatment and effectiveness at reducing excessive daytime sleepiness compared with continuous positive airway pressure (CPAP) remains limited. Objectives: To establish if alarm-based supine-avoidance treatment in patients with supine-isolated OSA is noninferior to CPAP in reducing daytime sleepiness. Methods: After baseline questionnaire administration and in-home supine-time and polysomnography assessments, patients with supine-isolated OSA and Epworth Sleepiness Scale scores ⩾8 were randomized to ⩾6 weeks of supine-avoidance or CPAP treatment, followed by crossover to the remaining treatment with repeat assessments. Noninferiority was assessed from change in Epworth Sleepiness Scale with supine avoidance compared with CPAP using a prespecified noninferiority margin of 1.5. Average nightly treatment use over all nights and treatment efficacy and effectiveness at reducing respiratory disturbances were also compared between treatments. Results: The reduction in sleepiness score with supine avoidance (mean [95% confidence interval], -1.9 [-2.8 to -1.0]) was noninferior to that with CPAP (-2.4 [-3.3 to -1.4]) (supine avoidance-CPAP difference, -0.4 [-1.3 to 0.6]), and the lower confidence limit did not cross the noninferiority margin of 1.5 (P = 0.021). Average treatment use was higher with supine avoidance compared with CPAP (mean ± standard deviation, 5.7 ± 2.4 vs. 3.9 ± 2.7 h/night; P < 0.001). Conclusions: In patients with supine-isolated OSA, vibrotactile supine alarm device therapy is noninferior to CPAP for reducing sleepiness and shows superior treatment adherence. Clinical trial registered with www.anzctr.org.au (ACTRN 12613001242718).

Affordable housing through the Low-Income Housing Tax Credit program and opioid overdose emergency department visits.

INTRODUCTION: The United States continues to experience an opioid overdose crisis. As a key social determinant of health, housing insecurity may contribute to initiation of substance use and can threaten outcomes for those with substance use disorders by increasing stress, risky substance use, discontinuity of treatment, and return to use, all of which may increase the risk of overdose. The Low-Income Housing Tax Credit (LIHTC) program supports access to rental housing for low-income populations. By facilitating access to affordable housing, this program may improve housing security, thereby reducing overdose risk. METHODS: We used data from LIHTC Property Data and the State Emergency Department Database (SEDD) to identify the number of LIHTC units available and opioid overdoses discharged from the emergency department (ED) in 13 states between 2005 and 2014. RESULTS: Between 2005 and 2014, mean opioid overdose ED visits were higher in states with fewer LIHTC units (<28 LIHTC units per 100,000 population) at 26.5 per 100,000 population as compared to states with higher LIHTC units (≥28 LIHTC units per 100,000 population) at 21.1 per 100,000. We find that greater availability of LIHTC units was associated with decreased rates of opioid overdose ED visits (RR 0.94; CI 0.90, 1.00). CONCLUSIONS: Given the importance of housing as a key social determinant of health, the provision of affordable housing may mitigate substance misuse and prevent nonfatal opioid overdose.

Efficacy of a Novel Telehealth Application in Health Behavior Modification and Symptomology in Military Service Members at Risk for Post-traumatic Osteoarthritis.

INTRODUCTION: Mobile applications (apps) may be beneficial to promote self-management strategies to mitigate the risk of developing post-traumatic osteoarthritis in military members following a traumatic knee injury. This study investigated the efficacy of a mobile app in facilitating behavior modification to improve function and symptomology among military members. MATERIALS AND METHODS: This is a preliminary pre and post hoc analysis of a randomized control trial. The MARX scale, Intermittent and Constant Osteoarthritis Pain (ICOAP) questionnaire, and the Knee Injury and Osteoarthritic Outcome Score Readiness to Manage Osteoarthritis Questionnaire were completed at baseline, 6-week, 6-month, and 12-month follow-up. Participants in the treatment arm completed the System Usability Scale. Data were analyzed using descriptive statistics, the Wilcoxon sum of ranks test, the Wilcoxon signed-rank test, and Cohen's d effect size. RESULTS: A total of 28 participants were included. Between-group differences for baseline and 6-week follow-up were significantly improved in the injured knee ICOAP constant pain score for the treatment group (treatment: -4.2 ± 12, 95% CI: -11.5, 3.1; control: 5.5 ± 9.9, 95% CI: 0.9, 10.1; P = .035, effect size = 0.905). Within-group differences for baseline and 6-week follow-up demonstrated a significant decline in the injured knee ICOAP constant pain score among the control group (signed-rank: 16.0, P = .031, Cohen's d = 0.339). No other significant differences were observed. A good System Usability Scale score for usability was found (76.6 ± 8.8). CONCLUSIONS: These results indicate that the mobile app is easy to use and may contribute to improved constant pain symptomology for patients at risk for post-traumatic osteoarthritis.

Establishing the acute physiological and sleep disruption characteristics of wind farm versus road traffic noise disturbances in sleep: a randomized controlled trial protocol.

Study Objectives: Despite the global expansion of wind farms, effects of wind farm noise (WFN) on sleep remain poorly understood. This protocol details a randomized controlled trial designed to compare the sleep disruption characteristics of WFN versus road traffic noise (RTN). Methods: This study was a prospective, seven night within-subjects randomized controlled in-laboratory polysomnography-based trial. Four groups of adults were recruited from; <10 km away from a wind farm, including those with, and another group without, noise-related complaints; an urban RTN exposed group; and a group from a quiet rural area. Following an acclimation night, participants were exposed, in random order, to two separate nights with 20-s or 3-min duration WFN and RTN noise samples reproduced at multiple sound pressure levels during established sleep. Four other nights tested for continuous WFN exposure during wake and/or sleep on sleep outcomes. Results: The primary analyses will assess changes in electroencephalography (EEG) assessed as micro-arousals (EEG shifts to faster frequencies lasting 3-15 s) and awakenings (>15 s events) from sleep by each noise type with acute (20-s) and more sustained (3-min) noise exposures. Secondary analyses will compare dose-response effects of sound pressure level and noise type on EEG K-complex probabilities and quantitative EEG measures, and cardiovascular activation responses. Group effects, self-reported noise sensitivity, and wake versus sleep noise exposure effects will also be examined. Conclusions: This study will help to clarify if wind farm noise has different sleep disruption characteristics compared to road traffic noise.

The Association of Low-Income Housing Tax Credit Units and Reports of Child Abuse and Neglect.

INTRODUCTION: Poverty broadly and financial stress owing to housing insecurity specifically are associated with an increased risk of child maltreatment. Therefore, it is possible that a program designed to increase access to affordable housing such as the Low-Income Housing Tax Credit program could reduce child maltreatment. The purpose of this study is to examine the association of the availability of housing units through the Low-Income Housing Tax Credit Program with the rates of child maltreatment reports, including reports for physical abuse and neglect, at the state and county levels. METHODS: Data were from the 2005‒2015 National Child Abuse and Neglect Data System and the Low-Income Housing Tax Credit Program database. Generalized estimating equations were conducted in 2021 to calculate rate ratios and 95% CIs, adjusting for relevant confounders. RESULTS: At the state level, ≥25 compared with <25 Low-Income Housing Tax Credit Program units per 100,000 population was associated with a lower rate of overall child maltreatment (i.e., neglect and physical abuse; rate ratio=0.96, 95% CI=0.93, 0.99), neglect (rate ratio=0.96, 95% CI=0.94, 0.99), and physical abuse (rate ratio=0.96, 95% CI=0.93, 1.00) reports. Similarly, at the county level, ≥1 compared with 0 Low-Income Housing Tax Credit Program units per 100,000 population was associated with a lower rate of overall child maltreatment (rate ratio=0.94, 95% CI=0.92, 0.97), neglect (rate ratio=0.96, 95% CI=0.93, 0.98), and physical abuse (rate ratio=0.94, 95% CI=0.91, 0.98) reports. CONCLUSIONS: Increasing access to affordable housing may be an effective strategy to reduce child maltreatment at both the state and county levels.

Affordable housing through the low-income housing tax credit program and intimate partner violence-related homicide.

The most severe outcome of intimate partner violence (IPV) is IPV-related homicide. Access to affordable housing may both facilitate exit from abusive relationships and reduce financial stress in intimate relationships, potentially preventing IPV-related homicide. We examined the association of the availability of rental housing through the Low-Income Housing Tax Credit (LIHTC) program, a federal program providing tax incentives to support the development of affordable housing, with IPV-related homicide and assessed whether this association differed by eviction rates at the state-level. We used 2005-2016 National Violent Death Reporting System, LIHTC Property, and Eviction Lab data for 13 states and compared the rate of IPV-related homicide in state-years with ≥30 to state-years with <30 LIHTC units per 100,000 population, overall and stratified by eviction rates. We conducted analyses in fall 2020. Adjusting for potential state-level confounders, the rate of IPV-related homicide in state-years with ≥30 LIHTC units per 100,000 population was lower than in state-years with <30 LIHTC units per 100,000 population (RR = 0.89, 95% CI 0.81, 0.98). The reduction in the rate of IPV-related homicide was slightly larger in state-years with higher eviction rates (≥3500 evictions per 100,000 renter population; RR = 0.83, 95% CI 0.74, 0.93) compared to state-years with lower eviction rates (<3500 evictions per 100,000 renter population; RR = 0.91, 95% CI 0.81, 1.03). Overall, at the state-level, increased availability of affordable housing through the LIHTC program was associated with lower rates of IPV-related homicide. Increasing the availability of affordable housing may be one tool for preventing IPV-related homicide.

Sleep-Disordered Breathing in Patients with Motor Neurone Disease: One Size Does Not Fit all.

INTRODUCTION: Sleep-disordered breathing (SDB) in patients with motor neurone disease (MND) is normally attributed to hypoventilation due to muscle weakness. However, we have observed different patterns of SDB among MND patients referred for non-invasive ventilation, which do not appear to be explained by respiratory muscle weakness alone. AIM: The aim of this study was to examine the characteristics of SDB in MND. METHODS: This is a retrospective analysis of sleep studies (using polysomnography [PSG]), pulmonary function tests, and arterial blood gases in MND patients referred to a tertiary sleep medicine service for clinical review. Sleep apnoeas were characterised as obstructive or central, and to further characterise the nature of SDB, hypopnoeas were classified as obstructive versus central. RESULTS: Among 13 MND patients who had a diagnostic PSG, the mean ± SD age was 68.9 ± 9.8 years, BMI 23.0 ± 4.3 kg/m2, forced vital capacity 55.7 ± 20.9% predicted, and partial pressure of CO2 (arterial blood) 52.7 ± 12.1 mm Hg. A total of 38% of patients (5/13) showed evidence of sleep hypoventilation. The total apnoea/hypopnoea index (AHI) was (median [interquartile range]) 44.4(36.2-56.4)/h, with 92% (12/13) showing an AHI >10/h, predominantly due to obstructive events, although 8% (1/13) also showed frequent central apnoea/hypopnoeas. CONCLUSIONS: Patients with MND exhibit a wide variety of SDB. The prevalence of obstructive sleep apnoea (OSA) is surprising considering the normal BMI in most patients. A dystonic tongue and increased upper-airway collapsibility might predispose these patients to OSA. The wide variety of SDB demonstrated might have implications for ventilator settings and patients' outcomes.

Cognition in schizophrenia improves with treatment of severe obstructive sleep apnoea: A pilot study.

Previous studies have shown that people with schizophrenia have high rates of Obstructive Sleep Apnoea (OSA). Despite this, intervention studies to treat OSA in this population have not been undertaken. The ASSET (Assessing Sleep in Schizophrenia and Evaluating Treatment) pilot study investigated Continuous Positive Airway Pressure (CPAP) treatment of severe OSA in participants recruited from a clozapine clinic in Adelaide. Participants with severe untreated OSA (Apnoea-Hypopnoea Index (AHI) > 30), were provided with CPAP treatment, and assessed at baseline and six months across the following domains: physical health, quality of sleep, sleepiness, cognition, psychiatric symptoms and CPAP adherence. Six of the eight ASSET participants with severe OSA accepted CPAP. At baseline, half of the cohort had hypertension, all were obese with a mean BMI of 45, and they scored on average 1.47 standard deviations below the normal population in cognitive testing. The mean AHI was 76.8 and sleep architecture was markedly impaired with mean rapid eye movement (REM) sleep 4.1% and mean slow wave sleep (SWS) 4.8%. After six months of treatment there were improvements in cognition (BACS Z score improved by an average of 0.59) and weight loss (mean weight loss 7.3 ±â€¯9 kg). Half of the participants no longer had hypertension and sleep architecture improved with mean REM sleep 31.4% of the night and mean SWS 24% of the night. Our data suggests CPAP may offer novel benefits to address cognitive impairment and sleep disturbance in people with schizophrenia.

Obstructive sleep apnoea is more prevalent in men with schizophrenia compared to general population controls: results of a matched cohort study.

OBJECTIVES:: Obstructive sleep apnoea (OSA) may be more common in people with schizophrenia compared to the general population, but the relative prevalence is unknown. Here, we determine the relative prevalence of severe OSA in a cohort of men with schizophrenia compared to representative general population controls, and investigate the contribution of age and body mass index (BMI) to differences in prevalence. METHODS:: Rates of severe OSA (apnoea-hypopnoea index > 30) were compared between male patients with schizophrenia and controls from a representative general population study of OSA. RESULTS:: The prevalence of severe OSA was 25% in the schizophrenia group and 12.3% in the general population group. In subgroups matched by age, the relative risk of severe OSA was 2.9 ( p = 0.05) in the schizophrenia subjects, but when adjusted for age and BMI, the relative risk dropped to 1.7 and became non-significant ( p = 0.17). CONCLUSIONS:: OSA is prevalent in men with schizophrenia. Obesity may be an important contributing factor to the increased rate of OSA.

Choosing an Oronasal Mask to Deliver Continuous Positive Airway Pressure May Cause More Upper Airway Obstruction or Lead to Higher Continuous Positive Airway Pressure Requirements than a Nasal Mask in Some Patients: A Case Series.

STUDY OBJECTIVES: The choice of mask interface used with continuous positive airway pressure (CPAP) therapy can affect the control of upper airway obstruction (UAO) in obstructive sleep apnea (OSA). We describe a case series of four patients with paradoxical worsening of UAO with an oronasal mask and the effect of changing to a nasal mask. METHODS: We retrospectively reviewed the case histories of 4 patients and recorded patient demographics, in-laboratory and ambulatory CPAP titration data, CPAP therapy data, type of mask interface used and potential confounding factors. RESULTS: The 4 cases (mean ± SD: age = 59 ± 16 y; BMI = 30.5 ± 4.5 kg/m(2)) had a high residual apnoea-hypopnea index (AHI) (43 ± 14.2 events/h) and high CPAP pressure requirements (14.9 ± 6.6 cmH2O) with an oronasal mask. Changing to a nasal mask allowed adequate control of UAO with a significant reduction in the average residual AHI (3.1 ± 1.5 events/h). In two of the four cases, it was demonstrated that control of UAO was obtained at a much lower CPAP pressure compared to the oronasal mask (Case one = 17.5 cmH2O vs 12cmH2O; Case two = 17.9 cmH2O vs 7.8 cmH2O). Other potential confounding factors were unchanged. There are various physiological observations that may explain these findings but it is uncertain which individuals are susceptible to these mechanisms. CONCLUSIONS: If patients have OSA incompletely controlled by CPAP with evidence of residual UAO and/or are requiring surprisingly high CPAP pressure to control OSA with an oronasal mask, the choice of mask should be reviewed and consideration be given to a trial of a nasal mask. COMMENTARY: A commentary on this article appears in this issue on page 1209.

Obstructive sleep apnea and schizophrenia: A systematic review to inform clinical practice.

BACKGROUND: Risk factors for obstructive sleep apnea (OSA) are common in people with schizophrenia. Identification and treatment of OSA may improve physical health in this population; however there are no guidelines to inform screening and management. OBJECTIVES: Systematic review to determine, in people with schizophrenia and related disorders: the prevalence of OSA; the prevalence of OSA compared to general population controls; the physical and psychiatric correlates of OSA, associations between antipsychotic medications and OSA; the impact of treatment of OSA on psychiatric and physical health; and the diagnostic validity of OSA screening tools. DATA SOURCES: Medline, EMBASE, ISI Web of Science and PsycINFO electronic databases. Cohort, case-control and cross-sectional studies and RCTs reporting on prevalence of OSA in subjects with schizophrenia and related disorders were reviewed. RESULTS: The prevalence of OSA varied between 1.6% and 52%. The prevalence of OSA was similar between people with schizophrenia and population controls in two studies. Diagnosis of OSA was associated with larger neck circumference, BMI>25, male sex and age>50years. There were no data on physical or psychiatric outcomes following treatment of OSA. The diagnostic utility of OSA screening tools had not been investigated. CONCLUSION: OSA may be prevalent and potentially under-recognized in people with schizophrenia. Further research is required to determine utility of OSA screening tools, the relationships between antipsychotic medications and OSA and any benefits of treating OSA. We propose a strategy for the identification of OSA in people with schizophrenia and related disorders.

Accurate position monitoring and improved supine-dependent obstructive sleep apnea with a new position recording and supine avoidance device.

STUDY OBJECTIVES: Approximately 30% of obstructive sleep apnea (OSA) patients have supine-predominant OSA, and simply avoiding supine sleep should normalise respiratory disturbance event rates. However, traditional supine-avoidance therapies are inherently uncomfortable, and treatment adherence is poor and difficult to monitor objectively. This study evaluated the efficacy of a novel, potentially more acceptable position monitor and supine-avoidance device for managing supine-predominant OSA and snoring. DESIGN AND SETTING: In-laboratory evaluation of position recording accuracy versus video recordings (validation study), and randomized controlled crossover trial of active versus inactive supine-avoidance therapy in the home setting (efficacy study). PATIENTS: 17 patients undergoing in-laboratory sleep studies (validation) and 15 patients with supine-predominant OSA (efficacy). INTERVENTIONS: EFFICACY STUDY: 1 week of inactive and 1 week of active treatment in randomized order, separated by 1 week. MEASUREMENTS AND RESULTS: Agreement between 30-sec epoch-based posture classifications from device versus video records was high (median κ 0.95, interquartile range: 0.88-1.00), and there was good supine time agreement (bias 0.3%, 95%CI: -4.0% to 4.6%). In the efficacy study, apnea-hypopnea index (AHI) and snoring frequency were measured in-home using a nasal pressure and microphone based system during inactive and active treatment weeks. The position monitoring and supine alarm device markedly inhibited supine time (mean ± SEM 19.3% ± 4.3% to 0.4% ± 0.3%, p < 0.001) and reduced AHI (25.0 ± 1.7 to 13.7 ± 1.1 events/h, p = 0.030) but not snoring frequency. CONCLUSIONS: This new position monitoring and supine alarm device records sleep position accurately and improves OSA but not snoring in patients with supine-predominant OSA.

Poor long-term patient compliance with the tennis ball technique for treating positional obstructive sleep apnea.

STUDY OBJECTIVES: Little is known regarding long-term patient compliance with the tennis ball technique (TBT), one of the original simple methods of positional therapy (i.e., avoiding the supine posture during sleep) for posture-dependent obstructive sleep apnea patients. The purpose of this study was to investigate long-term patient compliance with TBT. METHODS: A follow-up questionnaire was mailed to all patients prescribed TBT at the Adelaide Institute for Sleep Health between July 2004 and March 2008 (n = 108). RESULTS: Sixty-seven patients replied to the questionnaire. Baseline demographic/clinical characteristics were not significantly different from non-respondents. Among the respondents, follow-up time was (mean +/- SD) 2.5 +/- 1.0 years. Four (6.0%) reported they were still using TBT (group A); 9 (13.4%) were no longer using TBT, claiming to have learned to avoid the supine position during sleep (group B); and 54 (80.6%) were neither using TBT nor avoiding the supine posture (group C). The main reason for ceasing TBT use in group C was that TBT was too uncomfortable (34/54 patients). CONCLUSIONS: Long-term patient compliance with TBT appears to be very poor, with less than 10% of patients reporting continued use (group A) approximately 30 months after prescription. With most TBT non-compliers reporting it to be too uncomfortable, alternative forms of positional therapy appear to be needed.

Central sleep apnea on commencement of continuous positive airway pressure in patients with a primary diagnosis of obstructive sleep apnea-hypopnea.

INTRODUCTION: Central sleep apnea (CSA) may occur in patients with snoring and obstructive sleep apnea-hypopnea (OSAH) during commencement of continuous positive airway pressure (CPAP) therapy. The presence of CSA may limit the effectiveness of CPAP therapy. The aims of this study were to assess the prevalence of CSA amongst patients starting CPAP for OSAH and to identify possible predictors of this condition. METHODS: We reviewed the polysomnograms (PSGs) and clinical records of 99 consecutive patients with a primary diagnosis of OSAH who were referred for an in-laboratory CPAP titration study. Patients with a CSA Index of > or =5 per hour at or near (+/-1 cm H2O) prescribed CPAP level formed the CSA-CPAP group. The remaining patients made up the noCSA-CPAP group. Demographic, baseline and CPAP titration PSG variables were compared between the 2 two groups. RESULTS: 13 subjects (13.1%) had CSA-CPAP. Patients with and without CSA-CPAP did not differ with respect to age or body mass index. 46% of patients with CSA-CPAP had CSA on their baseline PSGs compared with 8% in the noCSA-CPAP group (p <0.01). CSA-CPAP patients also had a higher apnea-hypopnea index (72.1 vs. 52.7 p = 0.02), a higher arousal index (43.3 vs. 29.2 p <0.01), and a higher mixed apnea index (6.8 vs. 1.3 p = 0.03), on their baseline PSGs. Therapeutic CPAP could not be determined in 2 CSA-CPAP patients due to a very high frequency (of severe) central apneas. In the remaining 11, the CPAP prescription to eliminate obstructive events was higher than in the noCSA-CPAP group (11.0 vs. 9.3 p = 0.08). AHI was greater both at or near prescribed CPAP (48.8 vs. 6.7 p <0.01) and overall (47.4 vs. 14.9 p <0.01). A history of ischemic heart disease or heart failure was more frequent amongst patients with CSA-CPAP than those without (p = 0.03). CONCLUSION: A significant minority of patients with a primary diagnosis of OSAH have either emergence or persistence of CSA on CPAP. Risk factors include male sex, history of cardiac disease, and CSA on baseline PSG.

Mild hypoxia does not suppress auditory arousal from NREM sleep.

STUDY OBJECTIVES: The depressive effects of hypoxia on the central nervous system are well known. The purpose of this study was to determine the influence of mild overnight hypoxia on the ability of healthy individuals to arouse from non-rapid-eye-movement (NREM) sleep to auditory tones. DESIGN: Randomized cross-over. SETTING: Participants slept in a sound-insulated room with the physiologic recordings and experimental interventions controlled from a separate room. PARTICIPANTS: Eleven healthy men aged 18 to 24 years. INTERVENTIONS: On separate nights, participants were exposed to mild overnight hypoxia (SaO2 approximately 90%) or medical air in single-blind fashion. During established sleep, subjects were administered 1 of 10 auditory tones (500 Hz, 54-90 dB, 5 seconds duration) via earphones, or a sham tone (recording period with no tone). MEASUREMENTS AND RESULTS: The probability and intensity of arousal responses in the 30 seconds following tones or shams were compared between gas conditions and between stage 2 and slow-wave sleep. Arousal probability and intensity increased with tone intensity and were significantly lower during slow-wave compared with stage 2 sleep but were not different between hypoxia and normoxia nights. CONCLUSION: These data suggest that mild overnight hypoxia does not impair the neural mechanisms involved in arousal from sleep to auditory stimuli.

Noninvasive cardiovascular markers of acoustically induced arousal from non-rapid-eye-movement sleep.

STUDY OBJECTIVES: Changes in cardiovascular measures such as heart rate (HR) and pulse transit time (PTT) have been advocated as sensitive markers of autonomic arousal from sleep. In animal studies, alerting stimuli produce particularly marked skin vascular responses. We hypothesized that changes in skin vascular conductance would provide more sensitive markers of autonomic arousal during sleep compared to central cardiovascular response measures such as HR and PTT. DESIGN: Cardiovascular responses to auditory-induced arousals were recorded during overnight sleep studies. SETTING: Sleep disorders unit in a 270-bed teaching hospital. PARTICIPANTS: Eleven young healthy male subjects. INTERVENTIONS: Throughout ovemight sleep studies, auditory tones (5-second duration, 54-90 decibels, 22-56 per subject) were presented during non-rapid-eye-movement sleep. Beat-by-beat HR, PTT, laser-Doppler fingertip skin blood flow (SBF) and finger and ear photoplethysmogram pulse wave amplitudes (PWA) were measured in the 20 seconds preceding and 30 seconds following each tone and compared to control measurements obtained during 50-second periods of recording with no stimulus (no tone, 6-22 per subject). Electroencephalographic (EEG) arousals were scored according to standard criteria (American Sleep Disorders Association) into no discemible, 3- to 10-second duration, or 10- to 15-second duration arousals. Poststimulus cardiovascular measurements were expressed as a percentage of the prestimulus mean and response magnitudes quantified from peak responses and the area under the poststimulus response curve. The ability of each cardiovascular response measure to discriminate EEG arousals (EEG changes lasting more than 3 seconds) was assessed from the area under the receiver operating characteristic (ROC) curve. MEASUREMENTS AND RESULTS: There were no significant changes in any cardiovascular parameter during control recordings. In contrast to all other parameters, finger PWA and SBF decreased following tones that produced no discernible EEG arousal (P < 0.05). A significant HR rise and decreases in all cardiovascular measures occurred with greater than 3-second arousals, with longer duration arousals generally exhibiting larger responses. Conventional EEG arousals (greater than 3 seconds) were relatively poorly detected from HR responses (ROC area HR rise 0.80 +/- 0.04) compared to changes in SBF (0.85 +/- 0.02), PTT (0.85 +/- 0.03) and finger PWA (0.90 +/- 0.01). CONCLUSIONS: Decreases in skin vascular conductance (finger PWA and SBF) provide sensitive markers of autonomic arousal during sleep. They are at least as sensitive as PTT for detecting conventionally scored EEG arousals and may be more sensitive in detecting "subcortical" arousals.

Insomniacs' perception of wake instead of sleep.

STUDY OBJECTIVES: To establish if insomniacs' underestimation of sleep time is due to reduced ability to discriminate between sleeping and waking states. DESIGN: Two night's home polysomnography were compared to sleep diaries. Five laboratory nights employed a series of recorded questions regarding perception of prior sleep-wake state, which were presented during sustained wake and interrupted Stage 2 and REM sleep. SETTING: Sleep laboratory and participants' homes. PARTICIPANTS: Fourteen insomniacs were compared to 8 good sleepers. Mean age for both groups was 58 years. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: A signal detection theory analysis was applied to participants' responses to questions presented overnight in the laboratory concerning judgement of prior sleep-wake state and confidence in their decision. Insomniacs had reduced sleep-wake discriminability in addition to a greater bias toward reporting prior wakefulness in the laboratory compared to good sleepers. These measures correlated significantly with the degree of underestimation of total sleep and overestimation of wake recorded at home. CONCLUSIONS: Insomniacs' underestimation of total sleep time is the product of prior sleep being misperceived as wake time upon awakening overnight. This misperception may play a role in the perpetuation of insomnia.