Minutes Of Sleep Research Articles

Can Sleep Duration Help Explain Differences in the Happiness Index Across Nations?

Abstract Inadequate sleep is an important public health problem that can affect one in every three adults; however, it received little attention in the economics of happiness research. The objective of this article is to examine whether sleep adequacy contributes to the explanation of variation in happiness index levels across countries. Analysis was undertaken using ordinary least squares regression method. The dependent variable is the self-reported happiness index developed by the Gallup poll and published in the World Happiness Report. Two alternative model specifications were used. The first included average sleep minutes per country, GDP per capita(purchasing power parity), unemployment rate, and environmental performance index. The second model specification included average sleep minutes per country, GDP (purchasing power parity), and economic freedom index. Both model specifications met several robustness checks, and showed overall significance and significant coefficients. Results showed that an increase in average sleep duration by 10 minutes is associated with an improvement in the happiness score by 0.1 and 0.15 points in the first and second model specifications respectively, noting an average happiness score of 6.2 in the country sample. The conclusion that sleep duration contributes to explaining variation in happiness levels across countries is a call for policy makers to consider policies targeting improvement in sleep adequacy as priority, and to direct more resources to further research in the area of sleep economics. Previous studies in the area of happiness economics did not consider sleep in explaining differences in happiness among countries, and previous studies in the area of economics of sleep did not consider the happiness index at a global level.

NREM sleep is the state of vigilance that best identifies the epileptogenic zone in the interictal electroencephalogram.

Interictal epileptiform anomalies such as epileptiform discharges or high-frequency oscillations show marked variations across the sleep-wake cycle. This study investigates which state of vigilance is the best to localize the epileptogenic zone (EZ) in interictal intracranial electroencephalography (EEG). Thirty patients with drug-resistant epilepsy undergoing stereo-EEG (SEEG)/sleep recording and subsequent open surgery were included; 13 patients (43.3%) had good surgical outcome (Engel class I). Sleep was scored following standard criteria. Multiple features based on the interictal EEG (interictal epileptiform discharges, high-frequency oscillations, univariate and bivariate features) were used to train a support vector machine (SVM) model to classify SEEG contacts placed in the EZ. The performance of the algorithm was evaluated by the mean area under the receiver-operating characteristic (ROC) curves (AUCs) and positive predictive values (PPVs) across 10-minute sections of wake, non-rapid eye movement sleep (NREM) stages N2 and N3, REM sleep, and their combination. Highest AUCs were achieved in NREM sleep stages N2 and N3 compared to wakefulness and REM (P<.01). There was no improvement when using a combination of all four states (P>.05); the best performing features in the combined state were selected from NREM sleep. There were differences between good (Engel I) and poor (Engel II-IV) outcomes in PPV (P<.05) and AUC (P<.01) across all states. The SVM multifeature approach outperformed spikes and high-frequency oscillations (P<.01) and resulted in results similar to those of the seizure-onset zone (SOZ; P>.05). Sleep improves the localization of the EZ with best identification obtained in NREM sleep stages N2 and N3. Results based on the multifeature classification in 10minutes of NREM sleep were not different from the results achieved by the SOZ based on 12.7days of seizure monitoring. This finding might ultimately result in a more time-efficient intracranial presurgical investigation of focal epilepsy.

Modeling the cardiometabolic benefits of sleep in older women: exploring the 24-hour day.

Activities throughout the day, including sleep, sedentary behavior (SB), light-intensity physical activity (LIPA), and moderate to vigorous physical activity (MVPA) are independently associated with cardiometabolic health. Few studies have examined interrelationships between sleep and 24-hour activity and associations with cardiometabolic risk. The objective of this study is to understand how replacing time in SB, LIPA, or MVPA with sleep impacts cardiometabolic risk. Women's Health Initiative OPACH Study participants (N = 3329; mean age = 78.5 ± 6) wore ActiGraph GT3X+ accelerometers 24 hours/7 days. Adjusted linear regression estimated the relationship between sleep duration and cardiometabolic markers. Separately for shorter (<8 hours) and longer (≥8 hours) sleepers, isotemporal substitution models estimated the cross-sectional associations with cardiometabolic markers with reallocating time in daytime activities to or from sleep. Longer sleep duration was associated with higher insulin, HOMA-IR, glucose, total cholesterol, and triglycerides (all p < 0.05). The associations between sleep duration and C-reactive protein, waist circumference, and body mass index (BMI) were U-shaped (both p < 0.05). For shorter sleepers, reallocating 33 minutes of MVPA to sleep was associated with higher values of insulin, HOMA-IR, glucose, triglycerides, waist circumference, and BMI (0.7%-11.5%). Replacing 91 minutes of SB time with sleep was associated with lower waist circumference and BMI (-1.3%, -1.8%). For long sleepers, shifting 91 minutes of sleep to SB was associated with higher waist circumference and BMI (1.3%, 1.4%). This is one of the first isotemporal analyses to include objectively measured sleep duration. Results illuminate possible cardiometabolic risks and benefits of reallocating time to or from sleep.

Linear and Nonlinear Associations between Sleep and Adjustment in Adolescence

ABSTRACT Background & Objectives A growing body of work supports linear associations between sleep and socioemotional adjustment in adolescence. However, associations between sleep and adjustment are not necessarily linear and investigations of nonlinear effects are scarce. This study examined linear and nonlinear relations between several sleep-wake parameters and externalizing behavior and internalizing symptoms in adolescence, and assessed the role of adolescent sex as a moderator of effects. Participants Participants were high school students (N = 180; M age = 17.49, SD = .62; 59% female; 68% White/European American, 32% Black/African American) from a wide range of socio-economic backgrounds living in semirural communities and small towns in Alabama. Methods Sleep-wake parameters were indexed by actigraphy-derived sleep minutes and adolescents’ reports on morningness-eveningness (circadian preference), sleep-wake problems (sleep quality), and sleepiness. Adolescents completed questionnaires on externalizing behaviors and internalizing symptoms. Results Controlling for sleep duration, a higher preference for eveningness and poor sleep quality were associated in a linear fashion with increased externalizing and internalizing symptoms. Nonlinear relations between sleepiness and internalizing symptoms emerged with pronounced sex-related effects, including somewhat delayed accelerating relations for males and rapidly accelerating associations that tended to plateau for females. Conclusions Results illustrate the importance of examining multiple sleep-wake and adjustment variables as well as linear and nonlinear associations.

Sleep and adjustment in adolescence: physical activity as a moderator of risk

ObjectivesWe investigated physical activity as a moderator of relations between sleep duration and quality and adolescents' internalizing and externalizing problems. DesignThe study used a cross-sectional design. SettingParticipants were recruited from small towns and semi-urban communities in Alabama. ParticipantsThe sample was comprised of 235 adolescents (Mage = 15.78 years, SD = 9.60 months) who were diverse in sex (53% female), race/ethnicity (34% Black/African American, 66% White), and socioeconomic status. MeasurementsSleep duration (actual sleep minutes), efficiency (minutes/total sleep period), and latency (minutes from sleep attempt to onset) were examined with actigraphs for 1 week. Youth reported on their physical activity levels and internalizing and externalizing problems. ResultsInteractions between sleep and physical activity emerged in the prediction of adolescents' internalizing and externalizing problems. Supportive of moderation effects, adolescents with shorter or poorer-quality sleep in conjunction with less physical activity showed the highest levels of internalizing and externalizing problems. Demonstrative of protective effects, adolescents with more physical activity had lower levels of internalizing and externalizing problems regardless of their sleep duration or quality. ConclusionsFindings illustrate that not all youth are at equal risk for adjustment problems when they experience short or poor-quality sleep, suggesting the importance of examining both bioregulatory and environmental factors in understanding adolescent adjustment.

The effects of intermittent light during the evening on sleepiness, sleep electroencephalographic spectral power and performance the next morning

Most studies on the effects of light exposure have been conducted with continuous light. The present study investigated the effects of intermittent light exposure on sleepiness, mood, electroencephalographic activity during sleep and performance the next morning. Fifteen volunteers were scheduled to come to the sleep laboratory to experience different lighting conditions: intermittent bright light, continuous bright light and continuous dim light. Subjective sleepiness and mood were assessed during light exposure, with electroencephalographic recording during sleep. After waking the next morning, participants filled out questionnaires and went through two cognitive tasks. The results revealed significantly lower ratings of sleepiness after intermittent light exposure, which is not different from the ratings in the continuous bright light condition, and an increase in vitality during later part of the evening and more beta activity during the first 90 minutes of sleep in the intermittent light condition, in comparison with the continuous dim light condition. However, both intermittent and continuous bright light exposure showed no difference from the continuous dim light condition in subjects' mood and cognitive functioning the next morning. The data indicated intermittent light during evening decreased sleepiness, had only minimal impact on mood in the evening, increased beta electroencephalographic activity during sleep, but had no significant influence on cognitive functioning the next morning.

SPORTS PERFORMANCE, SLEEP AND ANXIETY IN CHILDREN AND ADOLESCENTS: PRELIMINARY RESULTS OF A LONGITDUINAL STUDY

Background: There is limited literature and data on the longitudinal effects of sleep on the regular activities and experiences in which middle school and high school students participate. In the first year of this 6 year longitudinal study, we aim to look at the preliminary results of sleep, sports and anxiety with the graduating class of 2023. Methods: 48 seventh grade students were administered an ActiGraph watch to assess sleep patterns, movements, and activity levels. Students also completed a background questionnaire to obtain basic information such as extracurricular and physical participation and subjective reporting of past injuries. The Beck Youth Anxiety Inventory (BYAI) is a validated outcome questionnaire that was also administered to assess the students’ specific worries about school performance, the future, and fear. The BYAI scores are converted into a T-score that are compared to normative sample scores to determine the students’ relative deviation from the mean of the normative group. After wearing the ActiGraph watch for 5 school nights, data was reviewed with a board certified sleep pulmonologist and Total Sleep Time (TST) was recorded for each night. Results: 23 males and 25 females wore the watch for 5 school nights. Average age of students was 13 years (range: 12 to 13). During the study period, sleep, anxiety and sports participation were recorded . 240 school nights of nocturnal sleep were analyzed. TST averaged 6.5 hours (392 minutes). Females averaged 6.6 hours (395 minutes) of TST and males averaged 6.5 hours (391 minutes) of TST. For sports participation, both males and females played an average of 2 total organized sports during the course of the school year, not necessarily concurrently. On the BYAI, males had an average score of 13 and females had an average score of 12. Mild to moderate anxiety is represented by a score of 10-18. Students who played 1 sport or less (n=21) had an average TST of 6.5 hours (387 minutes) (335-440 minutes) and students who played more than 1 sport (n=27) had an average TST of 6.6 hours (396 minutes) (range: 323 to 463) (n=27). There was no significant difference between the two groups (p=0.37). There was a mild negative correlation between total number of sports played and the BYAI score in males (r= -0.31). Conclusion: These preliminary results stand as a baseline insight into students and their sleeping habits, activity levels, and overall emotional state. The National Sleep Foundation (NSF) recommends 9-11 hours (540-660 minutes) of sleep per night for children 6-13 years. The average sleep time of our student population is significantly below the recommendation of the NSF. The students who played more sports reported more sleep, though not at a significantly higher rate, and males who played fewer sports had a higher anxiety score. At this young age, students are in the early stages of learning their natural abilities in sports, creating skills to excel in academic and physical performance, and are starting to go through physical development and maturation. Students are still playing sports for enjoyment and reporting anxiety at a minimal level. Over the next 5 years, we hope to look at trends and identify internal and external factors that impact sleep, cognitive functioning, athletic performance and mental health.

Interactions between sleep duration and quality as predictors of adolescents' adjustment

ObjectivesWe examined interactions between adolescents' sleep duration and quality as predictors of their internalizing symptoms and externalizing behaviors. As a secondary aim, we assessed adolescent sex, race/ethnicity, and socioeconomic status (SES) as additional moderators of risk (ie, 3-way interactions among sleep duration; quality; and sex, race, or SES). DesignThe study used a cross-sectional design. SettingParticipants were from small towns and semirural communities in Alabama. ParticipantsThe sample consisted of 235 adolescents (Mage = 15.78 years, SD = 9.60 months) and was diverse with respect to sex (54% female), race/ethnicity (32% Black/African American, 67% White), and SES. MeasurementsSleep duration (actual sleep minutes) was examined with actigraphs for 1 week. Adolescents reported on their subjective sleep quality, internalizing symptoms, and externalizing behavior with psychometrically sound measures. ResultsFindings revealed interactions between sleep duration and sleep quality as predictors of adolescents' adjustment. Adolescents with both short sleep duration in conjunction with poor sleep quality had the highest levels of internalizing symptoms and aggressive and rule-breaking behavior. SES interacted with sleep duration and sleep quality to predict rule-breaking behavior, and the highest level of problems was observed for adolescents from lower-SES homes who had short sleep duration accompanied by poor sleep quality. ConclusionsFindings identify the conjoint role of sleep duration and quality as predictors of adolescents' socioemotional adjustment and emphasize the importance of examining multiple sleep parameters simultaneously toward a better understanding of adaptation in adolescence.

Apnea Hypopnea Index During Rapid Eye Movement Sleep With Diabetic Retinopathy in Patients With Type 2 Diabetes.

Recent studies based on home sleep apnea testing (HSAT) reported the potential association of sleep disordered breathing, such as obstructive sleep apnea (OSA), with diabetic retinopathy (DR). A few studies showed that the apnea-hypopnea index (AHI) during rapid eye movement (REM) sleep (REM-AHI) is associated with glycated hemoglobin and hypertension, two known risk factors for DR. However, there are no studies that have evaluated the association of REM-AHI with DR because previous studies were based on HSAT. To determine the association of REM-AHI with DR. The study subjects were 131 patients with type 2 diabetes mellitus who underwent all-night polysomnography with ≥30 minutes of REM sleep and were free of heart failure or active lung disease and had not yet been treated for OSA. Logistic regression analysis was performed to determine the effect of REM-AHI on the prevalence of DR adjusted by several known risk factors for DR. Quartile of REM-AHI was independently associated with DR (P = 0.024) (Q2: OR, 3.887; 95% CI, 0.737 to 20.495; Q3: OR, 9.467; 95% CI, 1.883 to 47.588; Q4: OR, 12.898; 95% CI, 2.008 to 82.823 relative to Q1), whereas quartile of non-REM (NREM)-AHI was not (P = 0.119). Similarly, continuous REM-AHI (OR, 2.875; 95% CI, 1.224 to 6.752; P = 0.015) was independently associated with DR, whereas NREM-AHI was not (P = 0.107). In addition, AHI was independently associated with DR when controlling for several known risk factors for DR (P = 0.043). REM-AHI was independently associated with DR. REM-AHI could be a potential risk factor for DR.

Cardiovascular Outcomes and All-Cause Mortality in Patients with Obstructive Sleep Apnea and Chronic Obstructive Pulmonary Disease (Overlap Syndrome).

The combined impact of chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea (OSA) on cardiovascular outcomes remains controversial. We determined whether the combined presence of COPD and severe OSA defined by the apnea-hypopnea index (AHI) or degree of nocturnal hypoxemia is associated with increased hazards of cardiovascular events and mortality. Prospectively collected data from adults with suspected OSA who underwent sleep study between 1994 and 2010 were linked to provincial administrative data to determine a presence of COPD and composite outcome. Exposures of interest were: 1) AHI greater than 30, and 2) 10 or more minutes of sleep time spent with oxygen saturation (SaO2) less than 90%. The primary outcome was a composite of hospitalization due to myocardial infarction, stroke, congestive heart failure, cardiac revascularization procedures, or death from any cause. Using Cox regression and controlling for confounders, hazards were compared between four groups: AHI greater than 30 with COPD, AHI greater than 30 without COPD, AHI less than or equal to 30 with COPD, and AHI less than or equal to 30 without COPD (reference). A similar approach was used for the degree of nocturnal hypoxemia. Relative excess risk due to interaction (RERI) was calculated. To adjust for the effect of positive airway pressure treatment, given that information on its acceptance, but not adherence, was available, a separate analysis was conducted only on untreated individuals who never claimed a positive airway pressure device. Among 10,149 participants, 30% had AHI greater than 30, 25% spent at least 10 minutes of sleep with SaO2 less than 90%, and 12% had COPD. Over a median of 9.4 years, 16.4% developed an outcome. In the total sample, a greater hazard of outcome was observed in individuals with COPD who spent at least 10 minutes of sleep with SaO2 less than 90% (hazard ratio, 1.91; 95% confidence interval [CI], 1.60 to 2.28) but not with AHI greater than 30; a synergistic effect was found in women (RERI, 1.18; 95% CI, 0.05 to 2.30), but not men (RERI, -0.08; 95% CI, -0.47 to 0.32). The highest hazard of outcome was associated with the co-occurrence of AHI greater than 30 and COPD in untreated individuals (hazard ratio, 2.01; 95% CI, 1.55 to 2.62); a synergistic effect was not found. In adults with suspected OSA, the co-occurrence of nocturnal hypoxemia and COPD was associated with an increased hazard of cardiovascular events and mortality with a synergistic effect found only in women.

Slow-wave activity surrounding stage N2 K-complexes and daytime function measured by psychomotor vigilance test in obstructive sleep apnea.

To better understand the inter-individual differences in neurobehavioral impairment in obstructive sleep apnea (OSA) and its treatment with continuous positive airway pressure (CPAP), we examined how changes in sleep electroencephalography (EEG) slow waves were associated with next-day psychomotor vigilance test (PVT) performance. Data from 28 OSA subjects (Apnea-Hypopnea Index with 3% desaturation and/or with an associated arousal [AHI3A] > 15/hour; AHI3A = sum of all apneas and hypopneas with 3% O2 desaturation and/or an EEG arousal, divided by total sleep time [TST]), who underwent three full in-lab nocturnal polysomnographies (NPSGs: chronic OSA, CPAP-treated OSA, and acute OSA), and 19 healthy sleepers were assessed. Four 20-minute PVTs were performed after each NPSG along with subjective and objective assessment of sleepiness. Three EEG metrics were calculated: K-complex (KC) Density (#/minute of N2 sleep), change in slow-wave activity in 1-second envelopes surrounding KCs (ΔSWAK), and relative frontal slow-wave activity during non-rapid eye movement (NREM) (%SWA). CPAP treatment of OSA resulted in a decrease in KC Density (chronic: 3.9 ± 2.2 vs. treated: 2.7 ± 1.1; p < 0.01; mean ± SD) and an increase in ΔSWAK (chronic: 2.6 ± 2.3 vs. treated: 4.1 ± 2.4; p < 0.01) and %SWA (chronic: 20.9 ± 8.8 vs. treated: 26.6 ± 8.6; p < 0.001). Cross-sectionally, lower ΔSWAK values were associated with higher PVT Lapses (chronic: rho = -0.55, p < 0.01; acute: rho = -0.46, p = 0.03). Longitudinally, improvement in PVT Lapses with CPAP was associated with an increase in ΔSWAK (chronic to treated: rho = -0.48, p = 0.02; acute to treated: rho = -0.5, p = 0.03). In contrast, OSA severity or global sleep quality metrics such as arousal index, NREM, REM, or TST were inconsistently associated with PVT Lapses. Changes in EEG slow waves, in particular ∆SWAK, explain inter-individual differences in PVT performance better than conventional NPSG metrics, suggesting that ΔSWAK is a night-time correlate of next-day vigilance in OSA.

Obstructive Sleep Apnea and Sleep Position: Does It Matter for Infants With a Cleft Palate?

To determine whether nonsupine sleep improves obstructive sleep apnea (OSA) in infants with cleft palate undergoing polysomnography (PSG). Retrospective chart review. Tertiary care pediatric hospital. Twenty-seven infants (1 month to 1 year) with cleft palate with or without cleft lip (CP ± L) undergoing PSG testing for suspected OSA were included. Polysomnography measures included obstructive apnea-hypopnea index (OAHI), central apnea-hypopnea index (CAHI), oxygen saturation (SpO2) nadir, SpO2, and end-tidal carbon dioxide (ETCO2). Twenty-three PSGs with at least 20 minutes of sleep in both the supine and the nonsupine positions were analyzed. The supine OAHI (mean: 16.8 events/hour; standard deviation [SD]: 18.5) and nonsupine OAHI (mean: 12.6 events/hour; SD: 12.6) did not differ significantly (P = .10). The supine CAHI (mean: 1.9 events/hour; SD: 2.7) and nonsupine CAHI (mean: 3.1 events/hour; SD: 3.7; P = .15), the supine SpO2 nadir (mean: 81.2%; SD: 6.3) and nonsupine SpO2 nadir (mean: 81.8%; SD: 5.3; P = .70), the supine mean SpO2 (mean: 95.5%; SD: 1.9) and nonsupine mean SpO2 saturation (mean: 95.3%; SD: 2.4; P = .34), and the supine ETCO2 (mean: 45.4 mm Hg; SD: 5.3) and nonsupine ETCO2 (mean: 42.5 mm Hg; SD: 10.1; P = .24) were also similar. There were no significant improvements in OSA metrics during nonsupine sleep in infants with CP ± L. Prior to recommending nonsupine positioning which increases infant's exposure to sudden infant death syndrome risk, we advocate obtaining a PSG to verify an objective improvement in OSA.

Polygenic risk score identifies associations between sleep duration and diseases determined from an electronic medical record biobank.

We aimed to detect cross-sectional phenotype and polygenic risk score (PRS) associations between sleep duration and prevalent diseases using the Partners Biobank, a hospital-based cohort study linking electronic medical records (EMR) with genetic information. Disease prevalence was determined from EMR, and sleep duration was self-reported. A PRS for sleep duration was derived using 78 previously associated SNPs from genome-wide association studies (GWAS) for self-reported sleep duration. We tested for associations between (1) self-reported sleep duration and 22 prevalent diseases (n = 30 251), (2) the PRS and self-reported sleep duration (n = 6903), and (3) the PRS and the 22 prevalent diseases (n = 16 033). For observed PRS-disease associations, we tested causality using two-sample Mendelian randomization (MR). In the age-, sex-, and race-adjusted model, U-shaped associations were observed for sleep duration and asthma, depression, hypertension, insomnia, obesity, obstructive sleep apnea, and type 2 diabetes, where both short and long sleepers had higher odds for these diseases than normal sleepers (p < 2.27 × 10-3). Next, we confirmed associations between the PRS and longer sleep duration (0.65 ± 0.19 SD minutes per effect allele; p = 7.32 × 10-04). The PRS collectively explained 1.4% of the phenotypic variance in sleep duration. After adjusting for age, sex, genotyping array, and principal components of ancestry, we observed that the PRS was also associated with congestive heart failure (CHF; p = 0.015), obesity (p = 0.019), hypertension (p = 0.039), restless legs syndrome (RLS; p = 0.041), and insomnia (p = 0.049). Associations were maintained following additional adjustment for obesity status, except for hypertension and insomnia. For all diseases, except RLS, carrying a higher genetic burden of the 78 sleep duration-increasing alleles (i.e. higher sleep duration PRS) associated with lower odds for prevalent disease. In MR, we estimated causal associations between genetically defined longer sleep duration with decreased risk of CHF (inverse variance weighted [IVW] OR per minute of sleep [95% CI] = 0.978 [0.961-0.996]; p = 0.019) and hypertension (IVW OR [95% CI] = 0.993 [0.986-1.000]; p = 0.049), and increased risk of RLS (IVW OR [95% CI] = 1.018 [1.000-1.036]; p = 0.045). By validating the PRS for sleep duration and identifying cross-phenotype associations, we lay the groundwork for future investigations on the intersection between sleep, genetics, clinical measures, and diseases using large EMR datasets.

Effects of Increased Pharyngeal Tissue Mass Due to Fluid Accumulation in the Neck on the Acoustic Features of Snoring Sounds in Men.

Snoring sounds are generated by the vibration of pharyngeal tissue due to the upper airway narrowing. While recorded by a microphone placed over the neck, snoring can pass through the pharyngeal tissue surrounding the upper airway. Thus, changes in the pharyngeal tissue content may change the acoustic properties of the snoring sounds. Rostral fluid shift and the consequent increases in neck fluid volume (NFV) and neck circumference (NC) can increase pharyngeal tissue mass. Therefore, the goal of this study was to investigate the relationship between increases in pharyngeal tissue mass, as assessed by increased NFV and NC, and snoring sounds features. We obtained data from a previous study where 20 males who were not obese participated in a daytime polysomnography and their NC and NFV were measured before and after sleep. During sleep, snoring sounds were recorded with a microphone placed over the neck. Spectral centroid of the snoring sounds was estimated. Then, the first five snoring segments were selected from the first and last 30 minutes of stage N2 sleep. We found a significant decrease in the snoring spectral centroid from the beginning to end of sleep. We also found that spectral centroid from the end of sleep in frequency ranges below 200 Hz was inversely correlated with the increases in NFV and NC from before to after sleep. These results suggest that snoring spectral centroid can be used as a noninvasive and convenient method to assess variations in the pharyngeal tissue mass.

Stability and change in daytime and nighttime sleep in children attending daycare

Many young children experience insufficient or poor quality sleep, which may have implications for adjustment and cognitive performance. This study tested group-level changes and rank-order stability in both daytime and nighttime sleep parameters over a six-month period, from fall to spring, among children receiving high-quality, center-based daycare. A total of 68 preschoolers (54% girls; Mage = 3.80 years, SD = .68) participated. Sleep was assessed via actigraphy for seven days and nights; sleep duration (actual sleep minutes) and quality parameters were derived. Analyses of group-level changes indicated that children’s daytime and nighttime sleep duration did not change significantly from fall to spring. Nighttime sleep quality showed significant improvement, however, such that children had higher sleep efficiency in the spring than in the fall. Rank-order stability in both nighttime and daytime measures of sleep duration and quality was moderate, and stability in daytime sleep quality was low. Results add to a sparse literature examining stability in sleep parameters in young children using actigraphy.

Assessing ventilatory instability using the response to spontaneous sighs during sleep in preterm infants.

Periodic breathing (PB) is common in newborns and is an obvious manifestation of ventilatory control instability. However, many infants without PB may still have important underlying ventilatory control instabilities that go unnoticed using standard clinical monitoring. Methods to detect infants with "subclinical" ventilatory control instability are therefore required. The current study aimed to assess the degree of ventilatory control instability using simple bedside recordings in preterm infants. Respiratory inductance plethysmography (RIP) recordings were analyzed from ~20 minutes of quiet sleep in 20 preterm infants at 36 weeks post-menstrual age (median [range]: 36 [34-40]). The percentage time spent in PB was also calculated for each infant (%PB). Spontaneous sighs were identified and breath-by-breath measurements of (uncalibrated) ventilation were derived from RIP traces. Loop gain (LG, a measure of ventilatory control instability) was calculated by fitting a simple ventilatory control model (gain, time-constant, delay) to the post-sigh ventilatory pattern. For comparison, periodic inter-breath variability was also quantified using power spectral analysis (ventilatory oscillation magnitude index [VOMI]). %PB was strongly associated with LG (r2 = 0.77, p < 0.001) and moderately with the VOMI (r2 = 0.21, p = 0.047). LG (0.52 ± 0.05 vs. 0.30 ± 0.03; p = 0.0025) and the VOMI (-8.2 ± 1.1 dB vs. -11.8 ± 0.9 dB; p = 0.026) were both significantly higher in infants that displayed PB vs. those without. LG and VOMI determined from the ventilatory responses to spontaneous sighs can provide a practical approach to assessing ventilatory control instability in preterm infants. Such simple techniques may help identify infants at particular risk for ventilatory instabilities with concomitant hypoxemia and its associated consequences.

Accuracy of Patient Perception of Supine Sleep.

For clinicians involved in investigating and treating sleep disorders, understanding the accuracy of patient recall of supine sleep would allow informed comparisons between polysomnography (PSG) and patient-reported sleep in patients with supine-predominant obstructive sleep apnea. This study aims to assess the accuracy of patient perception of supine sleep. Prospective observational cohort study, assessing patient perception of total sleep and supine sleep, including duration. Data were analyzed utilizing descriptive statistics, bias-plot (Bland-Altman) analysis, and Spearman correlation (rs) to analyze relationships among continuous data. Total number of patients who underwent PSG was 518, with data from 368 of these patients analyzed. Most of these patients underwent diagnostic PSG (49.2%). Patients were excluded because of missing or incomplete data (n = 133) or immobility (n = 17). Some patients (n = 97, 26%) did not perceive supine sleep, with 34 (35% of those with unperceived supine sleep or 9% of whole group) of these having more than 60 minutes of PSG supine sleep (range 0-305.5 minutes). All "unsure" patients (n = 8, 2.2%) had significant supine sleep recorded (31.5-257.5 minutes). For the presence of any PSG supine sleep, questioning had a sensitivity of 77.9%, specificity 72.7% with positive predictive value of 96.7% and negative predictive value of 24.5%. There was a significant correlation (rs = 0.63, P < .0001) between perceived and PSG supine sleep, but wide limits of agreement (-246.9 to 194.2 minutes). In patients undergoing in-laboratory PSG, the perception of supine sleep predicts the presence of PSG supine sleep. However, questioning patients has a poor negative predictive value and patient estimates of supine sleep duration are inaccurate.

Sleep and Exercise in Emergency Medicine Residents: An Observational Pilot Study Exploring the Utility of Wearable Activity Monitors for Monitoring Wellness.

IntroductionBurnout is well-documented in residents and emergency physicians. Wellness initiatives are becoming increasingly prevalent, but there is a lack of data supporting their efficacy. In some populations, a relationship between sleep, exercise, and wellness has been documented; however, this relationship has not been established in emergency medicine (EM) residents or physicians. We aim to determine whether a wearable activity monitor is a feasible method of evaluating exercise and sleep quality and quantity in emergency medicine residents and if these assessments are associated with greater perceived wellness.MethodsTwenty EM residents from two training sites wore a wearable activity monitor (Fitbit ChargeTM, Fitbit, Inc., San Francisco, CA, USA) during a four-week EM rotation. The Fitbit recorded data on sleep quantity (minutes sleeping) and quality (sleep disruptions), as well as exercise quantity and quality (daily step count, daily active minutes performing activity of 3 - 6, and > 6 metabolic equivalents). Participants completed an end-of-rotation Perceived Wellness Survey (PWS), which provided information on six domains of personal wellness (psychological, emotional, social, physical, spiritual, and intellectual). PWS levels were compared between groups of subjects with higher or lower levels of activity and sleep (i.e., above and below the median subject-averaged values) using the Mann-Whitney U test. Other subject characteristics were similarly assessed for their association with PWS. When a possible confounding effect was seen, the data was stratified and reviewed using a scatterplot.ResultsOf the 28 eligible residents, 23 agreed to participate. Of these, 20 and 16 wore the device for at least 50% of the respective days and nights during the observation period. Two devices were lost. One PWS was not completed. There was no statistically significant correlation between resident perceived wellness survey scores, sleep interruptions, average daily sleep minutes, daily step count, or average daily active minutes for the sample overall. However, first-year residents and residents from years two to five reported different median PWS scores of 13.9 and 17.1, respectively. Further exploration by the training group suggested that step counts may correlate with wellness in participants in their first year of residency, while the quantity of sleep may have an association with wellness in participants in years two through five of their residency.ConclusionUsing wearable activity monitor devices to capture sleep and exercise data among residents does not seem to be an effective approach. Our data does not support our hypothesis that overall resident wellness was associated with exercise and sleep quality and quantity as measured by such a device. These results are counterintuitive and may be complicated by several measurement-related limitations and the possibility that benefits depend on the stage of training.

Cognitive performance and self-reported sleepiness are modulated by time-of-day during a mountain ultramarathon

ABSTRACTNinety-two runners completed the study during a 168 km mountain ultramarathon (MUM). Sleepiness, self-reported sleep duration, and cognitive performance were assessed the day before the race and up to eight checkpoints during the race. Sleepiness was assessed using the Karolinska Sleepiness Scale. Cognitive performance was also assessed using the Digital Symbol Substitution Task (DSST). Runner reported 23.40 ± 22.20 minutes of sleep (mean ± SD) during the race (race time: 29.38 to 46.20 hours). Sleepiness and cognitive performance decrements increased across this race, and this was modulated by time-of-day with higher sleepiness and greater performance decrements occurring during the early morning hours. Runners who slept on the course prior to testing had poorer cognitive performance, which may suggest that naps on the course were taken due to extreme exertion. This study provides evidence that cognitive performance deficits and sleepiness in MUM are sensitive to time into race and time-of-day.

The unfinished journey with modafinil and discovery of a novel population of modafinil-immunoreactive neurons

Modafinil, a wake-promoting compound now used worldwide in sleep medicine, was initially regarded as a sedative compound because mice were so quiet with respect to locomotion after receiving it that this behavioral state was qualified as sedation. In the early 1980's when modafinil was first assessed by polysomnography in a cat in our laboratory, surprisingly, the cat spent the whole night awake without even one minute of sleep! This initial observation resulted subsequently in a series of basic and clinical studies in order to define the pharmacological profile of modafinil and its mode of action and, notably, to identify the brain targets by which modafinil acts to promote wakefulness. These studies were undertaken using pharmacologic approach coupled with the Cerveau isolé (brain transection) preparation, c-fos labelling and knockout mouse models. It was also in this context that we have developed a purified polyclonal antibody against modafinil. We expected that using immunohistochemistry with this antibody would allow us to localize the brain distribution of modafinil dosing. Surprisingly, we found discrete modafinil immunoreactive neuronal populations in several brain areas of modafinil-naive cats, rodents and humans. The most numerous and intensely labeled modafinil-immunoreactive neurons characterized by granular staining were found in the basal forebrain. They shared the regional location with cholinergic and aspartate-containing neurons but did not colocalize with them. In summary, we here present a newly identified neuronal population located in the basal forebrain that has never previously been published and suggests that these modafinil-immunoreactive neurons might be involved in forebrain functions such as sleep-wake control and cognition. This paper briefly reviews our journey with modafinil research and presents new unpublished experimental data.