The latest medical research on Sleep Medicine

The research magnet gathers the latest research from around the web, based on your specialty area. Below you will find a sample of some of the most recent articles from reputable medical journals about sleep medicine gathered by our medical AI research bot.

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Treatment usage patterns of oral appliances for obstructive sleep apnea over the first 60 days: a cluster analysis.

J Clin Sleep

Oral appliance (OA) therapy usage can be objectively measured through temperature-sensing data chips embedded in the appliance. Initial reports of group data for short-term treatment usage suggest good nightly hours of usage. However, individual variability in treatment usage patterns has not been assessed. We aimed to identify OA treatment usage subtypes in the first 60 days and the earliest predictors of these usage patterns.

OSA patients were recruited for a study of OA therapy with an embedded compliance chip (DentiTrac, Braebon, Canada). Fifty-eight participants with 60 days of downloadable treatment usage data (5-minute readings) were analyzed. A hierarchical cluster analysis was used to group participants with similar usage patterns. A random forest classification model was used to identify the minimum number of days to predict usage subtype.

Three user groups were identified and named "consistent users" (48.3%), "inconsistent users" (32.8%) and "non-users" (19.0%). The first twenty days provided optimal data to predict which treatment usage group a patient would belong to at 60-days (90% accuracy). The strongest predictors of user group were downloaded usage data; average wear time and number of days missed.

Granular analysis of OA usage data suggests the existence of treatment user subtypes (consistent, inconsistent and non-users). Our data suggest that 60-day usage patterns can be identified in the first twenty days of treatment using downloaded treatment usage data. Understanding initial treatment usage patterns provide an opportunity for early intervention to improve long-term usage and outcomes.

Mandibular advancement device as treatment trial for catathrenia (nocturnal groaning).

J Clin Sleep

Catathrenia is a rare disease, classified as isolated symptoms and normal variants under sleep-related breathing disorders in the International Classification of Sleep Disorders, third edition. Because of its rarity, the research on its pathogenesis and treatment is insufficient. This study aimed to evaluate whether the mandibular advancement device (MAD) could be considered an alternative treatment trial and if so, to explore factors predicting its effectiveness.

Thirty patients (12 males and 18 females, aged 16 to 67 years) with catathrenia participated in the study. They underwent standard clinical evaluation, questionnaires, physical examinations, craniofacial evaluations, video-polysomnography, and imaging of the upper airway before and after the insertion of the MAD. Groaning index (GI, groaning episodes per hour of sleep) and apnea-hypopnea index (AHI) were evaluated and anatomic factors predicting effectiveness were explored.

The sleep efficiency of most patients was higher than 80% and groaning was present throughout all stages of sleep. With the insertion of MAD, GI decreased significantly from 5.8 (2.7, 14.3) to 2.8 (1.3, 12.2) events/h (P = 0.014). Age had a negative effect on efficacy. Mandibular repositioning of MAD, especially the amount of vertical opening and changes of cross-sectional area of hypopharynx, was positively related with efficacy.

The MAD could be considered a possible treatment trial for those seeking treatment for groaning.

Registry: Chinese Clinical Trial Registry; Identifier: ChiCTR-COC-17013239; URL:

Real-time prediction of upcoming respiratory events via machine learning using snoring sound signal.

J Clin Sleep

The aim of the study was to inspect acoustic properties and sleep characteristics of pre-apneic snoring sound. The feasibility of forecasting upcoming respiratory events by snoring sound was also investigated.

Participants with habitual snoring or heavy breathing sound during sleep were recruited consecutively. Polysomnography was conducted and snoring related breathing sound was recorded simultaneously. Acoustic features and sleep features were extracted from 30-second samples and a machine learning algorithm was used to establish two prediction models.

A total of 74 eligible participants were included. Model 1 tested by five-fold cross validation achieved the accuracy of 0.92 and area under the curve of 0.94 for respiratory event prediction. model 2 with acoustic features and sleep information tested by Leave-One-Out cross validation had the accuracy of 0.78 and area under the curve of 0.80. Sleep position was found to be the most important amongst all sleep features contributing to the performance.

Pre-apneic sound presented unique acoustic characteristics and snoring related breathing sound could be deployed as a real-time apneic event predictor. The model combined with sleep information served as a promising tool for an early warning system to forecast apneic events.

High turnover of types III and VI collagen in progressive idiopathic pulmonary fibrosis.


Prediction of idiopathic pulmonary fibrosis (IPF) progression is vital for the choice and timing of treatment and patient follow-up. This could potentially be achieved by prognostic blood biomarkers of extracellular matrix (ECM) remodelling.

Neoepitope biomarkers of types III and VI collagen turnover (C3M, C6M, PRO-C3 and PRO-C6) were measured in 185 patients with newly diagnosed IPF. Disease severity at baseline and progression over 6 months was assessed by lung function tests and 6-min walk tests. All-cause mortality was assessed over a 3-year follow-up period.

High baseline levels of C3M, C6M, PRO-C3 and PRO-C6 were associated with more advanced disease at the time of diagnosis. Baseline levels of C6M and PRO-C3 were also associated with mortality over 3 years of follow-up (hazard ratio [HR]: 2.3, 95% CI: 1.3-3.9, p = 0.002 and HR: 1.8, 95% CI: 1.1-3.0, p = 0.03). Patients with several increased biomarkers at baseline, representing a high ECM remodelling phenotype, had more advanced disease at baseline, higher risk of progression or death at 6 months (OR: 1.4, 95% CI: 1.1-1.8, p = 0.002) and higher mortality over 3 years of follow-up (HR: 2.4, 95% CI: 1.3-4.5, p = 0.007).

Blood biomarkers of types III and VI collagen turnover, assessed at the time of diagnosis, are associated with several indices of disease severity, short-term progression and long-term mortality. These biomarkers can help to identify patients with a high ECM remodelling phenotype at high risk of disease progression and death.

Reduced exercise tolerance in mild chronic obstructive pulmonary disease: The contribution of combined abnormalities of diffusing capacity for carbon monoxide and ventilatory efficiency.


The combination of both reduced resting diffusing capacity of the lung for carbon monoxide (DLCO ) and ventilatory efficiency (increased ventilatory requirement for CO2 clearance [V˙E /V˙CO2 ]) has been linked to exertional dyspnoea and exercise intolerance in chronic obstructive pulmonary disease (COPD) but the underlying mechanisms are poorly understood. The current study examined if low resting DLCO and higher exercise ventilatory requirements were associated with earlier critical dynamic mechanical constraints, dyspnoea and exercise limitation in patients with mild COPD.

In this retrospective analysis, we compared V˙E /V˙CO2 , dynamic inspiratory reserve volume (IRV), dyspnoea and exercise capacity in groups of patients with Global Initiative for Chronic Obstructive Lung Disease stage 1 COPD with (1) a resting DLCO at or greater than the lower limit of normal (≥LLN; Global Lung Function Initiative reference equations [n = 44]) or (2) below the <LLN (n = 33), and age- and sex-matched healthy controls (n = 81).

Spirometry and resting lung volumes were similar in the two COPD groups. During exercise, V˙E /V˙CO2 (nadir and slope) was consistently higher in the DLCO  < LLN compared with the other groups (all p < 0.05). The DLCO  < LLN group had lower IRV and greater dyspnoea intensity at standardized submaximal work rates and lower peak work rate and oxygen uptake than the other two groups (all p < 0.05).

Reduced exercise capacity in patients with DLCO  < LLN was related to higher ventilatory requirements, a faster rate of decline in dynamic IRV and greater dyspnoea during exercise. These simple measurements should be considered for the clinical evaluation of unexplained exercise intolerance in individuals with ostensibly mild COPD.

Structural and functional changes in COPD: What we have learned from imaging.


Chronic obstructive pulmonary disease (COPD) is the third leading cause of mortality worldwide. It is a heterogeneous disease involving different c...

Pharmacological treatment of stable chronic obstructive pulmonary disease.


Pharmacological treatment for chronic obstructive pulmonary disease (COPD) aims to alleviate symptoms and reduce the future risk of events such as ...

Circulating regulators of the wingless pathway in precapillary pulmonary hypertension.


Dysregulated Wnt signalling has been implicated in pulmonary hypertension (PH). We hypothesized that plasma levels of secreted Wnt proteins would be increased in patients with precapillary PH, correlate with indices of vascular resistance and cardiac function and give information on long-term prognosis.

We measured the Wnt ligand Wnt5a and secreted Wnt antagonists Dickkopf (DKK) DKK1, DKK3, secreted frizzled-related protein 3 (sFRP3), Wnt inhibitory factor-1 (WIF1) and sclerostin (SOST) in 106 patients with precapillary PH and 40 healthy controls. A second sample was obtained after a median of 4 months (n = 52). During a median of 90 months follow-up, 67 patients died.

Our main findings were (i) Precapillary PH is characterized by enhanced systemic Wnt activity as reflected by elevated plasma levels of Wnt5a and secreted antagonists irrespective of diagnostic subgroups. (ii) WIF1 and in particular Wnt5a correlated with pulmonary vascular resistance and cardiac dysfunction. (iii) High levels of Wnt5a, sFRP3, DKK3 and WIF1 were associated with poor prognosis in age- and sex-adjusted analysis (hazard ratios per log/SD change ~1.4) and for DKK3 after further adjustment with right arterial pressure, pulmonary oxygen saturation, cardiac index, N-terminal pro B-type natriuretic peptide and peak oxygen uptake (VO2 ). Finally, an elevation of Wnt5a and DKK3 during follow-up was independently associated with poor prognosis.

Our data indicate that Wnt signalling pathways could be implicated in the pathogenesis of precapillary PH, and that some of the Wnt-related molecules (i.e., Wnt5a and DKK3) should be further investigated in these patients.

Longitudinal monitoring of asthma in the clinic using respiratory oscillometry.


Asthma guidelines emphasize the importance of assessing lung function and symptoms. The forced oscillation technique (FOT) and its longitudinal relationship with spirometry and symptoms are unresolved. We examined concordance between longitudinal spirometry, FOT and symptom control, and determined FOT limits of agreement in stable asthma.

Over a 3-year period, adults with asthma attending a tertiary clinic completed the asthma control test (ACT), fraction of exhaled nitric oxide (FeNO), FOT and spirometry. Analysis included between-visit concordance for significant change using Cohen's kappa (κ) and stable asthma FOT limits of agreement.

Data (n = 186) from 855 visits (mean ± SD 4.6 ± 3.0 visits), 114 ± 95 days apart, were analysed. Between-visit concordance was moderate between reactance at 5 Hz (X5) and forced expiratory volume in 1 s (FEV1 ) (κ = 0.34, p = 0.001), and weak between ACT and FEV1 (κ = 0.18, p = 0.001). Change in FeNO did not correlate with lung function or ACT (κ < 0.05, p > 0.1). Stable asthma between visits (n = 75; 132 visits) had reduced lung function variability, but comparable concordance to the entire cohort. Limits of agreement for FEV1 (0.42 L), resistance at 5 Hz (2.06 cm H2 O s L-1 ) and X5 (2.75 cm H2 O s L-1 ) in stable asthma were at least twofold greater than published values in health.

In adults with asthma, there is moderate concordance between longitudinal change in FOT and spirometry. Both tests relate poorly to changes in asthma control, highlighting the need for multi-modal assessment in asthma rather than symptoms alone. The derivation of longitudinal FOT limits of agreement will assist in its clinical interpretation.

Sleep deprivation therapy to reset the circadian pacemaker in a non-24-hour sleep-wake disorder: a case report.

J Clin Sleep

Non-24-hour sleep-wake disorder (N24SWD) is one of several chronic circadian rhythm sleep-wake disorders (CRSWDs). It is defined as progressive dai...

The impact of lockdown on sleep patterns of children and adolescents with ADHD.

J Clin Sleep

The current study examined the impact of home confinement (lockdown) due to the COVID-19 pandemic on sleep patterns of children and adolescents with ADHD.

Nine hundred ninety-two parents of children and adolescents with ADHD filled out an anonymous online survey through the ADHD family association website. The survey investigated the sleep patterns and disturbances (using a modified version of the Sleep Disturbance Scale for Children) and screen exposure time before and during the lockdown.

During the lockdown, 59.3% of children and 69.4% of adolescents with ADHD reported a change of bedtime with significant increase of ADHD patients that went to sleep at 11pm or later. Sleep duration, in contrast, resulted in two opposing processes with more children and adolescent sleeping either less than 6 hours/night or 10-11 hours/night. Among children and adolescents, respectively, 19.9% and 22% slept less than they did before lockdown, while 21.4% and 27.4% slept more hours. Bedtime delay and decreased sleep duration were associated with an increase in the screen time exposure. Moreover, ADHD patients reported an increase in sleep disturbances when compared to previous condition, including mainly difficulties falling asleep, anxiety at bedtime, night awakenings, nightmares and daytime sleepiness.

The lockdown impacted on sleep-wake rhythms by strengthening the maladaptive sleep patterns reported in usual life conditions in ADHD children.

Effect of surgical intervention for mild childhood obstructive sleep apnoea on attention and behavioural outcomes: A randomized controlled study.


We evaluated inattention and behavioural outcomes following surgery versus watchful waiting (WW) in school-aged children with mild obstructive sleep apnoea (OSA).

A prospective randomized controlled study was performed in pre-pubertal children aged 6-11 years with polysomnography (PSG)-confirmed mild OSA. They were assigned randomly to early surgical intervention (ES) or WW. The surgical intervention consisting of tonsillectomy with or without adenoidectomy and turbinate reduction was carried out within 4-6 weeks after randomization. Both groups underwent PSG, attention and behavioural assessment and review by an otorhinolaryngologist at baseline and 9-month follow-up. The primary outcome was omission T score from Conners' continuous performance test (CPT). Secondary outcomes were parent-reported behaviours, quality of life, symptoms and PSG parameters.

A total of 114 participants were randomized. Data of 35 subjects from the ES and 36 from the WW group were available for final analysis. No significant treatment effect could be found in all CPT parameters and behavioural outcomes. Nevertheless, significantly greater reductions were seen in PSG parameters (obstructive apnoea-hypopnoea index [-1.4 ± 2.0 cf. +0.3 ± 4.1/h, p = 0.038] and arousal index [-1.3 ± 4.4 cf. +1.4 ± 4.5/h, p = 0.013]) and OSA-18 total symptom score (-17.3 ± 19.7 cf. -3.6 ± 14.1, p = 0.001) in the ES group. Subjects who underwent surgery also had significantly greater weight gain (+3.3 ± 2.1 cf. +2.2 ± 1.5 kg, p = 0.014) and increase in systolic blood pressure (+5.1 ± 12.4 cf. -1.2 ± 8.7 mm Hg, p = 0.016).

Despite improvements in PSG parameters and parent-reported symptoms, surgical treatment did not lead to parallel improvements in objective attention measures in school-aged children with mild OSA.