Somatic arousal and sleepiness/fatigue among patients with sleep-disordered breathing

Sleep disorder and apnea events detection framework with high performance using two-tier learning model design

Sleep apnea is defined as a breathing disorder that affects sleep. Early detection of sleep apnea helps doctors to take intervention for patients to prevent sleep apnea. Manually making this determination is a time-consuming and subjectivity problem. Therefore, many different methods based on polysomnography (PSG) have been proposed and applied to detect this disorder. In this study, a unique two-layer method is proposed, in which there are four different deep learning models in the deep neural network (DNN), gated recurrent unit (GRU), recurrent neural network (RNN), RNN-based-long term short term memory (LSTM) architecture in the first layer, and a machine learning-based meta-learner (decision-layer) in the second layer. The strategy of making a preliminary decision in the first layer and verifying/correcting the results in the second layer is adopted. In the training of this architecture, a vector consisting of 23 features consisting of snore, oxygen saturation, arousal and sleep score data is used together with PSG data. A dataset consisting of 50 patients, both children and adults, is prepared. A number of pre-processing and under-sampling applications have been made to eliminate the problem of unbalanced classes. Proposed method has an accuracy of 95.74% and 99.4% in accuracy of apnea detection (apnea, hypopnea and normal) and apnea types detection (central, mixed and obstructive), respectively. Experimental results demonstrate that patient-independent consistent results can be produced with high accuracy. This robust model can be considered as a system that will help in the decisions of sleep clinics where it is expected to detect sleep disorders in detail with high performance.

Symptoms of sleep disordered breathing: Association with the apnea-hypopnea index and somatic arousal

We investigated the association of typical symptoms of obstructive sleep apnea with a measure of daytime somatic arousal and with the apnea-hypopnea index. We extended the finding of an association between sleepiness, fatigue and somatic arousal previously reported in a US sleep apnea population to a German sleep apnea population (n = 374) and to other typical sleep apnea symptoms, insomnia, anxiety, daytime alertness and non-restorative sleep. Somatic arousal was measured using the body sensation questionnaire (BSQ). Correlations of apnea-hypopnea index and BSQ were computed with values of polysomnographic variables derived from overnight sleep studies and with severity of OSA symptoms. Apnea-hypopnea index and BSQ scores showed only a small negative correlation with each other; each correlated independently with the Epworth Sleepiness Scale score. Controlling for BSQ score, the apnea-hypopnea index was found to affect sleepiness only when it exceeded 50/h. Severity of all other sleep apnea symptoms did not increase with increasing apnea-hypopnea index. In contrast, severity of all symptoms of sleep apnea increased consistently with increasing BSQ scores. Thus, autonomic stress associated with obstructive sleep apnea may be the driving force behind sleep apnea symptoms rather than the sleep fragmentation associated with obstructive sleep apnea severity (apnea-hypopnea index). These findings support previously reported correlations by Gold and associates between the levels of somatic arousal, sleepiness and fatigue. Using the apnea-hypopnea index and BSQ together renders a more comprehensive assessment of sleep apnea than apnea-hypopnea index alone, which appears to impact only on sleepiness and only when it exceeds 50/h. More work is needed to elucidate the source of the chronic stress, which appears to arise endogenously in affected individuals, likely as a function of sleep disordered breathing, such as snoring/inspiratory flow limitation.

Intermittent Hypoxia Activates N-Methyl-D-Aspartate Receptors to Induce Anxiety Behaviors in a Mouse Model of Sleep-Associated Apnea

Sleep apnea disrupts physiologic homeostasis and causes neuronal dysfunction. In addition to signs of mental disorders and cognitive dysfunction, patients with sleep apnea have a higher anxiety rate. Here, we examined the mechanisms underlying this critical health issue. We used a mouse model with sleep-associated chronic intermittent hypoxia (IH) to verify the effects of sleep apnea on neuronal dysfunction. To evaluate how IH alters neuronal function to yield anxiety-like behavior and cognitive dysfunction, we examined synaptic plasticity and neuronal inflammation in related brain areas, including the medial prefrontal cortex (mPFC), striatum, and hippocampus. Mice subjected to chronic IH for 10 days exhibited significant anxiety-like behaviors in the elevated plus maze test. IH mice spent less travel time in open arms and more travel time in enclosed arms compared to control mice. However, cognitive impairment was minimal in IH mice. Increased glutamate N-methyl-D-aspartate (NMDA) receptor subunits 2B (GluN2B) and phosphorylated-ERK1/2 were seen in the mPFC, striatum, and hippocampus of IH mice, but no significant microglial and astrocyte activation was found in these brain areas. Chronic IH in mice induced compensatory increases in GluN2B to disturb neuronal synaptic plasticity, without neuronal inflammation. The altered synaptic plasticity subsequently led to anxiety-like behavior in mice. Treatment with the NMDA receptor antagonist dextromethorphan attenuated chronic IH-induced anxiety-like behavior and GluN2B expression. Our findings provide mechanistic evidence of how IH may provoke anxiety and support for the importance of early intervention to alleviate anxiety-associated complications in patients with chronic sleep apnea.

Chronic insomnia remitting after maxillomandibular advancement for mild obstructive sleep apnea: a case series

Background

Chronic insomnia and obstructive sleep apnea are both common sleep disorders. Chronic insomnia is thought to result from stress-related physiologic hyperarousal (somatic arousal) that makes it difficult for an individual to fall or stay asleep. Obstructive sleep apnea is thought to result from obstructive respiratory events causing arousals, sleep fragmentation, and recurrent oxygen desaturation. Although the two disorders seem different, they predispose to the same long-term, stress-related illnesses, and when they occur in the same individual, each affects the other’s response to treatment; they interact. This report of three cases describes patients with both chronic insomnia and obstructive sleep apnea in whom the chronic insomnia remitted with no specific treatment following treatment of obstructive sleep apnea with maxillomandibular advancement.

Case presentations

Our three Caucasians patients each presented with severe, chronic insomnia associated with somatic arousal and fatigue occurring either alone, in association with bipolar disorder, or with temporomandibular joint syndrome. Polysomnography revealed that each patient also had mild obstructive sleep apnea, despite only one snoring audibly. One patient experienced a modest improvement in her somatic arousal, insomnia severity, and fatigue with autotitrating nasal continuous positive airway pressure, but the other two did not tolerate nasal continuous positive airway pressure. None of the patients received treatment for insomnia. All three patients subsequently underwent maxillomandibular advancement to treat mild obstructive sleep apnea and experienced prolonged, complete resolution of somatic arousal, chronic insomnia, and fatigue. The patient with bipolar disorder also experienced complete remission of his symptoms of depression during the 1 year he was followed postoperatively.

Conclusions

These three cases lend support to the hypothesis that chronic insomnia and obstructive sleep apnea share a pathophysiology of chronic stress. Among patients with obstructive sleep apnea, the stress response is directed at inspiratory airflow limitation during sleep (hypopnea, snoring, and inaudible fluttering of the throat). Therefore, when chronic insomnia and obstructive sleep apnea occur in one individual, aggressive treatment of obstructive sleep apnea may lead to a reduction in chronic stress that causes the patient’s chronic insomnia to remit.

Pathologic and hemodynamic changes of common carotid artery in obstructive sleep apnea hypopnea syndrome in a porcine model

Background/aim

To prepare a porcine model of obstructive sleep apnea-hypopnea syndrome (OSAHS) and observe the pathological and hemodynamic changes in the common carotid artery.

Materials and methods

Twelve male miniature pigs were randomly divided into the model and control group (n = 6). Pigs in the model group were kept in an air-flow negative pressure chamber at 0.96 ± 0.01 kPa, and the air oxygen content, temperature, and humidity were kept at normal culture conditions in both groups. After pigs in the model group presented symptoms of OSAHS, changes in the hemodynamics and morphology of the carotid artery were analyzed using color Doppler, and light and electron microscopy.

Results

An animal model of OSAHS was successfully created. The internal diameter of the carotid artery of pigs in the model group was decreased, while the intima thickness, peak-systolic mean velocity, and resistance index were increased when compared to the control group (P < 0.05). The results of the light and electron microscopy revealed an incomplete elastic plate, increased media thickness, irregular morphology of the smooth muscle cells, increased collagen fiber bundles, partially disordered elastic fibers, and smooth muscle layers. The quantitative analysis showed significantly increased elastic fibers in the media of the carotid artery in the model group (P < 0.01).

Conclusion

Pathological changes in the tissue structure and hemodynamics in the negative pressure-induced pig OSAHS model were observed. We suggest that alterations in the upper airway pressure during OSAHS may lead to cardiovascular conditions through its pathological effects on the carotid artery.

Prevalence and Clinical Significance of Respiratory Effort-Related Arousals in the General Population

STUDY OBJECTIVES

To determine the prevalence and clinical associations of respiratory effort-related arousals (RERA) in a general population sample.

METHODS

A total of 2,162 participants (51.2% women, 58.5 ± 11.0 years old, body mass index [BMI] 25.6 ± 4.2 kg/m²) of a general population-based cohort (HypnoLaus, Switzerland) underwent full polysomnography at home. Each subject with a RERA index ≥ 5 events/h was compared with an age-, sex- and apnea-hypopnea index (AHI)-matched control without RERA.

RESULTS

A RERA index ≥ 5 events/h was present in 84 participants (3.8%; 95% confidence interval: 3.2-4.8%). In 17 participants (0.8%; 95% confidence interval: 0.5-1.3%), RERAs were the predominant sleep breathing disorder and only one of them complained of excessive daytime sleepiness. Compared to matched controls, subjects with a RERA index ≥ 5 events/h were similar in terms of BMI (26.5 ± 3.5 versus 26.3 ± 4.8 kg/m², P = .73), neck circumference (38.5 ± 3.3 versus 37.6 ± 3.7 cm, P = .10) and Epworth Sleepiness Scale score (6.7 ± 3.7 versus 6.0 ± 3.7, P = .22). Also, no differences were found for hypertension (21.4% versus 27.4%, P = .47), diabetes (7.1% versus 7.1%, P = 1.00), or metabolic syndrome (31.0% versus 23.8%, P = .39).

CONCLUSIONS

In a middle-aged population-based cohort, the prevalence of a RERA index ≥ 5 events/h was low (3.8%) and was not associated with negative clinical outcomes when using the currently recommended scoring criteria of the American Academy of Sleep Medicine.

Relationships between obstructive sleep apnea and anxiety

PURPOSE OF REVIEW

To summarize recent research investigating the interaction between obstructive sleep apnea (OSA) and anxiety, and contextualize their bidirectional relationship.

RECENT FINDINGS

Recent investigations corroborate the bidirectional relationship between sleep-disordered breathing (SDB) and anxiety, evaluate the etiological and clinical manifestations through different mechanisms, and provide insight into clinical implications of this interaction. Much of the literature about anxiety as it relates to SDB is from small samples, using different tools of symptom measurement that are often subjectively quantified. The objective severity of OSA does not appear to be associated with subjectively reported sleepiness and fatigue, whereas physiological manifestations of anxiety are associated with the severity of subjective symptoms reported. Recent findings support that women are more likely to have comorbid SDB and anxiety than men. SDB may precipitate and perpetuate anxiety, whereas anxiety in OSA negatively impacts quality-of-life. Treating SDB may improve anxiety symptoms, whereas anxiety symptoms can be an obstacle and deterrent to appropriate treatment.

SUMMARY

The interaction between anxiety and SDB is still poorly elucidated. Being aware of the clinical associations, risk factors, and treatment implications for SDB as related to anxiety disorders in different populations can help clinicians with the diagnosis and management of both SDB and anxiety.

Comorbid Insomnia With Obstructive Sleep Apnea: Clinical Characteristics and Risk Factors

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) and chronic insomnia are two common sleep disorders and both are considered independent risk factors for heart disease. The aim of this study was to investigate the prevalence of comorbid insomnia with OSA and to compare its clinical characteristics with those of OSA without insomnia.

METHODS

Patients who visited two tertiary university hospital sleep centers were screened. Those with a diagnosis of OSA using polysomnography were divided into two groups based on their scores on the Korean version of the Insomnia Severity Index (ISI-K): OSA with insomnia (OSA+I) (ISI-K score ≥ 15) and OSA without insomnia (OSA-I) (ISI-K score < 15). Subjective symptoms were evaluated using sleep questionnaires including ISI-K. Demographic and clinical characteristics of OSA+I and OSA-I were compared.

RESULTS

Out of 476 patients with OSA, 139 (29.2%) had significant insomnia. Patients in the OSA+I group had a higher percentage of females (35.3% versus 19.6%, P < .001) and have higher rates of heart disease (19.4% versus 8.6%, P < .001). OSA+I group showed lower quality of life, lower quality of sleep, higher sleep propensity, and higher depression as measured by the Korean versions of the Short-Form 36-Item Health Survey, Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, and Beck Depression Inventory, respectively. There were no significant differences in adherence to continuous positive airway pressure between the groups.

CONCLUSIONS

There is a high prevalence of comorbid insomnia with OSA (29.2%), consistent with previous findings in Western studies. Comorbid insomnia with OSA may constitute a cumulative risk factor for cardiovascular disease. These findings warrant further investigation into the mechanisms involved in its pathogenesis and devising more efficient treatments.

Long-Term Oral Appliance Therapy Improves Daytime Function and Mood in Upper Airway Resistance Syndrome Patients

Objectives

To evaluate the long-term effects of an oral appliance on clinical symptoms, respiratory sleep parameters, sleep quality, and sustained attention in patients with upper airway resistance syndrome (UARS) were compared with placebo.

Methods

This study was a randomized placebo-controlled clinical trial. Thirty UARS patients were randomized in two groups: placebo and mandibular advancement device (MAD) groups. UARS criteria were presence of sleepiness (Epworth Sleepiness Scale ≥ 10) and/or fatigue (Modified Fatigue Impact Scale ≥ 38) associated with an apnea/hypopnea index ≤ 5 and a respiratory disturbance index (RDI) > 5 events/hour of sleep, and/or flow limitation in more than 30% of total sleep time. All patients completed the Pittsburgh Sleep Quality Index (PSQI), the Functional Outcomes of Sleep Questionnaire, the Beck Anxiety and Depression Inventories, underwent full-night polysomnography, multiple sleep latency test, and Psychomotor Vigilance Test (PVT). Evaluations were performed before and after 1.5 years of treatment.

Results

RDI, number of respiratory effort-related arousal, percentage of total sleep time with flow limitation, and arousal index significantly decreased after 1.5 years of MAD treatment. PSQI total score improved, severity of depression symptoms decreased, and mean reaction time in the PVT, based on the first measurement taken at 8:00 am, significantly decreased (p = .03) at the end of the protocol.

Conclusions

The MAD was effective in decreasing respiratory events in UARS patients. For UARS, 1.5 years of oral appliance therapy also improved sleep quality and sustained attention, and decreased the severity of depression symptoms.

Clinical Trial

Efficacy of Oral Appliance for Upper Airway Resistance Syndrome: Randomized, Parallel, Placebo-Controlled Study, NCT02636621.

Somatic syndromes, insomnia, anxiety, and stress among sleep disordered breathing patients

OBJECTIVES

We tested the hypothesis that the prevalence of somatic syndromes, anxiety, and insomnia among sleep disordered breathing (SDB) patients is correlated with their levels of somatic arousal, the symptoms of increased sympathetic nervous system tone under conditions of stress.

METHODS

We administered the Body Sensation Questionnaire (BSQ; a 17-item questionnaire with increasing levels of somatic arousal scored 17-85) to 152 consecutive upper airway resistance syndrome (UARS) patients and 150 consecutive obstructive sleep apnea/hypopnea (OSA/H) patients. From medical records, we characterized each patient in terms of the presence of syndromes and symptoms into three categories: somatic syndromes (six syndromes), anxiety (anxiety disorders, nightmares, use of benzodiazepines), and insomnia (sleep onset, sleep maintenance, and use of hypnotics). For the pooled sample of SDB patients, we modeled the correlation of the BSQ score with the presence of each syndrome/symptom parameter within each of the three categories, with adjustment for male vs. female.

RESULTS

Mean BSQ scores in females were significantly higher than those in males (32.5 ± 11.1 vs. 26.9 ± 8.2; mean ± SD). Increasing BSQ scores significantly correlated with increasing prevalence rates of somatic syndromes (p < 0.0001), of anxiety (p < 0.0001), and of insomnia (p ≤ 0.0001). In general, females had higher prevalence rates of somatic syndromes and symptoms of anxiety than males at any BSQ score while rates of insomnia were similar.

CONCLUSIONS

In patients with SDB, there is a strong association between the level of somatic arousal and the presence of stress-related disorders like somatic syndromes, anxiety, and insomnia.