Association of insomnia phenotypes based on polysomnography-measured sleep duration with suicidal ideation and attempts

Mild-to-moderate obstructive sleep apnea and mortality risk in a general population sample: The modifying effect of age and cardiovascular/cerebrovascular comorbidity

About 5.4%-45.7% of the general population has mild-to-moderate obstructive sleep apnea (mmOSA), which is highly comorbid with cardiovascular and/or cerebrovascular diseases (CBVD). We examined the association between mmOSA and all-cause mortality and the modifying effect of age and CBVD. A total of 1681 adults 20-88 years old from the Penn State Adult Cohort (PSAC) (41.9% male) were followed up for 20.1 ± 6.2 years for all-cause mortality. Mild and moderate OSA were defined as an apnea/hypopnea index (AHI) 5-14.9 and 15-29.9 events/hour, respectively. CBVD was defined as a report of a physician diagnosis or treatment for heart disease and/or stroke. Cox proportional hazards regression models were used to estimate all-cause mortality adjusted for confounders. All-cause mortality risk was significantly increased in the mmOSA group in young and middle-aged adults (<60 years) (HR = 1.59, 95%CI 1.08-2.04) but not in older adults (≥60 years) (HR = 1.05, 95%CI 0.80-1.39). A synergistic effect between mmOSA and CBVD was stronger in those <60 years (HR = 3.82, 95%CI 2.25-6.48 in <60 years vs 1.86 95%CI 1.14-3.04 in ≥60 years). There was an additive effect between moderate OSA and hypertension in <60 but not in those ≥60 years. Mild OSA was associated with all-cause mortality only in the presence of CBVD. Mortality risk is increased in young and middle-aged adults with moderate OSA, whereas the mortality risk associated with mild OSA is elevated only, regardless of age, in the presence of comorbid CBVD. AHI cut-offs warranting treatment of mmOSA may need to be adjusted based on age and comorbidities.

Edward O. Bixler, PhD: from the Apollo project and chimpanzees to sleep epidemiology

What an honor to write about Dr. Edward O. Bixler's contributions to the sleep field. In 1967, Dr. Bixler published a case report on a chimpanzee with implanted brain electrodes while working at an Air Force base in New Mexico. A few years later, in 1971, he published on the sleep effects of flurazepam in individuals with insomnia together with Dr. Anthony Kales, data that he had collected when the Sleep Research & Treatment Center (SRTC) was housed at the University of California Los Angeles. Dr. Bixler, a meticulous scientist, learned from Dr. Kales, a devoted clinician, to study "the whole patient, and all aspects of sleep," a legacy that continued when the SRTC moved to Penn State in Hershey. Indeed, Dr. Bixler's tenure at Penn State from 1971 until 2019 kept the science of the SRTC focused on that premise and helped translate scientific evidence into clinical care. He not only contributed early to the pharmacology of sleep and the effects of hypnotics, but he was also a pioneer in "sleep epidemiology." His "Prevalence of sleep disorders in the Los Angeles metropolitan area" study of 1979 was the first rigorous epidemiological study on sleep disturbances. Starting in 1990, he established the Penn State Adult Cohort to estimate the prevalence and natural history of sleep-disordered breathing and other sleep disorders in adults. Inspired by life-course epidemiology, he established in 2001 the Penn State Child Cohort to estimate the same phenomena in children. This Living Legend paper captures and highlights Dr. Bixler's enduring legacy to sleep science.

Insomnia nosology: a systematic review and critical appraisal of historical diagnostic categories and current phenotypes

Insomnia nosology has significantly evolved since the Diagnostic and Statistical Manual (DSM)-III-R first distinguished between 'primary' and 'secondary' insomnia. Prior International Classification of Sleep Disorders (ICSD) nosology 'split' diagnostic phenotypes to address insomnia's heterogeneity and the DSM nosology 'lumped' them into primary insomnia, while both systems assumed causality for insomnia secondary to health conditions. In this systematic review, we discuss the historical phenotypes in prior insomnia nosology, present findings for currently proposed insomnia phenotypes based on more robust approaches, and critically appraise the most relevant ones. Electronic databases PsychINFO, PubMED, Web of Science, and references of eligible articles, were accessed to find diagnostic manuals, literature on insomnia phenotypes, including systematic reviews or meta-analysis, and assessments of the reliability or validity of insomnia diagnoses, identifying 184 articles. The data show that previous insomnia diagnoses lacked reliability and validity, leading current DSM-5-TR and ICSD-3 nosology to 'lump' phenotypes into a single diagnosis comorbid with health conditions. However, at least two new, robust insomnia phenotyping approaches were identified. One approach is multidimensional-multimethod and provides evidence for self-reported insomnia with objective short versus normal sleep duration linked to clinically relevant outcomes, while the other is multidimensional and provides evidence for two to five clusters (phenotypes) based on self-reported trait, state, and/or life-history data. Some approaches still need replication to better support whether their findings identify true phenotypes or simply different patterns of symptomatology. Regardless, these phenotyping efforts aim at improving insomnia nosology both as a classification system and as a mechanism to guide treatment.

Daytime autonomic nervous system functions differ among adults with and without insomnia symptoms

STUDY OBJECTIVES

We gathered data to determine whether daytime assays of the autonomic nervous system would differ between persons with no vs modest insomnia symptoms and would correlate with the severity of insomnia symptoms in patients.

METHODS

This report is composed of 2 studies. Study 1 conducted pupillary light reflex (PLR) measurements in community volunteers who were not seeking medical care. Study 2 contrasted PLR and heart rate variability in a different sample of community volunteers and a comparison sample of adults seeking outpatient care for insomnia and psychiatric problems. All measurements were taken between 3 and 5 pm.

RESULTS

In Study 1, volunteers with modest insomnia symptom severity had a more rapid PLR average constriction velocity compared with those with no symptoms. In Study 2, lower heart rate variability, indicating higher levels of physiologic arousal, generally were in agreement with faster PLR average constriction velocity, both of which indicate higher levels of arousal. Insomnia symptom severity was highly correlated with faster average constriction velocity in the patient sample.

CONCLUSIONS

These studies suggest that (1) daytime measurements of the autonomic nervous system differ between persons with modest vs no insomnia symptoms and (2) insomnia symptom severity is highly correlated with PLR. Daytime measurement of autonomic nervous system activity might allow for daytime point-of-care measurement to characterize the level of physiologic arousal to define a hyperarousal subtype of insomnia disorder.

CITATION

McCall WV, Looney SW, Zulfiqar M, et al. Daytime autonomic nervous system functions differ among adults with and without insomnia symptoms. J Clin Sleep Med. 2023;19(11):1885-1893.

Risk factors of suicidal behaviors in a high-risk longitudinal veteran sample: A network analysis

INTRODUCTION

Suicide is a substantial public health burden, particularly among veterans. Risk factors have been delineated for suicide; however, the dynamic interrelations between risk factors have not been fully examined. Such research has the potential to elucidate processes that contribute to suicide risk between individuals with a past suicide attempt (attempters) and those without a past suicide attempt (nonattempters).

METHODS

In the current study, network analysis was used to compare networks between attempters and nonattempters in a high-risk veteran sample (N = 770; M_age  = 32.3 years, SD = 6.8; 326 with a past suicide attempt) who were followed over 1 year. Networks were estimated to examine (1) concurrent relations of suicide risk factors at baseline and (2) predictability of prospective suicidal behavior (SB).

RESULTS

There were no differences in the overall connectivity of attempter and nonattempter networks. Perceived burdensomeness and posttraumatic stress disorder (PTSD) symptoms were most central in the attempters' network, whereas PTSD symptoms and insomnia were most central in the nonattempters' network. The risk factors prospective SB in either network. However, attempters were more likely to engage in SB over the course of the study.

CONCLUSION

These findings highlight the difficulty in predicting who will attempt suicide.

Sleep Continuity, Stability and Cyclic Organization Are Impaired in Insomniacs: A Case-Control Study

The possibility of distinguishing insomniacs from good sleepers based on polysomnography (PSG) remains an open question. While these groups show modest differences in traditional PSG parameters, some studies suggest that finer measures may be more useful. Here we assess differences between good sleepers (GS), poor sleepers (PS) and insomniacs (IN) in classical PSG measures as well as in sleep continuity, stability and cyclic organization. PSG-monitored sleep (two nights) of 17 IN (diagnosed through a standard clinical interview; Pittsburgh Sleep Quality Index (PSQI) ≥ 5, Insomnia Severity Index (ISI) > 14) was compared to that of 33 GS (PSQI < 5) and 20 PS (PSQI ≥ 5, ISI ≤ 14). Compared to GS, IN were impaired in sleep macrostructure (sleep latency, sleep efficiency, WASO%) and in continuity, stability and organization, whereas PS only showed disrupted continuity and stability. Spindle parameters were comparable between IN and GS, but the former displayed enhanced power in fast frequency bands. Our findings support the hypothesis of a continuum between individuals with self-reported poor sleep and insomniacs. Further, they add to extant data on impaired sleep continuity, stability and organization in poor sleepers and elderly individuals, underlining the utility of including these measures in standard sleep assessments.

Association between Sleep and Suicidal Ideation in Chinese Undergraduate Students

Suicide is an important global public health issue, which deserves more attention. This study aims to examine the relative independent relationship between suicide ideation and subjective sleep quality, sleep hygiene, and insomnia symptoms in undergraduate students in China. This population-based study included 2379 undergraduate students aged 18-26, randomly recruited from three public universities in Shanghai. The participants completed four questionnaires: the Pittsburgh Sleep Quality Index; Sleep Hygiene Practice Scale; Insomnia Severity Index; and the Symptom Checklist 90 (specifically the depression and anxiety dimensions and Q15-suicide ideation). The results of Spearman's correlation analysis indicate that poor sleep quality, short sleep duration, poor sleep hygiene, and insomnia symptoms were all associated with suicidal ideation in undergraduate students. However, according to the results of the hierarchical linear regression, no experience of sharing a bedroom at home, poor relationship with roommates, short sleep duration, sleep medicine use, and good daytime function were related to suicidal ideation, after controlling for the symptoms of depression and anxiety, which may be important in the identification of suicidal ideation. Sleep problems are highly discoverable and modifiable, and have a low sense of shame, therefore, sleep interventions for individuals with suicidal ideation and poor sleep quality may be an efficient and effective approach to suicide prevention.