Obstructive sleep apnea and risk of Parkinson's disease: a population‐based cohort study

Sleep disorders could be associated with neurodegenerative diseases. This study aimed to determine the risk of Parkinson's disease in patients with obstructive sleep apnea. The incident cases of newly diagnosed obstructive sleep apnea were identified between 2000 and 2009 from the medical claims database of National Health Institute of Taiwan. The risk of Parkinson's disease onset at least 1 year after the diagnosis of obstructive sleep apnea was measured during and up to 11 years of period, compared to that of age‐ and gender‐matched controls estimated in the same period. A total of 5864 patients with newly diagnosed obstructive sleep apnea and 23 269 subjects without obstructive sleep apnea were identified for data analysis. The study reported that the incidence of Parkinson's disease in the obstructive sleep apnea cohort was approximately two times higher than that in the control cohort (2.57 versus 1.32 per 1000 person‐years), with an adjusted hazard ratio of 1.84. Furthermore, the risk of Parkinson's disease was particularly greater for the obstructive sleep apnea with insomnia subgroup (adjusted hazard ratio = 1.97, 95% confidence interval = 1.44–2.69) than for the control cohort. The sex–age‐specific analysis further discovered that the most elevated risk of Parkinson's disease onset was noted in female obstructive sleep apnea patients aged 50–69 years (adjusted hazard ratio = 2.82). This population‐based study indicated that patients with obstructive sleep apnea, especially those who suffered from insomnia, are at an increased risk of Parkinson's disease onset.     

Relationships of sleep duration with sociodemographic and health‐related factors,psychiatric disorders and sleep disturbances in a community sample of Korean adults

The aim of this study is to examine relationships of sleep duration with sociodemographic and health‐related factors, psychiatric disorders and sleep disturbances in a nationwide sample in Korea. A total of 6510 subjects aged 18–64 years participated in this study. Logistic regression was used to calculate the odd ratios and 95% confidence intervals of the covariates, psychiatric disorders and sleep disturbances across the following sleep duration categories: 5 h or less, 6, 7, 8 and 9 h or more per day. Low levels of education, unemployment and physical illness were associated with sleeping for 5 h or less and 9 h or more. Being older and widowed/divorced/separated, high levels of physical activity, pain/discomfort, obesity and high scores on the General Health Questionnaires were associated with sleeping for 5 h or less. Female, being younger and underweight were associated with sleeping for 9 h or more. Alcohol dependence, anxiety disorder and social phobia were associated significantly with sleeping for 5 h or less and 9 h or more. Other psychiatric disorders were more common in subjects who slept for 5 h or less (e.g. alcohol use disorder, mood disorder, major depressive disorder, dysthymic disorder, obsessive‐compulsive disorder and specific phobia) or 9 h or more (e.g. post‐traumatic stress disorder). In addition, subjects who slept for 5 h or less reported more sleep disturbances than did subjects who slept for 7 h. Short or long sleep is associated with psychiatric disorders and/or sleep disturbance, therefore attention to the mental health of short or long sleepers is needed.     

Association between symptoms and subtypes of attention‐deficit hyperactivity disorder and sleep problems/disorders

This study aimed to investigate the association between attention‐deficit hyperactivity disorder (ADHD) symptoms and subtypes, and sleep schedules, daytime inadvertent napping, and sleep problems/disorders in children and adolescents with and without ADHD. The sample included 325 patients with ADHD, aged 10–17 years [male: 81.5%; combined type (ADHD‐C): 174; predominantly inattentive type (ADHD‐I): 130; predominantly hyperactive‐impulsive type (ADHD‐HI): 21], and 257 children and adolescents without lifetime ADHD (non‐ADHD). We conducted psychiatric interviews with the participants and their mothers before making the diagnoses of ADHD, other psychiatric disorders, and sleep problems or disorders. We also collected the medication treatment data and parent and teacher reports of ADHD symptoms. Multi‐level models were used for data analyses controlling for sex, age, psychiatric comorbidities, and treatment with methylphenidate. The ADHD‐C and ADHD‐I groups had more daytime inadvertent napping. In general, the three subtypes were associated with increased rates of sleep problems/disorders. Specifically, ADHD‐C rather than ADHD‐I was associated with circadian rhythm problems, sleep‐talking, nightmares (also ADHD‐HI), and ADHD‐I was associated with hypersomnia. The most‐related sleep schedules and problems for inattention and hyperactivity‐impulsivity were earlier bedtime, later rise time, longer nocturnal sleep, more frequent daytime napping, insomnia, sleep terrors, sleep‐talking, snoring, and bruxism across informants. The findings imply that in addition to the dichotomous approach of ADHD and considering the psychiatric comorbid conditions, ADHD subtypes and symptom dimensions need to be considered in clinical practice and in the research regarding the association between ADHD and sleep problems/disorders.     

Sleep duration and sleep disturbances partly explain the association between depressive symptoms and cardiovascular mortality: the Whitehall II cohort study

Depressive symptoms are associated with an increased risk of death, but most of this association remains unexplained. Our aim was to explore the contribution of sleep duration and disturbances to the association between depressive symptoms, all‐cause and cardiovascular disease mortality. A total of 5813 (4220 men and 1593 women) aged 50–74 years at baseline, participants of the British Whitehall II prospective cohort study, were included. Depressive symptoms, sleep duration and disturbances were assessed in 2003–04. Mortality was ascertained through linkage to the national mortality register until August 2012, with a mean follow‐up of 8.8 years. Depressive symptoms were associated with an increased risk of mortality from all causes [hazard ratio (HR) = 1.51; 95% confidence interval (CI): 1.16–1.97)] and cardiovascular diseases (HR = 1.63; 95% CI: 1.01–2.64) after adjustment for sociodemographic characteristics. Further adjustment for sleep duration and disturbances reduced the association between depressive symptoms and cardiovascular mortality by 21% (HR = 1.53; 95% CI: 0.91–2.57). Sleep seems to have a role, as a mediator or confounder, in explaining the association between depressive symptoms and cardiovascular mortality. These findings need replication in larger studies with longer follow‐up.     

Link between insomnia and perinatal depressive symptoms: A meta‐analysis

Evidence shows the possible link between insomnia and perinatal depressive symptoms. In order to find a convergent quantitative answer, we collected data via the search of Medline, EMBASE and reference tracking, which included nine studies (a total sample of 1,922 women). An aggregate effect size estimate (correlation coefficient) was generated using the comprehensive meta‐analysis software. For the meta‐analytic procedure, a random effects model was set a priori. Moderating factors, including study design, method of assessment of depression, geographical origin of data, publication year, mean age, % married, breastfeeding rate, quality and type of data, % primiparous and history of depression, were examined via categorical or univariate mixed‐effects (method of moments) meta‐regression methods. Heterogeneity and publication bias were examined using standard meta‐analytic approaches. We found a significant, medium‐size relationship between insomnia and perinatal depressive symptoms (point estimate, 0.366; 95% confidence interval [CI], 0.205–0.508; p < 0.001; n = 9) and this was significantly heterogeneous (Q, 118.77; df, 8; p < 0.001; I², 93.26%). The effect size estimate was significant for studies reporting no history of depression (point estimate, 0.364; 95% CI, 0.035–0.622; p < 0.05; n = 5) and for study design. With meta‐regression, no moderating factor (age, marriage rate, breastfeeding rate, pregnancy history or publication year) significantly mediated the effect size estimate. The depression assessment scale used, but not other categorical variables, explained the magnitude of heterogeneity. We found that insomnia during the perinatal period is associated with depressive symptoms, which warrants screening pregnant mothers for insomnia and depression.     

Prevalence of sleep disturbances in Chinese university students: a comprehensive meta‐analysis

This is a meta‐analysis of the pooled prevalence of sleep disturbances and its associated factors in Chinese university students. English (PubMed, PsycINFO, Embase) and Chinese (SinoMed, Wan Fang Database and Chinese National Knowledge Infrastructure) databases were systematically and independently searched from inception until 16 August 2016. The prevalence of sleep disturbances was pooled using random‐effects model. Altogether 76 studies involving 112 939 university students were included. The overall pooled prevalence of sleep disturbances was 25.7% (95% CI: 22.5–28.9%). When using the screening scales Pittsburgh Sleep Quality Index, Athens Insomnia Scale and Self‐Rating Sleeping State Scale, and the diagnostic criteria of the Chinese Classification of Mental Disorders (Second Edition), the pooled prevalence of sleep disturbances was 24.1% (95% CI: 21.0–27.5%) and 18.1% (95% CI: 16.4–20.0%), respectively. The percentages of students dissatisfied with sleep quality and those suffering from insomnia symptoms were 20.3% (95% CI: 13.0–30.3%) and 23.6% (95% CI: 18.9–29.0%), respectively. Subgroup analyses revealed that medical students were more vulnerable to sleep disturbances than other student groups. There was no significant difference between males and females, and across geographic locations. Sleep disturbances are common in Chinese university students. Appropriate strategies for prevention and treatment of sleep disturbances in this population need greater attention.     

Work stressors,depressive symptoms and sleep quality among US Navy members: a parallel process latent growth modelling approach across deployment

The present study examined whether work stressors contribute to sleep problems and depressive symptoms over the course of deployment (i.e. pre‐deployment, post‐deployment and 6‐month reintegration) among US Navy members. Specifically, we examined whether depressive symptoms or sleep quality mediate the relationships between work stressors and these outcomes. Participants were 101 US Navy members who experienced an 8‐month deployment after Operational Enduring Freedom/Operation Iraqi Freedom. Using piecewise latent growth models, we found that increased work stressors were linked to increased depressive symptoms and decreased sleep quality across all three deployment stages. Further, increases in work stressors from pre‐ to post‐deployment contributed to poorer sleep quality post‐deployment via increasing depressive symptoms. Moreover, sleep quality mediated the association between increases in work stressors and increases in depressive symptoms from pre‐ to post‐deployment. These effects were maintained from post‐deployment through the 6‐month reintegration. Although preliminary, our results suggest that changes in work stressors may have small, but significant implications for both depressive symptoms and quality of sleep over time, and a bi‐directional relationship persists between sleep quality and depression across deployment. Strategies that target both stress and sleep could address both precipitating and perpetuating factors that affect sleep and depressive symptoms.     

Modafinil in the treatment of idiopathic hypersomnia without long sleep time—a randomized,double‐blind,placebo‐controlled study

In 2010 the European Medicines Agency withdrew the indication of modafinil for the treatment of obstructive sleep apnea, shift work sleep disorder and for idiopathic hypersomnia (IH). In uncontrolled studies, modafinil has been reported to be efficacious in the treatment of sleep disorders. We therefore performed a randomized, placebo‐controlled study with the aim of proving the efficacy of modafinil treatment in these patients. Drug‐free IH patients without long sleep according to ICSD2 criteria, age >18 years and disease duration >2 years were included. After a washout phase, patients at baseline received placebo or 100 mg modafinil in the morning and at noon over 3 weeks, followed by 1 week without medication. At each visit the Epworth Sleepiness Scale (ESS) and Clinical Global Impression (CGI) rating scale were performed. At baseline and on days 8 and 21 four Maintenance of Wakefulness Tests (MWTs)/day or per day were performed. Patients kept a sleep–wake diary throughout the study. Between 2009 and 2011 three sleep centres recruited 33 participants. Compared to placebo, modafinil decreased sleepiness significantly and improved mean sleep latency in the MWT non‐significantly. The CGI improved significantly from baseline to the last visit on treatment. The most frequent adverse events were headaches and gastrointestinal disorders; skin and psychiatric reactions were not reported. The number of reported naps and duration of daytime sleepiness decreased significantly. Total sleep time of nocturnal sleep was slightly reduced. The sleep diaries showed increases in feeling refreshed in the morning; the diurnal diaries showed significant improvement of performance and of exhaustion. Modafinil is an effective and safe medication in the treatment of IH. Adverse events are mild to moderate.     

Patterns of performance degradation and restoration during sleep restriction and subsequent recovery: a sleep dose-response study

Daytime performance changes were examined during chronic sleep restriction or augmentation and following subsequent recovery sleep. Sixty-six normal volunteers spent either 3 (n = 18), 5 (n= 16), 7 (n = 16), or 9 h (n = 16) daily time in bed (TIB) for 7 days (restriction/augmentation) followed by 3 days with 8 h daily TIB (recovery). In the 3-h group, speed (mean and fastest 10% of responses) on the psychomotor vigilance task (PVT) declined, and PVT lapses (reaction times greater than 500 ms) increased steadily across the 7 days of sleep restriction. In the 7- and 5-h groups speed initially declined, then appeared to stabilize at a reduced level; lapses were increased only in the 5-h group. In the 9-h group, speed and lapses remained at baseline levels. During recovery, PVT speed in the 7- and 5-h groups (and lapses in the 5-h group) remained at the stable, but reduced levels seen during the last days of the experimental phase, with no evidence of recovery. Speed and lapses in the 3-h group recovered rapidly following the first night of recovery sleep; however, recovery was incomplete with speed and lapses stabilizing at a level comparable with the 7- and 5-h groups. Performance in the 9-h group remained at baseline levels during the recovery phase. These results suggest that the brain adapts to chronic sleep restriction. In mild to moderate sleep restriction this adaptation is sufficient to stabilize performance, although at a reduced level. These adaptive changes are hypothesized to restrict brain operational capacity and to persist for several days after normal sleep duration is restored, delaying recovery.     

Maternal depressive symptoms,sleep, and odds of spontaneous early birth: implications for racial inequities in birth outcomes

Study ObjectivesDelivery prior to full term affects 37% of US births, including ~400,000 preterm births (<37 weeks) and >1,000,000 early term births (37–38 weeks). Approximately 70% of cases of shortened gestation are spontaneous—without medically-indicated cause. Elucidation of modifiable behavioral factors would have considerable clinical impact.MethodsThis study examined the role of depressive symptoms and sleep quality in predicting the odds of spontaneous shortened gestation among 317 women (135 black, 182 white) who completed psychosocial assessment in mid-pregnancy.ResultsAdjusting for key covariates, black women had 1.89 times higher odds of spontaneous shortened gestation compared to White women (OR [95% CI] = 1.89 [1.01, 3.53], p = 0.046). Women who reported only poor subjective sleep quality (PSQI > 6) or only elevated depressive symptoms (CES-D ≥ 16) exhibited no statistically significant differences in odds of spontaneous shortened gestation compared to those with neither risk factor. However, women with comorbid poor sleep and depressive symptoms exhibited markedly higher odds of spontaneous shortened gestation than those with neither risk factor (39.2% versus 15.7% [OR (95% CI) = 2.69 (1.27, 5.70)], p = 0.01). A higher proportion of black women met criteria for both risk factors (23% of black women versus 11% of white women; p = 0.004), with a lower proportion experiencing neither risk factor (40.7% of black versus 64.3% of white women; p < 0.001).ConclusionsAdditive effects of poor subjective sleep quality and depressive symptoms were observed with markedly higher odds of spontaneous shortened gestation among women with both risk factors. Racial inequities in rates of comorbid exposure corresponded with inequities in shortened gestation. Future empirical studies and intervention efforts should consider the interactive effects of these commonly co-morbid exposures.     

Slow oscillating transcranial direct current stimulation during sleep has a sleep‐stabilizing effect in chronic insomnia: a pilot study

Recent evidence suggests that lack of slow‐wave activity may play a fundamental role in the pathogenesis of insomnia. Pharmacological approaches and brain stimulation techniques have recently offered solutions for increasing slow‐wave activity during sleep. We used slow (0.75 Hz) oscillatory transcranial direct current stimulation during stage 2 of non‐rapid eye movement sleeping insomnia patients for resonating their brain waves to the frequency of sleep slow‐wave. Six patients diagnosed with either sleep maintenance or non‐restorative sleep insomnia entered the study. After 1 night of adaptation and 1 night of baseline polysomnography, patients randomly received sham or real stimulation on the third and fourth night of the experiment. Our preliminary results show that after termination of stimulations (sham or real), slow oscillatory transcranial direct current stimulation increased the duration of stage 3 of non‐rapid eye movement sleep by 33 ± 26 min (P = 0.026), and decreased stage 1 of non‐rapid eye movement sleep duration by 22 ± 17.7 min (P = 0.028), compared with sham. Slow oscillatory transcranial direct current stimulation decreased stage 1 of non‐rapid eye movement sleep and wake time after sleep‐onset durations, together, by 55.4 ± 51 min (P = 0.045). Slow oscillatory transcranial direct current stimulation also increased sleep efficiency by 9 ± 7% (P = 0.026), and probability of transition from stage 2 to stage 3 of non‐rapid eye movement sleep by 20 ± 17.8% (P = 0.04). Meanwhile, slow oscillatory transcranial direct current stimulation decreased transitions from stage 2 of non‐rapid eye movement sleep to wake by 12 ± 6.7% (P = 0.007). Our preliminary results suggest a sleep‐stabilizing role for the intervention, which may mimic the effect of sleep slow‐wave‐enhancing drugs.     

The interplay between daily affect and sleep: a 2‐week study of young women

Little attention has been paid to the relation between daily affect and sleep, as most prior studies have focused instead on the role of pathological mood in the context of sleep disturbance. However, understanding the transaction between normal variations in emotional experiences and sleep can shed light on the premorbid vulnerabilities that trigger the evolution of affect and sleep into more problematic states. The present study used a 2‐week daily sampling approach to examine the impact of day‐to‐day variations in positive and negative affect on nightly self‐reported sleep‐onset latency, sleep duration and sleep quality in a sample of young women. Hierarchical linear modelling revealed temporal relations between positive and negative affect states and sleep parameters. Specifically, different aspects of both positive and negative affect were uniquely predictive of sleep indices, with sadness and serenity acting as the most consistent predictors. Additionally, better sleep quality was predictive of greater happiness the following day. These results highlight the importance of how our daily emotional experiences influence our nightly sleep and, in turn, how our sleep has an impact on our daily affect. Moreover, our findings may offer insight into the progression of normative levels of affect and sleep as they develop into comorbid depression, anxiety and insomnia.     

Association of sleep duration with weight and weight gain: a prospective follow-up study

The objective of this study was to examine the associations of sleep duration with subsequent weight and major weight gain in women and men during a follow-up period of 5-7years. The data were derived from the Helsinki Health Study cohort mail questionnaire surveys among 40-60-year-old employees of the City of Helsinki, Finland. At baseline in 2000-2002, 8960 people responded to the survey (80% women, response rate 67%). The follow-up survey was conducted in 2007 among all respondents to the baseline survey (n=7332, response rate 83%). Sleep duration (5h or less up to 10h or more) and weight and weight gain of at least 5kg were based on self-reports. Analyses of variance and logistic regression analyses were used to examine the associations between sleep duration and weight, as well as major weight gain. Short sleep duration was associated with major weight gain [odds ratio (OR) 1.52; 95% confidence interval (CI) 1.08, 2.14] during the follow-up. Adjusting for several covariates had only minor effects on that association. Long sleep duration was associated with major weight gain after adjusting for age (OR 1.35; 95% CI 1.00-1.81). No associations were found among men. Sleep duration was associated with major weight gain among middle-aged employed women. Short sleep may be a risk factor for subsequent weight gain.     

Sleep quality and the risk of work injury: a Swiss case–control study

Sleep problems are a well‐known risk factor for work injuries, but less is known about which vulnerable populations are most at risk. The aims of this study were to investigate the association between sleep quality and the risk of work injury and to identify factors that may modify the association. A case–control study including 180 cases and 551 controls was conducted at the University Hospital in Basel, Switzerland, from 1 December 2009 to 30 June 2011. Data on work injuries and sleep quality were collected. Adjusted odds ratios and 95% confidence intervals of the association between sleep quality and work injury were estimated in multivariable logistic regression analyses and were stratified by hypothesized effect modifiers (age, gender, job risk, shift work, sleep duration and working hours). Poor sleep quality was associated significantly with work injury of any type (P < 0.05) and with being caught in particular (P < 0.05). The association between poor sleep quality and work injury was significantly higher for workers older than 30 years (odds ratio_>30 1.30 versus odds ratio_≤30 0.91, P < 0.01), sleeping 7 h or less per night (odds ratio_≤7 1.17 versus odds ratio_>7 0.79, P < 0.05) and working 50 h or more per week (odds ratio_≥50 1.79 versus odd ratio_<50 1.10, P < 0.01). Work injury risk increased with increasing severity of sleep problems (P < 0.05). Prior work injury frequency increased with decreasing sleep quality (P < 0.05). Older age, short sleep duration and long working hours may enhance the risk of work injuries associated with sleep quality.     

Enhanced brain small‐worldness after sleep deprivation: a compensatory effect

Sleep deprivation has a variable impact on extrinsic activities during multiple cognitive tasks, especially on mood and emotion processing. There is also a trait‐like individual vulnerability or compensatory effect in cognition. Previous studies have elucidated the altered functional connectivity after sleep deprivation. However, it remains unclear whether the small‐world properties of resting‐state network are sensitive to sleep deprivation. A small‐world network is a type of graph that combines a high local connectivity as well as a few long‐range connections, which ensures a higher information‐processing efficiency at a low cost. The complex network of the brain can be described as a small‐world network, in which a node is a brain region and an edge is present when there is a functional correlation between two nodes. Here, we investigated the topological properties of the human brain networks of 22 healthy subjects under sufficient sleep and sleep‐deprived conditions. Specifically, small‐worldness is utilized to quantify the small‐world property, by comparing the clustering coefficient and path length of a given network to an equivalent random network with same degree distribution. After sufficient sleep, the brain networks showed the property of small‐worldness. Compared with the resting state under sufficient sleep, the small‐world property was significantly enhanced in the sleep deprivation condition, suggesting a possible compensatory adaptation of the human brain. Specifically, the altered measurements were correlated with the neuroticism of subjects, indicating that individuals with low‐levels of neuroticism are more resilient to sleep deprivation.     

Comparison of a single‐channel EEG sleep study to polysomnography

An accurate home sleep study to assess electroencephalography (EEG)‐based sleep stages and EEG power would be advantageous for both clinical and research purposes, such as for longitudinal studies measuring changes in sleep stages over time. The purpose of this study was to compare sleep scoring of a single‐channel EEG recorded simultaneously on the forehead against attended polysomnography. Participants were recruited from both a clinical sleep centre and a longitudinal research study investigating cognitively normal ageing and Alzheimer's disease. Analysis for overall epoch‐by‐epoch agreement found strong and substantial agreement between the single‐channel EEG compared to polysomnography (κ = 0.67). Slow wave activity in the frontal regions was also similar when comparing the single‐channel EEG device to polysomnography. As expected, Stage N1 showed poor agreement (sensitivity 0.2) due to lack of occipital electrodes. Other sleep parameters, such as sleep latency and rapid eye movement (REM) onset latency, had decreased agreement. Participants with disrupted sleep consolidation, such as from obstructive sleep apnea, also had poor agreement. We suspect that disagreement in sleep parameters between the single‐channel EEG and polysomnography is due partially to altered waveform morphology and/or poorer signal quality in the single‐channel derivation. Our results show that single‐channel EEG provides comparable results to polysomnography in assessing REM, combined Stages N2 and N3 sleep and several other parameters, including frontal slow wave activity. The data establish that single‐channel EEG can be a useful research tool.