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Journal: Sleep medicine reviews


Water-based passive body heating (PBHWB) as a warm shower or bath before bedtime is often recommended as a simple means of improving sleep. We searched PubMed, CINAHL, Cochran, Medline, PsycInfo, and Web of Science databases and extracted pertinent information from publications meeting predefined inclusion and exclusion criteria to explore the effects of PBHWB on sleep onset latency (SOL), wake after sleep onset, total sleep time, sleep efficiency (SE), slow wave sleep, and subjective sleep quality. The search yielded 5322 candidate articles of which 17 satisfied inclusion criteria after removing duplicates, with 13 providing comparable quantitative data for meta-analyses. PBHWB of 40-42.5 °C was associated with both improved self-rated sleep quality and SE, and when scheduled 1-2 h before bedtime for little as 10 min significant shortening of SOL. These findings are consistent with the mechanism of PBHWB effects being the extent of core body temperature decline achieved by increased blood perfusion to the palms and soles that augments the distal-to-proximal skin temperature gradient to enhance body heat dissipation. Nonetheless, additional investigation is required because the findings regarding PBHWB are limited by the relative scarcity of reported research, especially its optimal timing and duration plus exact mechanisms of effects.


Features of an individual’s sleep/wake patterns across multiple days are governed by two dimensions, the mean and the intraindividual variability (IIV). The existing literature focuses on the means, while the nature and correlates of sleep/wake IIV are not well understood. A systematic search of records in five major databases from inception to November 2014 identified 53 peer-reviewed empirical publications that examined correlates of sleep/wake IIV in adults. Overall, this literature appeared unsystematic and post hoc, with under-developed theoretical frameworks and inconsistent methodologies. Correlates most consistently associated with greater IIV in one or more aspects of sleep/wake patterns were: younger age, non-White race/ethnicity, living alone, physical health conditions, higher body mass index, weight gain, bipolar and unipolar depression symptomatology, stress, and evening chronotype; symptoms of insomnia and poor sleep were associated with higher sleep/wake IIV, which was reduced following sleep interventions. The effects of experimentally reduced sleep/wake IIV on daytime functioning were inconclusive. In extending current understanding of sleep/wake patterns beyond the mean values, IIV should be incorporated as an additional dimension when sleep is examined across multiple days. Theoretical and methodological shortcomings in the existing literature, and opportunities for future research are discussed.

Concepts: Science, Arithmetic mean, Mean, Body weight, Body mass index, Bipolar disorder, Dimension, Scientific method


Occidental medicine has a given definition for restless legs syndrome (RLS) and knowledge of RLS pathophysiology has led to the development of its therapeutic management. RLS has no cure. Many methods have been used for its treatment, among which traditional Chinese medicine (TCM) has been considered as a new approach. However, description and management of the disease symptoms can be found in Chinese ancient medical systems. The first mention of RLS may have been as early as the third century BC described as “leg uncomfortable”. Nonetheless, the lack of a complete description encompassing all four modern cardinal features of RLS makes this uncertain. On the other hand, the first description of RLS encompassing three of the four major modern criteria occurs in the ancient book of Neike Zhaiyao (Internal summary), 1529 AD just about a century and a half prior to the description of RLS by Sir Thomas Willis in England. Here, we introduce the philosophical concepts of traditional Chinese medicine and the description, classification and understanding of RLS symptoms in traditional Chinese medicine. We have conducted an in-depth review of the literature reporting one part of TCM, Chinese herbal treatment efficacy for RLS, through both English and Chinese search engines. Eighty-five studies were included in the review and more than 40 formulas (including 176 different ingredients) were found in the literature. According to the literature, Chinese herbs have been demonstrated to be safe and hold great potential to be an effective treatment modality for RLS, but the evidence is limited by the quality of these studies. Of the eighty-five studies, only nine were clinical trials with a control group and only three of them were randomized. In cases where herbal preparations were compared to Western medications for RLS, the herbal preparations appear to be superior. However, uncertainty as to whether the diagnosis of RLS was made in accord with Western norms and the use of homemade non-validated rating scales create uncertainty as to the meaning of these results. High-quality randomized and double blinded clinical trials of Chinese herbs in treating RLS will be required in the future. This review highlights aspects of Chinese herbal treatment important to guide future research and clinical practice. To our knowledge, this is the first systematic English review of the role of Chinese herbs in the treatment of RLS.

Concepts: Chinese classic herbal formula, Clinical trial, Li Shizhen, Alternative medicine, Herbalism, Traditional Chinese medicine, Restless legs syndrome, Chinese herbology


OBJECTIVE: To investigate diagnostic test accuracy (DTA) of different tests for obstructive sleep apnea (OSA) compared to polysomnography (PSG) in children. METHODS: We performed a systematic review according to DTA criteria published by the Cochrane Collaboration. Studies that compared any possible diagnostic test with PSG for diagnosing OSA were considered. Study quality assessment was conducted in each selected study and DTA measures recalculated by hand whenever possible. Excellent DTA was defined as positive likelihood ratio (PLR) > 10 and negative likelihood ratio (NLR) < 0.1. RESULTS: We identified 1064 potentially relevant studies, of which 33 met inclusion criteria. Study quality was generally low; 5 studies fulfilled all quality criteria and 11 studies included >100 subjects. Included studies compared 40 different tests to PSG. Only 13 studies used the currently accepted definition for OSA (i.e., apnea hypopnea index ≥1). In these studies, PLR ranged from 1.017 to ∞, NLR from 0 to 1.089. Sleep lab-based polygraphy, urinary biomarkers, and rhinomanometry (one study each) showed excellent DTA. CONCLUSION: There is limited evidence concerning diagnostic alternatives to PSG for identifying OSA in children. However, polygraphy, urinary biomarkers, and rhinomanometry may be valid tests if their apparently high DTA is confirmed by subsequent studies.

Concepts: Systematic review, Diagnosis, Likelihood-ratio test, Sleep disorder, Evidence-based medicine, Hypopnea, Obstructive sleep apnea, Sleep apnea


From disaster related stress causing insomnia, to poor air quality causing sleep related breathing problems, climate change poses a potentially serious threat to human sleep. We conducted a systematic review evaluating the relationship between climate change and human sleep in the PubMed, Scopus, and Cochrane databases from 1980 through 2017 following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Inclusion criteria included epidemiologic studies published in English that reported observational population data on human sleep and its relationship to climate change, temperature, extreme weather events and climate related disasters (e.g. hurricanes, floods, and wildfires). We excluded non-human studies, laboratory or experimental physiology studies, commentaries or letters, review articles, and articles on wind turbines. Using a systematic search strategy, 16 studies met the inclusion criteria. Six studies related to the effects of rising temperature, seven studies related to extreme weather events, and three studies related to floods or wildfires. Diminished total sleep times and sleep disruption were most commonly reported, especially among the most vulnerable populations including the elderly and low-income; however, the body of evidence was limited and further well-designed human studies are clearly needed. We present a conceptual framework for identifying the emerging threats of climate change and understanding their respective effects on human sleep.


We systematically examined and updated the scientific literature on the association between screen time (e.g., television, computers, video games, and mobile devices) and sleep outcomes among school-aged children and adolescents. We reviewed 67 studies published from 1999 to early 2014. We found that screen time is adversely associated with sleep outcomes (primarily shortened duration and delayed timing) in 90% of studies. Some of the results varied by type of screen exposure, age of participant, gender, and day of the week. While the evidence regarding the association between screen time and sleep is consistent, we discuss limitations of the current studies: 1) causal association not confirmed; 2) measurement error (of both screen time exposure and sleep measures); 3) limited data on simultaneous use of multiple screens, characteristics and content of screens used. Youth should be advised to limit or reduce screen time exposure, especially before or during bedtime hours to minimize any harmful effects of screen time on sleep and well-being. Future research should better account for the methodological limitations of the extant studies, and seek to better understand the magnitude and mechanisms of the association. These steps will help the development and implementation of policies or interventions related to screen time among youth.

Concepts: GNU Screen, Error, The Association, Systematic review, Measurement, Shutter speed


OBJECTIVES: Sleep problems are a potential risk factor for work injuries but the extent of the risk is unclear. We conducted a systematic review and meta-analysis to quantify the effect of sleep problems on work injuries. METHODS: A systematic literature search using several databases was performed. Sleep problems of any duration or frequency as well as work injuries of any severity were of interest. The effect estimates of the individual studies were pooled and relative risks (RR) and 95% confidence intervals (CI) were calculated through random effects models. Additionally, the population attributable risk was estimated. RESULTS: In total, 27 observational studies (n = 268,332 participants) that provided 54 relative risk estimates were included. The findings of the meta-analysis suggested that workers with sleep problems had a 1.62 times higher risk of being injured than workers without sleep problems (RR: 1.62, 95% CI: 1.43-1.84). Approximately 13% of work injuries could be attributed to sleep problems. CONCLUSION: This systematic review confirmed the association between sleep problems and work injuries and, for the first time, quantified its magnitude. As sleep problems are of growing concern in the population, these findings are of interest for both sleep researchers and occupational physicians.

Concepts: Risk management, Statistics, Risk, Meta-analysis, Systematic review, Relative risk, Medical statistics, Epidemiology


Emerging longitudinal research has highlighted poor sleep as a risk factor of a range of adverse health outcomes, including disabling pain conditions. In establishing the causal role of sleep in pain, it remains to be clarified whether sleep deterioration over time is a driver of pain and whether sleep improvement can mitigate pain-related outcomes. A systematic literature search was performed using PubMed MEDLINE, Ovid EMBASE, and Proquest PsycINFO, to identify 16 longitudinal studies involving 61,000 participants. The studies evaluated the effect of sleep changes (simulating sleep deterioration, sleep stability, and sleep improvement) on subsequent pain-related outcomes in the general population. A decline in sleep quality and sleep quantity was associated with a two- to three-fold increase in risk of developing a pain condition, small elevations in levels of inflammatory markers, and a decline in self-reported physical health status. An exploratory meta-analysis further revealed that deterioration in sleep was associated with worse self-reported physical functioning (medium effect size), whilst improvement in sleep was associated with better physical functioning (small effect size). The review consolidates evidence that changes in sleep are prospectively associated with pain-related outcomes and highlights the need for further longitudinal investigations on the long-term impact of sleep improvements.


During the last decade, many clinical and pathophysiological aspects of sleep-related epileptic and non-epileptic paroxysmal behaviors have been clarified. Advances have been achieved in part through the use of intracerebral recording methods such as stereo-electroencephalography (S-EEG), which has allowed a unique “in vivo” neurophysiological insight into focal epilepsy. Using S-EEG, the local features of physiological and pathological EEG activity in different cortical and subcortical structures have been better defined during the entire sleep-wake spectrum. For example, S-EEG has contributed to clarify the semiology of sleep-related seizures as well as highlight the specific epileptogenic networks involved during ictal activity. Moreover, intracerebral EEG recordings derived from patients with epilepsy have been valuable to study sleep physiology and specific sleep disorders. The occasional co-occurrence of NREM-related parasomnias in epileptic patients undergoing S-EEG investigation has permitted the recordings of such events, highlighting the presence of local electrophysiological dissociated states and clarifying the underlying pathophysiological substrate of such NREM sleep disorders. Based on these recent advances, the authors review and summarize the current and relevant S-EEG literature on sleep-related hypermotor epilepsies and NREM-related parasomnias. Finally, novel data and future research hypothesis will be discussed.

Concepts: Neurology, Non-rapid eye movement sleep, Sleep, Myoclonus, Seizure, Epilepsy, Electroencephalography


We examined the dose-response relationship between long sleep duration and health outcomes including mortality and the incidence of diabetes mellitus, hypertension, cardiovascular diseases, stroke, coronary heart diseases, obesity, depression and dyslipidemia. We collected data from 5,134,036 participants from 137 prospective cohort studies. For the independent variable, we categorized participants at baseline as having long sleep duration or normal sleep duration. Risk ratios (RRs) for mortality and incident health conditions during follow-up were calculated through meta-analyses of adjusted data from individual studies. Meta-regression analyses were performed to investigate the association between each outcome and specific thresholds of long sleep. Long sleep was significantly associated with mortality (RR, 1.39; 95% CI, 1.31-1.47), incident diabetes mellitus (1.26, 1.11-1.43), cardiovascular disease (1.25, 1.14-1.37), stroke (1.46, 1.26-1.69), coronary heart disease (1.24, 1.13-1.37), and obesity (1.08, 1.02-1.15). Long sleep was not significantly related to incident hypertension (1.01, 0.95-1.07). Insufficient data were available for depression and dyslipidemia. Meta-regression analyses found statistically significant linear associations between longer sleep duration and increased mortality and incident cardiovascular disease. Future studies should address whether the relationship between long sleep and health outcomes is causal and modifiable.