Does sleep deprivation increase the vulnerability to acute psychosocial stress in young and older adults?

The effect of total sleep deprivation on autonomic nervous system and cortisol responses to acute stressors in healthy individuals: A systematic review

OBJECTIVE

To synthesise the literature examining the autonomic nervous system (ANS) and cortisol responses to an acute stressor following total sleep deprivation (TSD) in healthy adult subjects.

METHODS

We conducted a systematic review (CRD42022293857) following the latest PRISMA statement. We searched Medline (via Ovid), Embase (via Ovid), PsycINFO (via Ovid), CINAHL complete and Scopus databases, without year restriction, using search terms related to "sleep deprivation", "stress", "autonomic nervous system" and "cortisol". Two independent team members used pre-defined inclusion/exclusion criteria to assess eligibility and extract data. We used RoB 2 to assess the risk of bias in randomised controlled trials, and ROBINS-I for non-randomised studies.

RESULTS

Sixteen studies, with 581 participants (mean age = 29 ± 12 years), were eligible for inclusion in the descriptive syntheses. Half of the studies (n = 8) were conducted in the United States of America. The most commonly used study designs were randomised crossover studies (n = 7) and randomised controlled trials (n = 5). Most studies used a single night of TSD (n = 13) which was followed by a psychological (n = 6), physical (n = 5) or psychological and physical (n = 5) acute stressor event. Heart rate (n = 8), cortisol (n = 7) and blood pressure (n =6) were the most reported outcomes, while only a single study used forearm vascular conductance and forearm blood flow. Ten studies found that TSD changed, at least, one marker of ANS or cortisol response. TSD compared with a sleep control condition increased cortisol level (n=1), systolic blood pressure (n=3), diastolic blood pressure (n=2), mean arterial pressure (n=1), and electrodermal activity (n=1) after acute stress. Also, compared with a sleep control, TSD blunted cortisol (n=2), heart rate (n=1) and systolic blood pressure (n=2) responses after acute stress. However, TSD did not change ANS or cortisol responses to acute stressors in 73 % of the total reported outcomes. Furthermore, 10 RCT studies (62.5 %) were assigned as "some concerns" and two RCT studies (12.5 %) were attributed "high" risk of bias. Additionally, one non-randomised trial was classified as "moderate" and three non-randomised trials as "serious" risk of bias.

CONCLUSION

The markers of ANS and cortisol responses to acute stress after TSD in healthy individuals reveal a scarcity of consistent evidence. The included studies present enough evidence that TSD induces either blunted or exaggerated ANS or cortisol responses to laboratory stresses supporting the "bidirectional multi-system reactivity hypothesis.". It appears that a comprehensive understanding of this phenomenon still lacks robust evidence, and further research is needed to clarify these relationships.

The new science of sleep: From cells to large-scale societies

In the past 20 years, more remarkable revelations about sleep and its varied functions have arguably been made than in the previous 200. Building on this swell of recent findings, this essay provides a broad sampling of selected research highlights across genetic, molecular, cellular, and physiological systems within the body, networks within the brain, and large-scale social dynamics. Based on this raft of exciting new discoveries, we have come to realize that sleep, in this moment of its evolution, is very much polyfunctional (rather than monofunctional), yet polyfunctional for reasons we had never previously considered. Moreover, these new polyfunctional insights powerfully reaffirm sleep as a critical biological, and thus health-sustaining, requisite. Indeed, perhaps the only thing more impressive than the unanticipated nature of these newly emerging sleep functions is their striking divergence, from operations of molecular mechanisms inside cells to entire group societal dynamics.

Salivary α-amylase as a marker of sleep disorders: A theoretical review

Sleep disorders are commonplace in our modern societies. Specialized hospital departments are generally overloaded, and sleep assessment is an expensive process in terms of equipment, human resources, and time. Biomarkers would usefully complement current measures in the screening and follow-up of sleep disorders and their daytime repercussions. Among salivary markers, a growing body of literature suggests that salivary α-amylase (sAA) may be a cross-species marker of sleep debt. However, there is no consensus as to the direction of variation in sAA with sleep disorders. Herein, after describing the mechanisms of sAA secretion and its relationship with stress, studies assessing the relationship between sAA and sleep parameters are reviewed. Finally, the influence of confounding factors is discussed, along with methodological considerations, to better understand the fluctuations in sAA and facilitate future studies in the field.

Understanding the combined effects of sleep deprivation and acute social stress on cognitive performance using a comprehensive approach

Background

Sleep deprivation (SD) and acute social stress are common, often unavoidable, and frequently co-occurring stressors in high-risk professions. Both stressors are known to acutely induce inflammatory responses and an increasing body of literature suggests this may lead to cognitive impairment. This study examined the combined effects of total SD and acute social stress on cognitive performance and took a comprehensive approach to explore their (shared) underlying mechanism leading to cognitive decline.

Method

We recorded cognitive performance on a response inhibition task and a multitask and monitored a range of inflammatory, psychophysiological and self-reported markers in 101 participants, both before and after one night of either sleep (control group: N = 48) or SD (N = 53), and both before and after a social stressor (Trier Social Stress Test).

Results

SD decreased cognitive performance. The social stress test also results in cognitive performance decline in the control group on the response inhibition task, but improved rather than decreased performance of sleep deprived participants on both tasks. The subjective ratings of mental effort also reflect this antagonistic interaction, indicating that the social stressor when sleep-deprived also reduced mental effort. In the inflammatory and physiological measures, this pattern was only reflected by IL-22 in blood. SD reduced blood IL-22 concentrations, and the social stress reduced IL-22 in the control group as well, but not in sleep-deprived participants. There were no interactive effects of SD and social stress on any other inflammatory or psychophysiological measures. The effects of the social stress test on autonomic measures and subjective results suggest that increased arousal may have benefited sleep-deprived participants' cognitive performance.

Discussion

SD generally decreased cognitive performance and increased required mental effort. By contrast, the isolated effects of a social stressor were not generic, showing a positive effect on cognitive performance when sleep deprived. Our study is the first that studied combined effects of sleep deprivation and acute social stress on cognitive performance and inflammatory markers. It provides a comprehensive overview of effects of these stressors on a range of variables. We did not show unequivocal evidence of an underlying physiological mechanism explaining changes in performance due to (the combination of) sleep deprivation and social stress, but consider IL-22 as a possible cytokine involved in this mechanism and certainly worth following up on in future research.

Implications of sleep disorders for periodontitis

PURPOSE

Periodontitis is a chronic inflammatory disease caused by multi-factors. Sleep is a natural physiologic process, and the sleep duration, quality, and patterns might be associated with periodontitis. Meanwhile, periodontitis might in turn induce systemic inflammation and thus impact sleep in different ways as well.

METHODS

To investigate the bidirectional relationship between sleep disorder and periodontitis, a literature search was conducted to reveal the interaction and possible mechanism between these two diseases.

RESULTS

The results show that sleep disorders can affect the progression of periodontitis via some pathomechanisms, and periodontitis also has a reverse impact on sleep.

CONCLUSION

Although the epidemiologic and clinical trials found the possible associations between sleep disorder and periodontitis, their relationship is still not that explicit. Further studies are warranted to shed light on them, to improve preventive health care.

Sleep quality and duration: A key to life satisfaction among military students

Military service is a demanding profession that requires high physical preparedness and mental endurance. At the same time, the demands of military duties often require early rising and shortened sleep duration. Such a reduction in sleep can reduce physical and mental performance, and these changes can be reflected in life satisfaction. For this reason, soldiers' life satisfaction is a crucial variable for their success and long-term service. This study examined the relationship between sleep quality, sleep duration, and life satisfaction in military medical students. The results on 35 military students showed that greater sleep quality corresponded to greater life satisfaction; this relationship was moderate and significant (r = -460, p = .005). Notably, participants (n = 17) who began to wake up without the use of an alarm clock reported an average of 11% higher life satisfaction than the participants who woke to an alarm clock; this difference between participants was statistically significant (p = .011, Cohen's d = .911). Pre- and post-intervention showed that sleep hygiene education could be a suitable solution to prevent sleep deprivation and positively impact life satisfaction. Our findings emphasize the importance of increased sleep hygiene education, especially in preparing future military officers and during military exercises. Prioritizing sleep hygiene in these ways can significantly increase soldiers' life satisfaction.

The stress of losing sleep: Sex-specific neurobiological outcomes

Sleep is a vital and evolutionarily conserved process, critical to daily functioning and homeostatic balance. Losing sleep is inherently stressful and leads to numerous detrimental physiological outcomes. Despite sleep disturbances affecting everyone, women and female rodents are often excluded or underrepresented in clinical and pre-clinical studies. Advancing our understanding of the role of biological sex in the responses to sleep loss stands to greatly improve our ability to understand and treat health consequences of insufficient sleep. As such, this review discusses sex differences in response to sleep deprivation, with a focus on the sympathetic nervous system stress response and activation of the hypothalamic-pituitary-adrenal (HPA) axis. We review sex differences in several stress-related consequences of sleep loss, including inflammation, learning and memory deficits, and mood related changes. Focusing on women's health, we discuss the effects of sleep deprivation during the peripartum period. In closing, we present neurobiological mechanisms, including the contribution of sex hormones, orexins, circadian timing systems, and astrocytic neuromodulation, that may underlie potential sex differences in sleep deprivation responses.

Intricate role of sleep deprivation in modulating depression: focusing on BDNF, VEGF, serotonin, cortisol, and TNF-α

In this review article, we aimed to discuss intricate roles of SD in modulating depression in preclinical and clinical studies. Decades of research have shown the inconsistent effects of SD on depression, focusing on SD duration. However, inconsistent role of SD seems to be more complicated, and SD duration cannot be the only one factor. Regarding this issue, we chose some important factors involved in the effects of SD on cognitive functions and mood including brain-derived neurotrophic factor (BDNF), vascular endothelial growth factor (VEGF), serotonin, cortisol, and tumor necrosis factor-alpha (TNF-α). It was concluded that SD has a wide-range of inconsistent effects on BDNF, VEGF, serotonin, and cortisol levels. It was noted that BDNF diurnal rhythm is significantly involved in the modulatory role of SD in depression. Furthermore, the important role of VEGF in blood-brain barrier permeability which is involved in modulating depression was discussed. It was also noted that there is a negative correlation between cortisol and BDNF that modulates depression. Eventually, it was concluded that TNF-α regulates sleep/wake cycle and is involved in the vulnerability to cognitive and behavioral impairments following SD. TNF-α also increases the permeability of the blood-brain barrier which is accompanied by depressive behavior. In sum, it was suggested that future studies should focus on these mechanisms/factors to better investigate the reasons behind intricate roles of SD in modulating depression.

The Relationship between Physical Activity, Sleep Quality, and Stress: A Study of Teachers during the COVID-19 Pandemic

The COVID-19 pandemic prompted chaotic changes in the daily lives of K-12 teachers, resulting in increased stress and other mental health problems. Limited evidence regarding the relationship between physical activity, sleep, and perceived stress among teachers during the COVID-19 pandemic exists. Therefore, the purpose of this study was to investigate the association between physical activity, sleep quality, and perceived psychological stress among teachers during the COVID-19 pandemic. An online survey measuring physical activity, sleep quality, and perceived psychological stress was distributed across 47 US states between September and October of 2020. Data provided by 635 teachers (mean age: 42 ± 18 years, 74.6% female) were included in the present analysis. Results suggested a negative association between physical activity and perceived psychological stress. Mediation analyses indicated that teachers engaging in high levels of physical activity were more likely to have good quality sleep and, in turn, were less likely to report high levels of perceived stress. Physical activity and sleep-related interventions could help curtail the rising levels of psychological distress amongst K-12 teachers during stressful times such as the COVID-19 pandemic. Teachers, especially those that self-report as female and/or young, report high levels of stress. These high levels of stress are a serious challenge for school districts in terms of attracting and retaining qualified teachers in K-12 classrooms.

Stress reactivity in salivary cortisol and electrocardiogram in adolescents: Investigating sleep disturbances and insomnia

This study examined the role of sleep disturbances and insomnia in the context of stress reactivity in adolescence. One-hundred and thirty-five 11-18 year olds (M_age  = 14.2 years, SD = 1.9, 52% female) completed the Trier Social Stress Test for Children. Salivary cortisol and subjective stress ratings were collected at six time points, and heart rate as well as heart rate variability were measured pre-, during and post-stress induction. Additionally, sleep disturbances and insomnia diagnosis were assessed by a self-report questionnaire and a sleep interview. Robust mixed models investigated if adolescents with compared with adolescents without (a) sleep disturbances and (b) insomnia differ regarding cortisol, heart rate, heart rate variability and psychological stress reactivity considering gender effects. The results indicated that boys with high sleep disturbances showed higher cortisol activity compared with boys with low sleep disturbances, B = 0.88, p < 0.05. Moreover, in boys with insomnia, heart rate and alpha 1 significantly differ less than in boys without insomnia. These findings support the notion of sex differences regarding the association between poor sleep and increased activity of the hypothalamic-pituitary-adrenal axis, and a less adaptable autonomic nervous system in boys in response to an experimental social stress task.

Sleep, stress and aggression: Meta-analyses investigating associations and causality

Prior research suggests that sleep is associated with increased subjective stress and aggression, but important questions remain about the typical magnitude of these relationships, as well as their potential moderators. We therefore conducted the first meta-analysis of this literature. Across 340 associational and experimental studies, significant associations were identified between sleep with both subjective stress (r = 0.307, p < .001) and aggression (r = 0.258, p < .001) in individuals from the general population, as well as between sleep with subjective stress (r = 0.425, p < .001) in individuals with sleep disorders. Experimental sleep restriction also led to increased subjective stress (g = 0.403, p = .017) and aggression (g = 0.330, p = .042). These findings suggest that poorer sleep is associated with - and leads to - heightened levels of subjective stress and aggression. These findings, and their implications, are discussed in relation to neurobiological literature, which highlights the complex interplay between metabolic activity in the brain, hormonal changes, and behavior.

Quarreling After a Sleepless Night: Preliminary Evidence of the Impact of Sleep Deprivation on Interpersonal Conflict

Although poor sleep has been found to correlate with deteriorations in romantic relationships, its causal impact on interpersonal conflict has not previously been studied. Therefore, 30 couples were randomly assigned to either a single night of total sleep deprivation or a night of normal sleep to test the effects of sleep deprivation on couples’ conflict. After the experimental night, all participants discussed a topic of recurrent conflict for 15 min. We collected pre- and post-conflict measures of cortisol, self-reports of feelings, and satisfaction with the conflictual discussion. Multilevel analyses revealed higher cortisol levels during conflict and less positive affect prior to and after the conflict for sleep-deprived couples compared to couples in the control condition. These findings provide initial evidence for a causal negative impact of sleep deprivation on couples’ conflicts.

Association of sleep disturbance with shift work, occupational stress, and musculoskeletal pain in Chinese public hospital emergency workers: A multicentre cross-sectional study

Poor sleep, which is reportedly prevalent among healthcare professionals, could lead to various detrimental consequences. This study aimed to investigate the sleep quality of individuals working in emergency departments of public hospitals in China and explore the potential factors influencing sleep disturbance. A self-administered questionnaire was completed by 7688 emergency workers from 147 public hospitals in Shandong, China. Log-binomial regression analysis was performed to explore the relationship of sleep disturbance with possible influencing factors, including individual and work characteristics, occupational stress, shift work, and musculoskeletal pain. The participants' mean Pittsburgh Sleep Quality Index score was 9.6 ± 4.8, with 5341 (69.5%, 68.2-70.7%) of them experiencing sleep disturbance. The sleep quality was poorer in doctors (10.2 ± 5.1, 71.0%, 69.0-73.0%) than in nurses (9.2 ± 4.5, 68.6%, 67.0-70.1%), and poorer in those working in secondary (9.9 ± 4.5, 70.2%, 68.0-72.3%) and tertiary (12.2 ± 4.9, 77.5%, 75.3-79.7%) hospitals than in primary hospitals (8.0 ± 4.1, 64.6%, 62.6-66.6%). High prevalence of sleep disturbance was significantly associated with shift work, occupational stress, musculoskeletal pain, fewer breaks in a work shift, and less exercise during leisure time, after adjusting for confounding variables. Sleep disturbance occurred in emergency workers in the following order: two-shift rotation > three-shift rotation > permanent night shift > permanent day shift. Emergency workers in public hospitals in China had poor sleep quality and commonly experienced musculoskeletal pain. Urgent and comprehensive measures are needed to combat these issues.

Effects of Lactococcus lactis subsp. cremoris YRC3780 daily intake on the HPA axis response to acute psychological stress in healthy Japanese men

BACKGROUND

Lactococcus lactis subsp. cremoris (YRC3780), which is isolated from kefir, has been associated with anti-allergic effects in humans. However, it remains unknown whether daily intake of YRC3780 attenuates the response to psychological stress in humans in parallel with changes to the gut microbiome. We examined the fundamental role of YRC3780 in the gut microbiome, stress response, sleep, and mental health in humans.

METHODS

Effects of daily intake of YRC3780 on the hypothalamic-pituitary-adrenal (HPA) axis response to acute psychological stress were investigated in a double-blind, placebo-controlled clinical trial involving 27 healthy young men (mean age and body mass index: 23.5 years and 21.5 kg/m²) who were randomly assigned to placebo (n = 13) or YRC3780 (n = 14) groups. The HPA axis response to acute psychological stress, the diurnal rhythm of HPA axis activity, and gut microbiome were assessed and compared between the two groups.

RESULTS

The results showed that daily intake of YRC3780 significantly lowered morning salivary cortisol levels compared with placebo. In addition, salivary cortisol levels following a social stress test significantly decreased +40 min after beginning the TSST in the YRC3780-treated group compared to placebo. There were no significant differences between the two groups in terms of actigraphy-based sleep quality, but the subjective sleep quality and mental health were significantly improved in the YRC3780-treated group compared to placebo.

CONCLUSIONS

Our study suggests that daily intake of YRC3780 improves the HPA axis response to acute psychological stress, which might be associated with a decrease in morning cortisol levels.

Psychometrics of Persian Version of the Ageism Survey Among an Iranian Older Adult Population During COVID-19 Pandemic

Background: Studies have revealed an increase in discrimination, neglect, and abuse among the older adult population during this period. This study assessed the validity and reliability of the Persian version of the ageism survey instrument tested on a sample of the Iranian older adult population during coronavirus disease (COVID-19) pandemic. An important move in counteracting ageism is to classify the ageism scale comprehensively by employing adequate psychometrics.

Methods: The Persian version of the ageism scale was developed using a two-step procedure. The first step involved translating and revising the original scale to develop a Persian version of the ageism scale. The second step involved assessing the psychometric features of the newly adapted scale using construct validity through exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) and thereafter assessing the reliability through the average inter-item correlation (AIC), Cronbach's alpha. The sample consisted of 400 older adults (age 65 and older), who were recruited through online data collection, with samples for EFA and CFA randomly selected from the total samples.

Results: The Persian version of the ageism survey has three factors: age-related deprivation with five items, dignity with three items, and employment with three items; all of which explained 57.02% of the total variance. The outcome of the EFA was verified by the CFA, with internal consistency reliability being excellent (Cronbach's alpha was 0.725, 0.698, and 0.708 for the three factors).

Conclusion: This study specifically offers a restructured three factors Persian version of the ageism survey for Iranian older adults with acceptable construct validity and reliability.

Balance of Autonomic Nervous Activity, Exercise, and Sleep Status in Older Adults: A Review of the Literature

While older people are frequently known to experience sleep disturbances, there are also many older people who have a good quality of sleep. However, little is known about the balance of autonomic nervous activity, exercise habits, and sleep status in healthy older adults. This study reviews the literature regarding balance of the autonomic nervous activity, exercise, and sleep in healthy older adults. Relevant articles were searched from electronic databases using the combination of the following keywords: "Autonomic nervous activity", "sleep status", "sleep", "healthy older adults", "aging", "heart rate variability (HRV)" and "exercise". Articles were included if they met inclusion criteria: (1) Published in English, (2) Article types: research and review articles, (3) Main outcome was related to the autonomic nervous activity, lifestyle, sleep, and/or healthy aging, and (4) Fully accessed. From 877 articles that were identified, 16 articles were included for review. Results showed that the autonomic nervous activity changes with increasing age, particularly a constant decline in cardiac vagal modulation due to the significant decrease in the nocturnal parasympathetic activity. In addition, the autonomic nervous activity was also related to sleep status and lifestyle, particularly the capability to exercise. In preparing older people toward a healthy aging, maintaining good sleep quality and exercise is suggested.

Cortisol and C-Reactive Protein Vary During Sleep Loss and Recovery but Are Not Markers of Neurobehavioral Resilience

Cortisol and C-reactive protein (CRP) typically change during total sleep deprivation (TSD) and psychological stress; however, it remains unknown whether these biological markers can differentiate robust individual differences in neurobehavioral performance and self-rated sleepiness resulting from these stressors. Additionally, little is known about cortisol and CRP recovery after TSD. In our study, 32 healthy adults (ages 27-53; mean ± SD, 35.1 ± 7.1 years; 14 females) participated in a highly controlled 5-day experiment in the Human Exploration Research Analog (HERA), a high-fidelity National Aeronautics and Space Administration (NASA) space analog isolation facility, consisting of two baseline nights, 39 h TSD, and two recovery nights. Psychological stress was induced by a modified Trier Social Stress Test (TSST) on the afternoon of TSD. Salivary cortisol and plasma CRP were obtained at six time points, before (pre-study), during [baseline, the morning of TSD (TSD AM), the afternoon of TSD (TSD PM), and recovery], and after (post-study) the experiment. A neurobehavioral test battery, including measures of behavioral attention and cognitive throughput, and a self-report measure of sleepiness, was administered 11 times. Resilient and vulnerable groups were defined by a median split on the average TSD performance or sleepiness score. Low and high pre-study cortisol and CRP were defined by a median split on respective values at pre-study. Cortisol and CRP both changed significantly across the study, with cortisol, but not CRP, increasing during TSD. During recovery, cortisol levels did not return to pre-TSD levels, whereas CRP levels did not differ from baseline. When sex was added as a between-subject factor, the time × sex interaction was significant for cortisol. Resilient and vulnerable groups did not differ in cortisol and CRP, and low and high pre-study cortisol/CRP groups did not differ on performance tasks or self-reported sleepiness. Thus, both cortisol and CRP reliably changed in a normal, healthy population as a result of sleep loss; however, cortisol and CRP were not markers of neurobehavioral resilience to TSD and stress in this study.

Are Physical Activities Associated With Perceived Stress? The Evidence From the China Health and Nutrition Survey

Psychological stress is a negative affective state. The association between physical activity and psychological stress was commonly reported in previous researches. Few published studies with large sample sizes have explored such an association in Chinese population. The current research aims to assess the association between perceived stress and physical activity preferences, as well as the association between risk of high perceived stress and physical activity behaviors (e.g., sports-, transport-, occupational-related physical activity, sedentary activities and time in bed). The data were collected from the China Health and Nutrition Survey (CHNS) in 2015. Generalized linear models and logistic regression models were used to explore the association between perceived stress and physical activity. In total, 11,066 participants were included in the current analysis. For physical activity preferences, we found that “like” preference of all six mentioned domains of activities contributed to lower perceived stress (i.e., lower perceived stress scale −14 score, all β < 0 and p < 0.05). For physical activity behaviors, the results indicated that none/low intensity physical activity behaviors (e.g., sports-, occupational- related, sedentary) were associated with risk of high perceived stress, except that low intensity of transport-related activities seemed to be protective from high stress. However, the association between intensity of physical activity behaviors and perceived stress was not simply the higher the better. High intensity of all these physical activity behaviors was also associated with high perceived stress. Our findings suggest that positive preferences and moderate physical activity behaviors were associated with low perceived stress. The findings herein highlight the effect of regulating physical activity on perceived stress, as well as inform potential strategies to reduce psychological stress.

Does insufficient sleep affect how you learn from reward or punishment? Reinforcement learning after 2 nights of sleep restriction

To learn from feedback (trial and error) is essential for all species. Insufficient sleep has been found to reduce the sensitivity to feedback as well as increase reward sensitivity. To determine whether insufficient sleep alters learning from positive and negative feedback, healthy participants (n = 32, mean age 29.0 years, 18 women) were tested once after normal sleep (8 hr time in bed for 2 nights) and once after 2 nights of sleep restriction (4 hr/night) on a probabilistic selection task where learning behaviour was evaluated in three ways: as generalised learning, short-term win-stay/lose-shift learning strategies, and trial-by-trial learning rate. Sleep restriction did not alter the sensitivity to either positive or negative feedback on generalised learning. Also, short-term win-stay/lose-shift strategies were not affected by sleep restriction. Similarly, results from computational models that assess the trial-by-trial update of stimuli value demonstrated no difference between sleep conditions after the first block. However, a slower learning rate from negative feedback when evaluating all learning blocks was found after sleep restriction. Despite a marked increase in sleepiness and slowed learning rate for negative feedback, sleep restriction did not appear to alter strategies and generalisation of learning from positive or negative feedback.

Immunization with a heat-killed bacterium, Mycobacterium vaccae NCTC 11659, prevents the development of cortical hyperarousal and a PTSD-like sleep phenotype after sleep disruption and acute stress in mice

STUDY OBJECTIVES

Sleep deprivation induces systemic inflammation that may contribute to stress vulnerability and other pathologies. We tested the hypothesis that immunization with heat-killed Mycobacterium vaccae NCTC 11659 (MV), an environmental bacterium with immunoregulatory and anti-inflammatory properties, prevents the negative impacts of 5 days of sleep disruption on stress-induced changes in sleep, behavior, and physiology in mice.

METHODS

In a 2 × 2 × 2 experimental design, male C57BL/6N mice were given injections of either MV or vehicle on days -17, -10, and -3. On days 1-5, mice were exposed to intermittent sleep disruption, whereby sleep was disrupted for 20 h per day. Immediately following sleep disruption, mice were exposed to 1-h social defeat stress or novel cage (control) conditions. Object location memory (OLM) testing was conducted 24 h after social defeat, and tissues were collected 6 days later to measure inflammatory markers. Sleep was recorded using electroencephalography (EEG) and electromyography (EMG) throughout the experiment.

RESULTS

In vehicle-treated mice, only the combination of sleep disruption followed by social defeat (double hit): (1) increased brief arousals and NREM beta (15-30 Hz) EEG power in sleep immediately post-social defeat compared to baseline; (2) induced an increase in the proportion of rapid-eye-movement (REM) sleep and number of state shifts for at least 5 days post-social defeat; and (3) induced hyperlocomotion and lack of habituation in the OLM task. Immunization with MV prevented most of these sleep and behavioral changes.

CONCLUSIONS

Immunization with MV ameliorates a stress-induced sleep and behavioral phenotype that shares features with human posttraumatic stress disorder.

Age and time-of-day differences in the hypothalamo-pituitary-testicular, and adrenal, response to total overnight sleep deprivation

STUDY OBJECTIVES

In young men, sleep restriction decreases testosterone (Te) and increases afternoon cortisol (F), leading to anabolic-catabolic imbalance, insulin resistance, and other andrological health consequences. Age-related differences in the hypothalamo-pituitary-testicular/adrenal response to sleep restriction could expose older individuals to greater or lesser risk. We aimed to evaluate and compare the 24-h and time-of-day effect of sleep restriction on F, luteinizing hormone (LH), and Te in young and older men.

METHODS

Thirty-five healthy men, aged 18-30 (n = 17) and 60-80 (n =18) years, underwent overnight sleep deprivation (complete nighttime wakefulness) or nighttime sleep (10 pm to 6 am) with concurrent 10-min blood sampling in a prospectively randomized crossover study. F, LH, and Te secretion were calculated by deconvolution analysis.

RESULTS

Sleep deprivation had multiple effects on 24-h Te secretion with significant reductions in mean concentrations, basal, total and pulsatile secretion, and pulse frequency (each p < 0.05), in the absence of detectable changes in LH. These effects were most apparent in older men and differed according to age for some parameters: pulsatile Te secretion (p = 0.03) and Te pulse frequency (p = 0.02). Time-of-day analyses revealed that sleep restriction significantly reduced Te in the morning and afternoon, reduced LH in the morning in both age groups, and increased F in the afternoon in older men.

CONCLUSIONS

These data suggest a time-of-day dependent uncoupling of the regulatory control of the testicular axis and of F secretion. Future studies will need to directly verify these regulatory possibilities specifically and separately in young and older men.

CLINICAL TRIAL

Not applicable.

Sleep Deprivation Deteriorates Heart Rate Variability and Photoplethysmography

Introduction

Sleep deprivation has deleterious effects on cardiovascular health. Using wearable health trackers, non-invasive physiological signals, such as heart rate variability (HRV), photoplethysmography (PPG), and baroreflex sensitivity (BRS) can be analyzed for detection of the effects of partial sleep deprivation on cardiovascular responses.

Methods

Fifteen participants underwent 1 week of baseline recording (BSL, usual day activity and sleep) followed by 3 days with 3 h of sleep per night (SDP), followed by 1 week of recovery with sleep ad lib (RCV). HRV was recorded using an orthostatic test every morning [root mean square of the successive differences (RMSSD), power in the low-frequency (LF) and high-frequency (HF) bands, and normalized power nLF and nHF were computed]; PPG and polysomnography (PSG) were recorded overnight. Continuous blood pressure and psychomotor vigilance task were also recorded. A questionnaire of subjective fatigue, sleepiness, and mood states was filled regularly.

Results

RMSSD and HF decreased while nLF increased during SDP, indicating a decrease in parasympathetic activity and a potential increase in sympathetic activity. PPG parameters indicated a decrease in amplitude and duration of the waveforms of the systolic and diastolic periods, which is compatible with increases in sympathetic activity and vascular tone. PSG showed a rebound of sleep duration, efficiency, and deep sleep in RCV compared to BSL. BRS remained unchanged while vigilance decreased during SDP. Questionnaires showed an increased subjective fatigue and sleepiness during SDP.

Conclusion

HRV and PPG are two markers easily measured with wearable devices and modified by partial sleep deprivation, contradictory to BRS. Both markers showed a decrease in parasympathetic activity, known as detrimental to cardiovascular health.

The effect of sleep on the salivary cortisol response to acute stressors: a review and suggestions

There have been steadily increasing studies on the relationship between sleep and stress. However, the findings regarding the effects of sleep on the acute stress response have been inconsistent. Elevated, blunted, or unchanged salivary cortisol stress response have been reported. Therefore, this study conducted a systematic review of previous studies to provide a comprehensive summary of the factors that influence the effects of sleep on the salivary cortisol stress response. We conducted a comprehensive electronic literature search in PubMed, PsycINFO, PsycARTICLES, Web of Science, MEDLINE, and EMBASE for human studies published in English (up to June 2019). Finally, 17 articles with participants aged 6.4-72 years were included in this review. We assessed the following factors: designing factors (sleep measurement, stress induction, cortisol sampling period, and time intervals between sleep measurement and the acute stress task), analyzing factors (cortisol analysis), and participants' characteristics (age, sex, and background stress levels); subsequently, we explained conflicting findings across the current literature. Further, we provide study design, analysis, and report suggestions for optimal assessment of the effects of sleep on the acute stress response. This summary of influencing factors and suggestions for future studies could help elucidate the impact of sleep on stress and advance the field.

Concussive head injury exacerbates neuropathology of sleep deprivation: Superior neuroprotection by co-administration of TiO2-nanowired cerebrolysin, alpha-melanocyte-stimulating hormone, and mesenchymal stem cells

Sleep deprivation (SD) is common in military personnel engaged in combat operations leading to brain dysfunction. Military personnel during acute or chronic SD often prone to traumatic brain injury (TBI) indicating the possibility of further exacerbating brain pathology. Several lines of evidence suggest that in both TBI and SD alpha-melanocyte-stimulating hormone (α-MSH) and brain-derived neurotrophic factor (BDNF) levels decreases in plasma and brain. Thus, a possibility exists that exogenous supplement of α-MSH and/or BDNF induces neuroprotection in SD compounded with TBI. In addition, mesenchymal stem cells (MSCs) are very portent in inducing neuroprotection in TBI. We examined the effects of concussive head injury (CHI) in SD on brain pathology. Furthermore, possible neuroprotective effects of α-MSH, MSCs and neurotrophic factors treatment were explored in a rat model of SD and CHI. Rats subjected to 48h SD with CHI exhibited higher leakage of BBB to Evans blue and radioiodine compared to identical SD or CHI alone. Brain pathology was also exacerbated in SD with CHI group as compared to SD or CHI alone together with a significant reduction in α-MSH and BDNF levels in plasma and brain and enhanced level of tumor necrosis factor-alpha (TNF-α). Exogenous administration of α-MSH (250μg/kg) together with MSCs (1×10⁶) and cerebrolysin (a balanced composition of several neurotrophic factors and active peptide fragments) (5mL/kg) significantly induced neuroprotection in SD with CHI. Interestingly, TiO₂ nanowired delivery of α-MSH (100μg), MSCs, and cerebrolysin (2.5mL/kg) induced enhanced neuroprotection with higher levels of α-MSH and BDNF and decreased the TNF-α in SD with CHI. These observations are the first to show that TiO₂ nanowired administration of α-MSH, MSCs and cerebrolysin induces superior neuroprotection following SD in CHI, not reported earlier. The clinical significance of our findings in light of the current literature is discussed.

Insight into the relationship between sleep characteristics and anxiety: A cross-sectional study in indigenous and minority populations in northeastern Greece

A cross-sectional population-based study was conducted in order to evaluate the association of sleep characteristics with anxiety disorders using self-reported questionnaires and taking into account several socio-demographic, lifestyle and health related characteristics. 957 participants between 19 and 86 years old were enrolled in our study. Anxiety symptoms were assessed using the Zung Self-rating Anxiety Scale. Participants self-reported their daily sleep habits and filled in the following scales: Epworth Sleepiness Scale, Athens Insomnia Scale, Pittsburgh Sleep Quality Index and Berlin Questionnaire. Overall prevalence of anxiety was 33.6%. Anxiety symptoms were more prominent among minority groups. Subjects with anxiety reported shorter sleep duration and reduced sleep efficiency. After adjusting for all possible confounders, they were five times more likely to exhibit short sleep duration (≤6h) and 0.60 times less likely long sleep duration (>8h). These relations remained significant in both genders, but were more pronounced among men. Moreover, anxiety was associated with excessive daytime sleepiness, insomnia, poor sleep quality and higher risk of obstructive sleep apnea (OSA). Results highlight the association of sleep disturbances with anxiety disorders and call for conduction of larger scale prospective studies in order to assess causality on the clinically important relationship between sleep characteristics and anxiety disorders.

Parsing inter- and intra-individual variability in key nervous system mechanisms of stress responsivity and across functional domains

Exposure to stressful events is omnipresent in modern human life, yet people show considerable heterogeneity in the impact of stress exposure(s) on their functionality and overall health. Encounter with stressor(s) is counteracted by an intricate repertoire of nervous-system responses. This narrative review starts with a brief summary of the vast evidence that supports heart rate variability, cortisol secretion, and large-scale cortical network interactions as kay physiological, endocrinological, and neural mechanisms of stress responsivity, respectively. The second section highlights potential sources for inter-individual variability in these mechanisms, by focusing on biological, environmental, social, habitual, and psychological factors that may influence stress responsivity patterns and thus contribute to heterogeneity in the impact of stress exposure on functionality and health. The third section introduces intra-individually variability in stress responsivity across functional domains as a novel putative source for heterogeneity in the impact of stress exposure. Challenges and future directions are further discussed. Parsing inter- and intra-individual variability in nervous-system mechanisms of stress responsivity and across functional domains is critical towards potential clinical translation.

Sleep Quality and Daytime Functioning in Older European Adults

Abstract. The aim of this article was to review research studies related to the issues of sleep in older adults, examining the relationship between sleep quality and a set of psychological variables of daytime functioning in healthy older adults: quality of life, subjective health, functional ability, cognitive function, and emotional state, in Europe. Combined scoping review search strategies resulted in a total of 84 articles selected for review. We conclude there is a considerable amount of European research on sleep quality and its correlates in older adults’ population. Studying these relationships may be the basis for the targeted planning of psychological interventions aiming at raising the quality of life in older adults. The selected domains of older adults’ everyday functioning were all well represented in the retrieved research studies.

Effects of lifestyle on physical health in Slovak university students

Overweight and obesity in childhood and young people represent a large global health problem. Therefore, the main aim of the study was to assess the prevalence of overweight/obesity by body mass index (BMI) and its associated lifestyle factors among university students in Slovakia. The BMI index was examined in relation to nine life factors for both sexes, respectively, in a sample of 200 (108 men and 92 women) young university students from Slovakia. The data were obtained using anthropometric measurements and by means of a questionnaire. The results for BMI values confirmed that both sexes were classified into the “about right” weight category. Analysis of the BMI values and questionnaire data showed different results for both sexes. While the type of daily activity and type of physical activity were associated with greater obesity for men, in women, tobacco intake was an important.

Effect of repetitive transcranial magnetic stimulation on the cognitive impairment induced by sleep deprivation: a randomized trial

OBJECTIVE

Currently, an efficient method for improving cognitive impairment due to sleep deprivation (SD) is lacking. The aim of this study is to evaluate the effect of high-frequency repetitive transcranial magnetic stimulation (rTMS) during SD on reversing the adverse effects of SD.

METHODS

A total of 66 healthy people were randomized into the rTMS group and sham group. Both groups were deprived of sleep for 24 h. During SD, participants were asked to complete several cognitive tasks and underwent mood assessments. Saliva cortisol levels, plasma concentrations of brain-derived neurotrophic factor (BDNF), precursor BDNF (proBDNF), and tissue-type plasminogen activator (tPA), and frontal blood activation were detected before and after SD. The rTMS group received real rTMS stimulation for 2 sessions of 10 Hz rTMS (40 trains of 50 pulses with a 20-second intertrain interval) to the left dorsolateral prefrontal cortex and the sham group received sham stimulation during SD.

RESULTS

Twenty-four hours of SD induced a reduced accuracy in the n-back task, increases in both anxiety and depression, increased cortisol levels, decreased frontal blood activation and decreased BDNF levels in healthy people. Notably, rTMS improved the hyperactivity of the hypothalamic-pituitary-adrenal axis and decreased frontal blood activation induced by SD, and reduced the consumption of plasma proBDNF.

CONCLUSIONS

Twenty-four hours of SD induced a cognitive impairment. The administration of high-frequency rTMS during sleep deprivation exerted positive effects on HPA axis and frontal activation and might help alleviate cognitive impairment in the long term.

Sleep, circadian rhythms and health

At the core of human thought, for the majority of individuals in the developed nations at least, there is the tacit assumption that as a species we are unfettered by the demands imposed by our biology and that we can do what we want, at whatever time we choose, whereas in reality every aspect of our physiology and behaviour is constrained by a 24 h beat arising from deep within our evolution. Our daily circadian rhythms and sleep/wake cycle allow us to function optimally in a dynamic world, adjusting our biology to the demands imposed by the day/night cycle. The themes developed in this review focus upon the growing realization that we ignore the circadian and sleep systems at our peril, and this paper considers the mechanisms that generate and regulate circadian and sleep systems; what happens mechanistically when these systems collapse as a result of societal pressures and disease; how sleep disruption and stress are linked; why sleep disruption and mental illness invariably occur together; and how individuals and employers can attempt to mitigate some of the problems associated with working against our internal temporal biology. While some of the health costs of sleep disruption can be reduced, in the short-term at least, there will always be significant negative consequences associated with shift work and sleep loss. With this in mind, society needs to address this issue and decide when the consequences of sleep disruption are justified in the workplace.

Salivary cortisol response to psychosocial stress in the late evening depends on CRHR1 genotype

The activation of the hypothalamus-pituitary-adrenal (HPA) axis is induced by stress. Imbalances in this system increase the risk of developing stress related disorders including mental illness. Variants in the single nucleotide polymorphism (SNP) rs110402 of the corticotropin-releasing hormone receptor type I (CRHR1) gene have been shown in interaction with childhood maltreatment to increase the vulnerability to develop depressive symptoms in adulthood. In this study, the direct contribution of polymorphism of the CRHR1 gene (rs110402) to the salivary cortisol response to stress independently from childhood adversity was investigated. Healthy young men between the ages of 18 and 30, free from childhood maltreatment and early trauma, were genotyped (n = 121). To increase the power of the genetic analysis, only homozygous carriers of the common C (n = 31) and of the rare T (n = 21) allele were selected for this study and exposed to a Trier Social Stress Test (TSST) in the late evening (22.30 to 22.40). Salivary samples for the assessment of cortisol and its inactive metabolite cortisone were taken early in the evening (20.00), just before (22.30) and immediately after (22.40) as well as 15 minutes after stress exposure (22.55). Participants with the TT genotype showed higher cortisol levels 15 minutes post stress compared to participants with the CC genotype. No genotype differences were found for cortisone. Interestingly, TT participants reported lower subjective perceived stress levels before the TSST, but not after stress exposure. These results confirm that variants of rs110402 in the CRHR1 gene contribute to an increased stress response. Contrary to previous findings, however, this effect could be observed in subjects reporting no exposure to childhood maltreatment or early trauma.

Sleep deprivation and stress: a reciprocal relationship

Sleep is highly conserved across evolution, suggesting vital biological functions that are yet to be fully understood. Animals and humans experiencing partial sleep restriction usually exhibit detrimental physiological responses, while total and prolonged sleep loss could lead to death. The perturbation of sleep homeostasis is usually accompanied by an increase in hypothalamic–pituitary–adrenal (HPA) axis activity, leading to a rise in circulating levels of stress hormones (e.g. cortisol in humans, corticosterone in rodents). Such hormones follow a circadian release pattern under undisturbed conditions and participate in the regulation of sleep. The investigation of the consequences of sleep deprivation, from molecular changes to behavioural alterations, has been used to study the fundamental functions of sleep. However, the reciprocal relationship between sleep and the activity of the HPA axis is problematic when investigating sleep using traditional sleep-deprivation protocols that can induce stress per se. This is especially true in studies using rodents in which sleep deprivation is achieved by exogenous, and potentially stressful, sensory–motor stimulations that can undoubtedly confuse their conclusions. While more research is needed to explore the mechanisms underlying sleep loss and health, avoiding stress as a confounding factor in sleep-deprivation studies is therefore crucial. This review examines the evidence of the intricate links between sleep and stress in the context of experimental sleep deprivation, and proposes a more sophisticated research framework for sleep-deprivation procedures that could benefit from recent progress in biotechnological tools for precise neuromodulation, such as chemogenetics and optogenetics, as well as improved automated real-time sleep-scoring algorithms.

Association of naturally occurring sleep loss with reduced amygdala resting-state functional connectivity following psychosocial stress

Enduring sleep loss is a risk factor for a variety of both somatic and mental health issues. When subjected to sleep loss, the brain becomes vulnerable to critical alterations in cognitive and emotional processing. In our study, we examined the effect of psychosocial stress on amygdala resting-state functional connectivity in participants with cumulative sleep loss calculated across the seven days preceding scanning. For this purpose, forty-five healthy male participants completed a one-week sleep diary and underwent resting-state scans before and after taking part in the ScanSTRESS paradigm, which allows social stress induction during functional magnetic resonance imaging. Sleep loss was negatively associated with seed-based functional connectivity of the left amygdala with the medial prefrontal cortex, dorsal anterior cingulate cortex, anterior insula, posterior cingulate cortex, and dorsolateral prefrontal cortex. That is, participants with higher amounts of sleep loss showed reduced left amygdala connectivity after social stress induction to cortical regions encompassing main nodes of the brain's default mode network and salience network. Our results shed more light on how brain functional connectivity may shape the brain's stress response in the context of naturally occurring sleep loss, revealing a potential neural mechanism for increased vulnerability to stress-related psychopathology.

Effects of Mongolian Warm Acupuncture on iNOS/NO and Inflammatory Cytokines in the Hippocampus of Chronic Fatigue Rats

The inducible nitric oxide synthase/nitric oxide (iNOS/NO) signaling pathway and inflammatory cytokines play important roles in the pathogenesis of exercise-induced fatigue. Studies have found that Mongolian warm acupuncture (WA) could alleviate exercise-induced fatigue. However, the exact mechanisms underlying its effects remain unclear. In the present study, we investigated the effects of Mongolian WA on iNOS/NO signaling pathway and proinflammatory cytokines in a chronic exhaustive swimming-induced fatigue rat model. Animals were randomly divided into Control group, Ctrl + WA group, Model group, and Model + WA group. The body weight, exhaustive swimming time test, and Morris water maze test were performed before and after the chronic exhaustive swimming. The serum levels of interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), and iNOS were detected by enzyme linked immunosorbent assay (ELISA). The mRNA expressions of IL-1β, IL-6, TNF-α, IFN-γ, and iNOS in the hippocampus were measured by real-time polymerase chain reaction (RT-PCR). Moreover, the protein expression of iNOS in the hippocampus was measured by western blot, and the NO productions in the serum and hippocampus were detected by Griess reaction system. Chronic exhaustive exercise significantly reduced the body weight and exhaustive swimming time, and induced impairment in learning and memory, and which were reversed by WA treatment. Chronic exhaustive exercise also increased the expressions of iNOS and proinflammatory cytokines, while WA treatment significantly decreased the level of iNOS and proinflammatory cytokines. However, chronic exhaustive exercise did not affect the NO production. These findings demonstrated that WA could alleviate the chronic exhaustive swimming-induced fatigue and improve the learning and memory ability, and the actions might be related to the reduction of inflammatory response and iNOS expression.

Reciprocal relations between work stress and insomnia symptoms: A prospective study

Work stress and poor sleep are closely related in cross-sectional data, but evidence from prospective data is limited. We analysed how perceived stress and work stressors (work demands, decision authority and workplace social support) are related to key dimensions of insomnia over time, using structural equation modelling. Biennial measurements from a large sample of the working population in Sweden enabled us to analyse both the relationship from stress to sleep as well as that from sleep to stress. Overall, we found reciprocal relations between insomnia and all four stress measures. However, looking at the relation between each dimension of insomnia and each stress measure, there were some differences in direction of effects. In the direction from stress to sleep, all work stressors as well as perceived stress predicted both difficulties initiating sleep and difficulties maintaining sleep. The same was found for non-restorative sleep, with the exception for decision authority. In the opposite direction, difficulties maintaining sleep predicted increased levels of work demands and perceived stress. Difficulties initiating sleep stood out among the insomnia symptoms as not predicting any of the stress measures, while non-restorative sleep was the only symptom predicting all stress measures. The results advance the understanding of the stress-sleep relationship and indicate a potential vicious circle between insomnia and perceived stress as well as work stressors, suggesting that the workplace could be an arena for interventions to alleviate insomnia.

Sleep Predicts Collegiate Academic Performance: Implications for Equity in Student Retention and Success

College students show high levels of insufficient sleep, excessive daytime sleepiness, sleep schedule irregularity, poor sleep quality, and inadequate sleep hygiene. This article describes the evidence linking poor sleep with impaired academic performance; discusses mediating environmental, behavioral, and demographic factors that correlate with sleep; and highlights examples of successful health promotion initiatives on college campuses. Given that students who are traditionally minoritized on college campuses tend to have worse sleep, improving sleep health emerges as an important issue for retention, equity, and inclusion.

Sleep problems are a strong predictor of stress-related metabolic changes in police officers. A prospective study

OBJECTIVE

Previous studies have shown that workers chronically exposed to occupational stress have an increased risk of metabolic syndrome (MetS) and sleep problems (SPs). The purpose of this study was to verify whether SPs mediate the relationship between stress and MetS.

METHOD

A 5-year prospective cohort study included 242 police officers from a rapid response unit engaged exclusively in maintaining law and order. Perceived stress levels were measured repeatedly with the demand-control-support and the effort-reward-imbalance questionnaires; insomnia symptoms were assessed with the Pittsburgh Sleep Quality Index; excessive daytime sleepiness was measured using the Epworth Sleepiness Scale. MetS and its components were evaluated at baseline and at follow-up.

RESULTS

During 5-year follow-up period, 26 new cases of MetS were identified. Both occupational stress and SPs were significantly related to incident cases of MetS. Insomnia symptoms showed a highly significant association with MetS (aOR 11.038; CI95% 2.867-42.493). Mediation analysis confirmed that SPs mediate the relationship between stress and MetS. A reciprocal relationship was found between job stress and SPs. Work-related stress was a significant predictor of insomnia symptoms, short sleep duration, sleep dissatisfaction, and sleepiness. Compared to the reference group, police officers with SPs at baseline had significantly higher odds of reporting high stress at follow-up.

CONCLUSION

SPs play a mediating role in the relationship between occupational stress and MetS. Prevention of MetS must include the control of stress factors and an increase in the resilience of workers, but correct sleep hygiene is also an essential factor.

Efficacy Comparison of Different Acupuncture Treatments for Primary Insomnia: A Bayesian Analysis

BACKGROUND

Acupuncture treatments are used frequently in the treatment of primary insomnia considering its less side effect. However, most treatment choices are made just based on personal experience among different forms of acupuncture. This study compared the effectiveness of different forms of acupuncture for primary insomnia by using network meta-analysis.

METHODS

All randomized controlled trials (RCTs) of acupuncture treatments for primary insomnia were searched in seven databases from the date of database inception to January 6, 2019, including PubMed, Web of Science, Embase, Cochrane Library, Wanfang database, China National Knowledge Infrastructure (CNKI) database, and VIP Chinese Science and Technique Journals (CQVIP) database. After screening, the effectiveness rate was extracted from the included RCTs as primary outcomes. The network meta-analysis was performed by Review Manager 5.3, Stata13.0, and GeMTC 0.14.3.

RESULTS

Forty-two studies were included, which contained 3304 participants among 6 interventions. Based on the ranking probability and compared to western medicine, scalp acupuncture (OR = 8.12, 95% CI (4.07,16.81)) is considered to be the most effective method, followed by electroacupuncture (OR = 6.29, 95% CI (3.36, 12.67)), electroacupuncture combined scalp acupuncture (OR = 5.20, 95% CI (2.43,11.28)), warm acupuncture (OR = 3.79, 95% CI (1.85,8.16)), and conventional acupuncture (OR = 2.86, 95% CI (2.05,3.95)). There was no significant difference between the results of direct and indirect comparisons.

CONCLUSIONS

The finding indicated that five acupuncture methods may be all effective in the treatment of primary insomnia, and scalp acupuncture seems to be the best treatment. However, the overall quality of the included trials could only be ranked as medium to low quality, and higher quality RCTs are warranted for sufficient evidence.

HPA axis responses to psychological challenge linking stress and disease: What do we know on sources of intra- and interindividual variability?

Stress is an ubiquitous phenomenon with significant impact on human physiology when it lasts too long, when it is too intense, or when it hits vulnerable individuals. Examining the mechanisms linking stress exposure with health and disease is an important endeavor in psychoneuroendocrine research. Empirical evidence so far revealed large intra- as well as inter-individual variability in hypothalamic-pituitary-adrenal (HPA) axis responses to acute psychosocial stress, showing that the HPA axis is a highly adaptive system. Thus, the characterization of intra- und inter-individual patterns of HPA axis reactivity is of high scientific interest and forms the basis on which mechanistic links between stress response (dys)regulation and health impairments can be examined. To date, basic knowledge has been, and still is, accumulated on demographic, biological (including genetic and epigenetic) factors, lifestyle behavioral variables, consumption of substances and medication, psychological and personality factors, as well as on methodological aspects. Besides this, there is also very recent progress in respect to the development of laboratory stress paradigms that can be applied in virtual reality or inside an MRI-scanner. In sum, the present review updates our current knowledge on moderating and intervening factors as sources of intra- und inter-individual variability in human cortisol stress responses and offers recommendations for future research designs.

Positivity Effect and Working Memory Performance Remains Intact in Older Adults After Sleep Deprivation

Background: Older adults perform better in tasks which include positive stimuli, referred to as the positivity effect. However, recent research suggests that the positivity effect could be attenuated when additional challenges such as stress or cognitive demands are introduced. Moreover, it is well established that older adults are relatively resilient to many of the adverse effects of sleep deprivation. Our aim was to investigate if the positivity effect in older adults is affected by one night of total sleep deprivation using an emotional working memory task. Methods: A healthy sample of 48 older adults (60-72 years) was either sleep deprived for one night (n = 24) or had a normal night's sleep (n = 24). They performed an emotional working memory n-back (n = 1 and 3) task containing positive, negative and neutral pictures. Results: Performance in terms of accuracy and reaction times was best for positive stimuli and worst for negative stimuli. This positivity effect was not altered by sleep deprivation. Results also showed that, despite significantly increased sleepiness, there was no effect of sleep deprivation on working memory performance. A working memory load × valence interaction on the reaction times revealed that the beneficial effect of positive stimuli was only present in the 1-back condition. Conclusion: While the positivity effect and general working memory abilities in older adults are intact after one night of sleep deprivation, increased cognitive demand attenuates the positivity effect on working memory speed.

Sleep deprivation and its effects on communication during individual and collaborative tasks

Sleep loss has been shown to cause impairments in a number of aspects central for successful communication, ranging from poorer linguistic comprehension to alterations in speech prosody. However, the effect of sleep loss on actual communication is unknown. This study investigated how a night of sleep deprivation affected performance during multiple tasks designed to test verbal communication. Healthy participants (N = 183) spent 8–9 hours per night in bed for three nights and were then randomised to either one night of total sleep deprivation or a fourth night with 8–9 hours in bed. The following day, participants completed two tasks together with another participant: a model-building task and a word-description task. Differences in performance of these tasks were assessed alongside speaking duration, speaking volume, and speaking volume consistency. Additionally, participants individually completed a verbal fluency assessment. Performance on the model-building task was worse if the model-builder was sleep deprived, whereas sleep deprivation in the instruction-giver predicted an improvement. Word-description, verbal fluency, speech duration, speaking volume, and speaking volume consistency were not affected. The results suggest that sleep deprivation leads to changes in communicative performance during instructive tasks, while simpler word-description tasks appear resilient.

Mood impairment is stronger in young than in older adults after sleep deprivation

Sleep deprivation commonly impairs affective regulation and causes worse mood. However, the majority of previous research concerns young adults. Because susceptibility to sleep deprivation and emotion regulation change distinctively across adult age, we tested here the hypothesis that the effect of sleep deprivation on mood is stronger in young than in older adults. In an experimental design, young (18–30 years) and older adults (60–72 years) participated in either a sleep control (young, n = 63; older, n = 47) or a total sleep deprivation condition (young, n = 61; older, n = 47). Sleepiness, mood and common symptoms of sleep deprivation were measured using established questionnaires and ratings. Sleep‐deprived participants felt more sleepy, stressed and cold, and reported lower vigour and positive affect, regardless of age. All the other outcome measures (negative affect, depression, confusion, tension, anger, fatigue, total mood disturbance, hunger, cognitive attenuation, irritability) showed a weaker response to sleep deprivation in the older group, as indicated by age*sleep deprivation interactions (ps < 0.05). The results show that older adults are emotionally less affected by sleep deprivation than young adults. This tolerance was mainly related to an attenuated increase in negative mood. This could possibly be related to the well‐known positivity effect, which suggests that older adults prioritize regulating their emotions to optimize well‐being. The results also highlight that caution is warranted when generalizing results from sleep deprivation studies across the adult lifespan.

Effect of sleep deprivation on emotional working memory

The emotional dysregulation and impaired working memory found after sleep loss can have severe implications for our daily functioning. Considering the intertwined relationship between emotion and cognition in stimuli processing, there could be further implications of sleep deprivation in high‐complex emotional situations. Although studied separately, this interaction between emotion and cognitive processes has been neglected in sleep research. The aim of the present study was to investigate the effect of 1 night of sleep deprivation on emotional working memory. Sixty‐one healthy participants (mean age: 23.4 years) were either sleep deprived for 1 night (n = 30) or had a normal night’s sleep (n = 31). They performed an N‐back task with two levels of working memory load (1‐back and 3‐back) using positive, neutral and negative picture scenes. Sleep deprivation, compared with full night sleep, impaired emotional working memory accuracy, but not reaction times. The sleep‐deprived participants, but not the controls, responded faster to positive than to negative and neutral pictures. The effect of sleep deprivation was similar for both high and low working memory loads. The results showed that although detrimental in terms of accuracy, sleep deprivation did not impair working memory speed. In fact, our findings indicate that positive stimuli may facilitate working memory processing speed after sleep deprivation.

Association of Stress and Musculoskeletal Pain With Poor Sleep: Cross-Sectional Study Among 3,600 Hospital Workers

Background: While acute stress and pain are part of our inherent survival mechanisms, persistent stress and pain can negatively impact health and well-being. This may also lead to poor sleep and thus a lack of recovery. This study investigated the influence of stress and musculoskeletal pain on sleep quality. Methods: A total of 3,593 Danish hospital workers replied to a questionnaire about work and health. Pain intensity was evaluated using subjective values as an average of 9 body parts. Stress was assessed using the full version of Cohen's Perceived Stress scale. Sleep quality was rated using 3 questions on sleep characteristics. Associations between stress and pain (mutually adjusted predictors) and sleep (outcome) were modeled using binary logistic regression controlling for gender, age, education, BMI and smoking. Results: The risk ratio of moderate stress (compared to no/low stress) on poor sleep was 1.27 (CI 1.26-1.29), whereas the risk ratio of high stress on poor sleep was 1.87 (CI 1.83-1.91). Similarly, for pain, the risk ratio of moderate pain (compared to no/low pain) on poor sleep was 1.18 (95% CI 1.16-1.19), whereas the risk ratio of a high pain score on poor sleep was 1.48 (95% CI 1.44-1.52). Conclusion: This study demonstrates that both stress and musculoskeletal pain are associated with poor sleep among hospital workers. Hospital management should consider implementing strategies for preventing stress and musculoskeletal pain to improve the overall health and workability among hospital workers.