[Consequences of chronodisruption on body weight regulation and metabolism]. / Konsequenzen von Chronodisruption auf Körpergewichtsregulation und Stoffwechsel.

INTRODUCTION: The prevalence of overweight and obesity has increased dramatically. At the same time, lack of sleep has become a part of the modern lifestyle, as well as shift and night work. As a result, chronodisruption, i. e. a change in physiological processes that are controlled by the internal clock, becomes commonplace. Epidemiological data show that too short but also too long sleep are associated with an increased risk of obesity, also seen for night shift work. Overweight and obesity are associated with metabolic syndrome and data likewise report an increased risk by both short and long sleep. It has not yet been conclusively clarified how chronodisruption influences the metabolic risks. Clinical experimental studies report on neuroendocrine and circadian mechanisms and it has been shown that lack of sleep increases the hunger-promoting hormone ghrelin as well as subjective feelings of hunger and increases leptin levels. Lack of sleep also increases hedonic hunger and food-related reward signals. Through preventive measures, chronodisruption and thus, the risk of obesity can be counteracted. The extent to which smartwatches and fitness trackers, which according to the manufacturer can measure and analyze sleep, provide an objective picture of sleep has not been sufficiently investigated. However, smartwatches and fitness trackers can - probably - increase awareness of sleep in the modern society.

Assessment and management of sleep disorders in shift workers: Challenges and considerations for general practice.

BACKGROUND: Shift work is characterised by displaced sleep opportunities and associated sleep disturbance. Shift workers often report sleepiness and other wake time symptoms associated with poor sleep. However, clinical sleep disorders are also prevalent in shift workers. Although prevalence rates are similar or higher in shift workers compared with the general population, help seeking in shift workers with sleep disorders is low. OBJECTIVE: This article aims to provide general practitioners with a contemporary overview of the prevalence rates for sleep disorders in shift workers, to clarify the existing evidence relating to mental and physical health consequences of sleep disorders in shift workers and to highlight the need to consider undiagnosed sleep disorders before attributing sleep-related symptoms solely to work schedules. DISCUSSION: Symptoms of sleep loss associated with shift work overlap with symptoms experienced by individuals living with sleep disorders. Although >40% of middle-aged Australians live with a sleep disorder that requires investigation and management, symptoms in shift workers are often attributed to the work schedule and, as a result, might not be investigated for appropriate diagnosis and treatment. We argue that screening for sleep disorders in shift workers with sleep complaints should be a priority.

Light, sleep and circadian rhythm in critical illness.

PURPOSE OF REVIEW: Sleep and circadian disruption (SCD) are associated with worse outcomes in the ICU population. We discuss sleep, circadian physiology, the role of light in circadian entrainment and its possible role in treating SCD, with special attention to the use of light therapies and ICU design. RECENT FINDINGS: The American Thoracic Society recently published an official research statement highlighting key areas required to define and treat ICU SCD. Recent literature has been predominantly observational, describing how both critical illness and the ICU environment might impair normal sleep and impact circadian rhythm. Emerging consensus guidance outlines the need for standardized light metrics in clinical trials investigating effects of light therapies. A recent proof-of-concept randomized controlled trial (RCT) showed improvement in delirium incidence and circadian alignment from ICU room redesign that included a dynamic lighting system (DLS). SUMMARY: Further investigation is needed to define the optimal physical properties of light therapy in the ICU environment as well as timing and duration of light treatments. Work in this area will inform future circadian-promoting design, as well as multicomponent nonpharmacological protocols, to mitigate ICU SCD with the objective of improving patient outcomes.

Circadian Disruption in Civilian Airline Pilots.

INTRODUCTION: Most airline pilots reported having suffered from sleep disorders and fatigue due to circadian disruption, a potential risk to flight safety. This study attempted to uncover the actual scenario of circadian disruption and working load status among airline pilots.METHODS: In study 1, 21 pilots were invited to participate in a 14-d sleep monitoring and a dual 2-back test to monitor their sleep patterns and cognitive function level. To provide an in-depth view, data from scheduled flights, including 567 airline pilots, was analyzed in Study 2. The present study used cluster analysis to reflect the distribution of the flight scheduling characteristics, including working time and actual working hours. A simulation model was then developed to predict the pilots' 1-mo sleep-wake pattern.RESULTS: The results indicated that sleep problems were prevalent in this population, especially the night before an earlier morning shift. Regarding the cognitive test, they scored the lowest on earlier morning shifts compared with daytime and evening shifts. It was found that over 70% of the flight schedules can lead to circadian disruption, and 47.44% of the pilots worked under high-load status.DISCUSSION: Airline pilots inevitably work irregular hours and the current policies for coping with circadian disruption seem inefficient. This study thus calls for urgency in improving scheduling and fatigue management systems from the circadian rhythm perspective.Yang SX, Cheng S, Sun Y, Tang X, Huang Z. Circadian disruption in civilian airline pilots. Aerosp Med Hum Perform. 2024; 95(7):381-389.

Long-term night-shift work is associated with accelerates brain aging and worsens N3 sleep in female nurses.

BACKGROUND: Shift work disrupts circadian rhythms and alters sleep patterns, resulting in various health problems. To quantitatively assess the impact of shift work on brain health, we evaluated the brain age index (BAI) derived from sleep electroencephalography (EEG) results in night-shift workers and compared it with that in daytime workers. METHODS: We studied 45 female night shift nurses (mean age: 28.2 ± 3.3 years) and 44 female daytime workers (30.5 ± 4.7 years). Sleep EEG data were analyzed to calculate BAI. The BAI of night shift workers who were asleep during the daytime with those of daytime workers who were asleep at night were statistically compared to explore associations between BAI, duration of shift work, and sleep quality. RESULTS: Night-shift workers exhibited significantly higher BAI (2.14 ± 6.04 vs. 0 ± 5.35), suggesting accelerated brain aging and altered sleep architecture, including reduced delta and sigma wave frequency activity during non-rapid eye movement sleep than daytime workers. Furthermore, poor deep sleep quality, indicated by a higher percentage of N1, lower percentage of N3, and higher arousal index, was associated with increased BAI among shift workers. Additionally, a longer duration of night-shift work was correlated with increased BAI, particularly in older shift workers. CONCLUSION: Night-shift work, especially over extended periods, may be associated with accelerated brain aging, as indicated by higher BAI and alterations in sleep architecture. Interventions are necessary to mitigate the health impacts of shift work. Further research on the long-term effects and potential strategies for sleep improvement and mitigating brain aging in shift workers is warranted.

Impact of sleep disturbance in shift workers on hippocampal volume and psychomotor speed.

STUDY OBJECTIVES: Shift work interferes with circadian rhythms, affecting sleep quality and cognitive function. Poor sleep quality in shift worker (SW)s can impair psychomotor performance due to fatigue and sleepiness, increasing the risk of errors, accidents, and reduced productivity. Given the potential for atrophic changes in the hippocampus due to sleep disturbances, our study investigates how poor sleep quality correlates with hippocampal structural alterations and impacts psychomotor performance among SWs. METHODS: We recruited 100 SWs, classifying them based on sleep quality into two groups: good sleep-SW group (n = 59) and poor sleep-SW group (n = 41). Sleep quality was assessed using both 7-day actigraphy for sleep efficiency and the Pittsburgh Sleep Quality Index. A control group of 106 non-SWs without sleep problems (non-SW group) was also included for comparison. The outcome measures were psychomotor speed and hippocampal volumes, both total and by subfield. RESULTS: The poor sleep-SW group showed significantly smaller hippocampal volumes than both the good sleep-SW group (p < .001) and the non-SW group (p = .003). Longer shift work years correlated with greater reductions in hippocampal volume in this group (r = -0.42, p = .009), unlike in the good sleep-SW group (r = 0.08, p = .541). Furthermore, they demonstrated declines in psychomotor speed relative to the non-SW group (p = .006), which correlated with smaller hippocampal volumes (r = 0.37, p = .020). CONCLUSIONS: SWs with poor sleep quality exhibit significant hippocampal volume reductions and psychomotor speed decline, underscoring the importance of early intervention and support for sleep issues in this population.

Sex Differences in Insomnia and Circadian Rhythm Disorders: A Systematic Review.

Insomnia and circadian rhythm disorders are increasingly common in modern society and lead to significant challenges for people's health and well-being. Some studies suggests that men and women differ in neurohormonal secretion, biological processes, and brain morphology. Thus, such differences may affect the etiology, manifestation, and course of sleep disorders, including insomnia and circadian rhythm. This systematic review aims to synthesize the existing literature on sex differences in insomnia and circadian rhythm disorders. PubMed, MEDLINE, Epistemonikos, and Cochrane databases were searched for articles published from inception until 5 September 2023, not older than five years. We performed a systematic search using MESH and non-MESH queries: (sex differences) or (male and female differences) or (men and women differences) or (men and women) AND (insomnia) or (sleep wake disorder*) or (sleep wake rhythm disorder*) or (circadian rhythm disorder*) or (sleep cycle disruption) or (sleep cycle disorder*). Out off 2833 articles screened, 11 studies were included. The prevalence of insomnia is higher among women, and their sleep is more regular and stable compared to men. Studies evaluating the impact of the stressful situation associated with the lockdown on women's and men's insomnia present discordant results concerning sex differences. Women's circadian rhythm was found to be more stable and less fragmented than men's. However, the progression of peak activity time with age was more pronounced in men. The current literature suggests that risk factors for insomnia and circadian rhythm disorders affect men and women differently. These include cerebrovascular and cardiometabolic factors, shift work, and infections. The long-term effects of insomnia seem to be more relevant for the male sex, shortening lifespan more than in women. By summarizing and analyzing existing studies, we highlight the need for further research to improve understanding of the interaction between sex and sleep.

Immune-mediated denervation of the pineal gland underlies sleep disturbance in cardiac disease.

Disruption of the physiologic sleep-wake cycle and low melatonin levels frequently accompany cardiac disease, yet the underlying mechanism has remained enigmatic. Immunostaining of sympathetic axons in optically cleared pineal glands from humans and mice with cardiac disease revealed their substantial denervation compared with controls. Spatial, single-cell, nuclear, and bulk RNA sequencing traced this defect back to the superior cervical ganglia (SCG), which responded to cardiac disease with accumulation of inflammatory macrophages, fibrosis, and the selective loss of pineal gland-innervating neurons. Depletion of macrophages in the SCG prevented disease-associated denervation of the pineal gland and restored physiological melatonin secretion. Our data identify the mechanism by which diurnal rhythmicity in cardiac disease is disturbed and suggest a target for therapeutic intervention.

Heart failure causes sleepless nights.

Cardiac dysfunction triggers immune-mediated loss of pineal gland melatonin release.

Circadian gene × environment perturbations influence alcohol drinking in Cryptochrome-deficient mice.

Alcohol use disorder (AUD) is a widespread addiction disorder with severe consequences for health. AUD patients often suffer from sleep disturbances and irregular daily patterns. Conversely, disruptions of circadian rhythms are considered a risk factor for AUD and alcohol relapses. In this study, we investigated the extent to which circadian genetic and environmental disruptions and their interaction alter alcohol drinking behaviour in mice. As a model of genetic circadian disruption, we used Cryptochrome1/2-deficient (Cry1/2-/- ) mice with strongly suppressed circadian rhythms and found that they exhibit significantly reduced preference for alcohol but increased incentive motivation to obtain it. Similarly, we found that low circadian SCN amplitude correlates with reduced alcohol preference in WT mice. Moreover, we show that the low alcohol preference of Cry1/2-/- mice concurs with high corticosterone and low levels of the orexin precursor prepro-orexin and that WT and Cry1/2-/- mice respond differently to alcohol withdrawal. As a model of environmentally induced disruption of circadian rhythms, we exposed mice to a "shift work" light/dark regimen, which also leads to a reduction in their alcohol preference. Interestingly, this effect is even more pronounced when genetic and environmental circadian perturbations interact in Cry1/2-/- mice under "shift work" conditions. In conclusion, our study demonstrates that in mice, disturbances in circadian rhythms have pronounced effects on alcohol consumption as well as on physiological factors and other behaviours associated with AUD and that the interaction between circadian genetic and environmental disturbances further alters alcohol consumption behaviour.

Nurses' experiences and preferences around shift patterns: A scoping review.

OBJECTIVE: To explore the evidence on nurses' experiences and preferences around shift patterns in the international literature. DATA SOURCES: Electronic databases (CINHAL, MEDLINE and Scopus) were searched to identify primary studies up to April 2021. METHODS: Papers reporting qualitative or quantitative studies exploring the subjective experience and/or preferences of nurses around shift patterns were considered, with no restrictions on methods, date or setting. Key study features were extracted including setting, design and results. Findings were organised thematically by key features of shift work. RESULTS: 30 relevant papers were published between 1993 and 2021. They contained mostly qualitative studies where nurses reflected on their experience and preferences around shift patterns. The studies reported on three major aspects of shift work: shift work per se (i.e. the mere fact of working shift), shift length, and time of shift. Across all three aspects of shift work, nurses strive to deliver high quality of care despite facing intense working conditions, experiencing physical and mental fatigue or exhaustion. Preference for or adaptation to a specific shift pattern is facilitated when nurses are consulted before its implementation or have a certain autonomy to self-roster. Days off work tend to mitigate the adverse effects of working (short, long, early or night) shifts. How shift work and patterns impact on experiences and preferences seems to also vary according to nurses' personal characteristics and circumstances (e.g. age, caring responsibilities, years of experience). CONCLUSIONS: Shift patterns are often organised in ways that are detrimental to nurses' health and wellbeing, their job performance, and the patient care they provide. Further research should explore the extent to which nurses' preferences are considered when choosing or being imposed shift work patterns. Research should also strive to better describe and address the constraints nurses face when it comes to choice around shift patterns.

Human circadian variations.

Circadian rhythms, present in most phyla across life, are biological oscillations occurring on a daily cycle. Since the discovery of their molecular foundations in model organisms, many inputs that modify this tightly controlled system in humans have been identified. Polygenic variations and environmental factors influence each person's circadian rhythm, contributing to the trait known as chronotype, which manifests as the degree of morning or evening preference in an individual. Despite normal variation in chronotype, much of society operates on a "one size fits all" schedule that can be difficult to adjust to, especially for certain individuals whose endogenous circadian phase is extremely advanced or delayed. This is a public health concern, as phase misalignment in humans is associated with a number of adverse health outcomes. Additionally, modern technology (such as electric lights and computer, tablet, and phone screens that emit blue light) and lifestyles (such as shift or irregular work schedules) are disrupting circadian consistency in an increasing number of people. Though medical and lifestyle interventions can alleviate some of these issues, growing research on endogenous circadian variability and sensitivity suggests that broader social changes may be necessary to minimize the impact of circadian misalignment on health.

Demographic, psychological, chronobiological, and work-related predictors of sleep disturbances during the COVID-19 lockdown in Italy.

The first COVID-19 contagion wave caused unprecedented restraining measures worldwide. In Italy, a period of generalized lockdown involving home confinement of the entire population was imposed for almost two months (9 March-3 May 2020). The present is the most extensive investigation aimed to unravel the demographic, psychological, chronobiological, and work-related predictors of sleep disturbances throughout the pandemic emergency. A total of 13,989 Italians completed a web-based survey during the confinement period (25 March-3 May). We collected demographic and lockdown-related work changes information, and we evaluated sleep quality, insomnia and depression symptoms, chronotype, perceived stress, and anxiety using validated questionnaires. The majority of the respondents reported a negative impact of confinement on their sleep and a delayed sleep phase. We highlighted an alarming prevalence of sleep disturbances during the lockdown. Main predictors of sleep disturbances identified by regression models were: female gender, advanced age, being a healthcare worker, living in southern Italy, confinement duration, and a higher level of depression, stress, and anxiety. The evening chronotype emerged as a vulnerability factor, while morning-type individuals showed a lower predisposition to sleep and psychological problems. Finally, working from home was associated with less severe sleep disturbances. Besides confirming the role of specific demographic and psychological factors in developing sleep disorders during the COVID-19 pandemic, we propose that circadian typologies could react differently to a particular period of reduced social jetlag. Moreover, our results suggest that working from home could play a protective role against the development of sleep disturbances during the current pandemic emergency.

Deciphering the Interacting Mechanisms of Circadian Disruption and Alzheimer's Disease.

Alzheimer's disease (AD) is one of the crucial causative factors for progressive dementia. Neuropathologically, AD is characterized by the extracellular accumulation of amyloid beta plaques and intracellular neurofibrillary tangles in cortical and limbic regions of the human brain. The circadian system is one of the many affected physiological processes in AD, the dysfunction of which may reflect in the irregularity of the sleep/wake cycle. The interplay of circadian and sleep disturbances inducing AD progression is bidirectional. Sleep-associated pathological alterations are frequently evident in AD. Understanding the interrelation between circadian disruption and AD may allow for earlier identification of AD pathogenesis as well as better suited approaches and potential therapies to combat dementia. In this article, we examine the existing literature related to the molecular mechanisms of the circadian clock and interacting mechanisms of circadian disruption and AD pathogenesis.

Effects of work organization on the occurrence and resolution of sleep disturbances among night shift workers: a longitudinal observational study.

This study aimed to investigate the association between work organization and the trajectories of insomnia patterns among night shift workers in a hospital. The health examination data of hospital workers, recorded from January 2014 to December 2018, were collected; 6765 records of 2615 night shift workers were included. Insomnia was defined as a score of ≥ 15 on the Insomnia Severity Index (ISI). Participants were categorized into five groups according to insomnia patterns derived from the analysis of their ISI scores. Work organization and socio-demographic characteristics were also investigated. Generalized estimating equation models and linear mixed models were constructed to analyze the longitudinal data. Of the total participants, 53.0% reported insomnia at least once during the follow-up period. The lack of nap opportunities and work-time control was associated with the occurrence of insomnia, whereas more than 5 years of shift work experience was related to the resolution of insomnia. All work-related factors were significantly related to insomnia risk; however, the effects were not significant in the sustained insomnia group. Although sleep problems are inevitable in night shift workers, well-designed work schedules and better work organization can help reduce the occurrence of insomnia among them.

A field investigation of the relationship between rotating shifts, sleep, mental health and physical activity of Australian paramedics.

Paramedics working on a rotating shift are at an increased risk of developing chronic health issues due to continuous circadian rhythm disruption. The acute effects of shift rotation and objectively measured sleep have rarely been reported in paramedics. This study investigated the relationships between a rotating shift schedule and sleep (using actigraphy), subjective reports of sleepiness, mood, stress and fatigue. Galvanic Skin Response, energy expenditure and physical activity (BodyMedia SenseWear Armband) were also recorded across the shift schedule. Paramedics were monitored for a period of eight consecutive days across pre-shift, day shift, night shift, and 2 days off. Fifteen paramedics (M age = 39.5 and SD = 10.7 years) who worked rotational shifts experienced sleep restriction during night shift compared to pre-shift, day shift and days off (p < 0.001). Night shift was also associated with higher levels of stress (p < 0.05), fatigue (p < 0.05), and sleepiness (p < 0.05). One day off was related to a return to pre-shift functioning. Such shift-related issues have a compounding negative impact on an already stressful occupation with high rates of physical and mental health issues. Therefore, there is an urgent need to investigate methods to reduce rotating shift burden on the health of paramedics. This could be through further research aimed at providing recommendations for shift work schedules with sufficient periods for sleep and recovery from stress.

Disrupted nocturnal melatonin in autism: Association with tumor necrosis factor and sleep disturbances.

Sleep disturbances, abnormal melatonin secretion, and increased inflammation are aspects of autism spectrum disorder (ASD) pathophysiology. The present study evaluated the daily urinary 6-sulfatoxymelatonin (aMT6s) excretion profile and the salivary levels of tumor necrosis factor (TNF) and interleukin-6 (IL-6) in 20 controls and 20 ASD participants, as well as correlating these measures with sleep disturbances. Although 60% of ASD participants showed a significant night-time rise in aMT6s excretion, this rise was significantly attenuated, compared to controls (P < .05). The remaining 40% of ASD individuals showed no significant increase in nocturnal aMT6s. ASD individuals showed higher nocturnal levels of saliva TNF, but not IL-6. Dysfunction in the initiation and maintenance of sleep, as indicated by the Sleep Disturbance Scale for Children, correlated with night-time aMT6s excretion (r = -.28, P < .05). Dysfunction in sleep breathing was inversely correlated with aMT6s (r = -.31, P < .05) and positively associated with TNF level (r = .42, P < .01). Overall such data indicate immune-pineal axis activation, with elevated TNF but not IL-6 levels associated with disrupted pineal melatonin release and sleep dysfunction in ASD. It is proposed that circadian dysregulation in ASD is intimately linked to heightened immune-inflammatory activity. Such two-way interactions of the immune-pineal axis may underpin many aspects of ASD pathophysiology, including sleep disturbances, as well as cognitive and behavioral alterations.

Optimising sleep and performance during night float: A systematic review of evidence and implications for graduate medical education trainees.

Graduate medical education (GME) training commonly requires residents and fellows to engage in night float shift work. This review aims to assess the effectiveness of interventions for trainees when preparing for, completing, and recovering from working night float shifts. We reviewed all available studies published prior to September 2019 using PubMed, Scopus, CINAHL, the Cochrane library, PsycINFO, and Google Scholar databases. We included all original, primary research articles assessing either non-pharmacological or pharmacological interventions on the chronobiological and physiological effects of night float shift work among GME trainees. Five studies (n = 179 patients) met inclusion criteria. Interventions included melatonin in the morning before sleep after night float shifts, napping during night float shifts, modafinil after a night of sleep deprivation, and caffeinated energy drinks after 6 consecutive night float shifts. Melatonin improved one measure of attention. A 2-hr nap was associated with improved speed related to task switching. Modafinil improved performance in tests of cognition. Caffeinated energy drinks led to improvement in select driving performance variables and reaction time. Effect sizes for outcome variables were calculated. Heterogeneity among the studies precluded combining the data in a meta-analysis. According to GRADE criteria, the quality of the evidence in these studies was low or very low. Our findings suggest GME trainees may benefit from utilising a limited number of interventions when preparing for or recovering from night float shift work. More investigation is needed to identify interventions that could help GME trainees adapt to and recover from working night float shifts.