Desynchronization of daily rest-activity rhythm in the days following light propofol anesthesia for colonoscopy

Anesthesia and surgery are associated with fatigue and sleep disorders, suggestive of disturbance of the circadian rest-activity rhythm. Previous studies on circadian rhythm disturbance were focused on patients undergoing general anesthesia associated with surgery. This does not permit one to draw valid conclusions about the effects of general anesthesia per se on circadian rhythms. Our study was set up to determine the impact of a hypnotic dose of propofol on the circadian rest-activity rhythm in humans under real-life conditions. Seventeen healthy subjects scheduled to receive light propofol anesthesia for ambulatory colonoscopy were investigated. Their rest-activity rhythms were assessed using actigraphic monitoring. Diurnal rest was increased, whereas nocturnal sleep was unchanged in the days following anesthesia. Nonparametric analyses showed a decrease in the strength of coupling of the rhythm to stable environmental zeitgebers and increase of fragmentation of the rhythm after anesthesia. Light general anesthesia itself impairs synchronization of the circadian rest-activity rhythm to local time in patients by acting directly on the circadian clock.     

Is shift work making your patient sick? Emerging theories and therapies for treating shift work disorder

"Shift work" is a term that applies to a wide array of nontraditional work schedules. Shift work disorder (SWD) is a circadian rhythm sleep disorder experienced by a subset of shift workers that is characterized by excessive sleepiness during work and/or insomnia during scheduled sleep times. It is estimated to affect up to 2 million Americans, and is associated with increased morbidity and mortality from metabolic risk factors, cardiovascular and gastrointestinal diseases, depression, accidents, and some kinds of cancers. Patient history is all that is needed to make a diagnosis with the International Classification of Sleep Disorders-Second Edition criteria as described herein. Circadian rhythm disorders, in which an underlying misalignment of circadian rhythm with the sleep-wake cycle occurs, may be treated by behavioral and pharmacologic approaches, including the use of hypnotics to improve the duration of sleep. However, evidence is limited with these approaches in patients diagnosed with SWD. Other treatment options may include pharmacologic interventions such as modafinil and armodafinil, which have shown efficacy in this population. Combined therapy can reduce insomnia and excessive sleepiness, and improve attention and alertness during work shifts and the subsequent commute home.     

Circadian rhythm sleep disorders

Individuals who have circadian rhythm sleep disorders present with symptoms of insomnia or excessive sleepiness and complain of an inability to sleep at their desired time. Although the primary etiology of these disorders is a misalignment between the endogenous circadian clock and the external environment, social and behavioral factors can also play important roles in perpetuating or exacerbating these disorders. Currently, the management of circadian rhythm disorders is limited to the use of bright light and melatonin to realign the circadian clock with the desired sleep time.However, as the understanding of the physiologic and genetic basis of sleep and circadian rhythm regulation advances, even more practical and effective treatments should become available.     

Is Shift work Making Your Patient Sick? Emerging Theories and Therapies for Treating Shift Work Disorder

Abstract

“Shift work” is a term that applies to a wide array of nontraditional work schedules. Shift work disorder (SWD) is a circadian rhythm sleep disorder experienced by a subset of shift workers that is characterized by excessive sleepiness during work and/or insomnia during scheduled sleep times. It is estimated to affect up to 2 million Americans, and is associated with increased morbidity and mortality from metabolic risk factors, cardiovascular and gastrointestinal diseases, depression, accidents, and some kinds of cancers. Patient history is all that is needed to make a diagnosis with the International Classification of Sleep Disorders–Second Edition criteria as described herein. Circadian rhythm disorders, in which an underlying misalignment of circadian rhythm with the sleep–wake cycle occurs, may be treated by behavioral and pharmacologic approaches, including the use of hypnotics to improve the duration of sleep. However, evidence is limited with these approaches in patients diagnosed with SWD. Other treatment options may include pharmacologic interventions such as modafinil and armodafinil, which have shown efficacy in this population. Combined therapy can reduce insomnia and excessive sleepiness, and improve attention and alertness during work shifts and the subsequent commute home.     

The relevance of sleep, circadian rhythm and lifestyle as related to a holistic theory of health.

This paper highlights the relation between health, lifestyle, sleep and circadian rhythm in disease, using a holistic theory of health, for subjects with, for example, coronary heart disease, nursed in intensive care or post-operative ward following coronary arterial by-pass surgery. The paper will also illuminate the World Health Organization's health targets nine and 13-17, adopted by the Member States of the European Region, about the relevance of lifestyle and its influence on the subject's health values for patients with coronary heart disease. Sleep is affected by a person's own will, repertoire and circumstance, both internal and external. It plays a meaningful part in maintaining good health. Disturbance of sleep leads to change in circadian rhythm and is an early symptom of psychophysiological and social ill health, independent of disease. It influences a person's values, actions and ability to adjust. Disturbance of sleep over longer periods leads to disease. Patients who have undergone, for example, coronary arterial by-pass surgery are expected to change their lifestyle. It is therefore important that the nurse can define the subject's sleep patterns and circadian rhythm.     

Excessive Daytime Sleepiness: A Clinical Review

Excessive daytime sleepiness (EDS) is a highly prevalent condition that is associated with significant morbidity. The causes of EDS are varied, and include inadequate sleep, sleep disordered breathing, circadian rhythm sleep-wake disorders, and central disorders of hypersomnolence (narcolepsy, idiopathic hypersomnia, and Kleine-Levin syndrome). Additionally, EDS could represent a symptom of an underlying medical or psychiatric disorder. Assessment of EDS includes a thorough sleep, medical, and psychiatric history, targeted clinical examination, and appropriate use of actigraphy to measure sleep duration and sleep-wake patterns, polysomnography to assess for associated conditions such as sleep-related breathing disorders or other factors that might disrupt nighttime sleep, multiple sleep latency testing to ascertain objective sleepiness and diagnose central disorders of hypersomnolence, and measurement of cerebrospinal fluid hypocretin-1 concentration. Treatment of EDS secondary to central disorders of hypersomnolence is primarily pharmacologic with wakefulness-promoting agents such as modafinil, stimulants such as methylphenidate and amphetamines, and newer agents specifically designed to improve wakefulness; behavioral interventions can provide a useful adjunct to pharmacologic treatment. When excessive sleepiness is secondary to other conditions, the treatment should focus on targeting the primary disorder. This review discusses current epidemiology, provides guidance on clinical assessments and testing, and discusses the latest treatment options. For this review, we collated the latest evidence using the search terms excessive sleepiness, hypersomnia, hypersomnolence, treatment from PubMed and MEDLINE and the latest practice parameters from the American Academy of Sleep Medicine.     

Shifted sleep hours

This paper reviews the effects of suboptimal timing of the sleep/wake cycle on sleep, alertness and well-being. It is seen that shift work and rapid travel across time zones causes disturbed sleep and increased fatigue. These effects are mainly due to sleep being displaced to a rising phase of the circadian rhythm at which the interference with sleep is at its maximum. The process may also be reversed such that pathological changes of the circadian rhythm may require sleep patterns incompatible with those of the rest of society. The review concludes with a discussion of possible counter measures.     

Strategies for coping with shift work

Shift work is a requirement of nursing and essential to provide patients with optimum levels of continuous care. However, working shift patterns can have deleterious effects on the health of nursing staff and patient safety. Adverse effects can be physical and/or psychological. This article focuses on some of the consequences of a disrupted circadian rhythm, provides advice on coping with shift work, in particular night-time shifts, and offers some practical recommendations for practice.     

Diagnosis and treatment in circadian rhythm sleep disorders

Circadian rhythm sleep disorders (CRSD) are characterized by misalignment between major sleep episode and desired sleep phase, or symptoms associated with internal desynchronization between endogenous circadian rhythm and overt sleep-wake rhythm. Endogenous circadian rhythm is mainly regulated by master circadian clock located in the suprachiasmatic nucleus. Light entrains the circadian clock according to a phase-response curve. Furthermore, social time cue affects human sleep-wake rhythm. Instructions concerning sleep hygiene including light environment play fundamental role for the treatment in CRSD. In addition, light therapy and oral melatonin administration have application to delayed sleep phase type. Diagnostic classification and treatment in each types of CRSD are reviewed in this article.     

Sleep disorders in the elderly

Geriatric patients often complain about sleep disorders, but many of the typical sleep disturbances in the elderly are thought to be normal consequences of old age and go underdiagnosed and undertreated. Sleep disorders are estimated to affect nearly 50% of older persons. Most frequently the elderly suffer from Sleep Disordered Breathing (SDB), Periodic Limb Movements in Sleep (PLMS), Restless Legs Syndrome (RLS), morning headaches, circadian rhythm disorders, excessive daytime sleepiness, Obstructive Sleep Apnea Syndrome (OSAS), and insomnia. This review describes all these common sleep problems in the older population and their possible treatment.     

Activity monitoring in sleep research, medicine and psychopharmacology

Motor activity as a diagnostic parameter has become an important feature in many fields of medicine and psychology. The concept of mobility and immobility implies the assumption that mental and behaviour disorders involve abnormal activity that can be measured to characterise the disorder itself, to diagnose its presence and to document the impact of treatment. In sleep research, activity monitoring by wrist actigraphs has proven its usefulness as an efficient method to assess the rest-activity cycle over long time periods and to estimate sleep-related features such as sleep efficiency and total sleep time. But like many other techniques and devices, activity monitoring has some limitations and drawbacks. This paper describes the basic features of wrist actigraphy in measuring nocturnal and daytime motor activity.     

Delayed circadian rhythms and substance abuse: dopamine transmission’s time has come

Disrupted sleep and circadian rhythms are linked with substance abuse risk. Human studies that investigate relationships between sleep, circadian rhythm, and substance use reward generally rely on indirect means to infer dopaminergic function, such as functional magnetic resonance imaging. In this issue of the JCI, Zhang and colleagues used positron emission tomography (PET) to image striatal dopamine D1 (D1R) and D2/3 receptor (D/3R) availability in healthy adults. The authors assessed rest-activity rhythms, then conducted PET scans using radioligand antagonists selective for D1 receptors or D2/D3 receptors to measure D1R and D2/3R availability. They also measured the subjective drug effects of oral methylphenidate. Higher D1R availability in caudate and a greater methylphenidate reward sensitivity were associated with delayed rest-activity rhythms. Unexpectedly, lower overall activity was associated with higher D2/3R availability in the nucleus accumbens, which coincided with greater methylphenidate reward score. These findings may inform personalized prevention and/or treatment interventions.     

Melatonin as a regulator of human sleep and circadian systems

Melatonin(N-acetyl-5-methoxytryptamine) is synthesized from tryptophan and is intensively secreted into the blood only in darkness (nighttime) by the pineal gland. Melatonin is not only the most reliable marker of internal circadian phase but also a potent sleep-promoting and circadian phase regulatory agent in humans. There is evidence that daytime administered melatonin is able to exhibit short-acting hypnagogic effect and phase-shifting of the circadian rhythms such that sleep timing and associated various physiological functions realign at a new desired phase. Under favor of these properties, melatonin and melatonin receptor agonists have been shown to be potent therapeutic agents for the treatment of circadian rhythm sleep disorders and some type of insomnia.     

Biological rhythms and sleep

Sleep is regulated by dual oscillatory processes, one is the hierarchical multi oscillatory circadian system and the other is the ultradian rest-activity cycle. The circadian system is composed of the central clock located in the suprachiasmatic nucleus and the peripheral clocks in a variety of tissues which express overt rhythms. The peripheral clock(s) for sleep and wakefulness in nocturnal rodents are strongly regulated by the central clock. By contract, the peripheral clock(s) in humans is more independent of and easily desynchronized from the central clock. Nocturnal sleep is characterized by REM and nonREM cycles which appear alternatively at 1.5 to 2 hour intervals. The origin of ultradian rhythm is not known. We propose an integrated model for the regulation of sleep and wakefulness by two different oscillatory systems.     

Sleep and circadian schedule disorders

The timing and synchronization of human circadian rhythms is important for health and well-being. Some individuals, for reasons that remain unclear, display less resilience or flexibility in their ability to synchronize to the 24-hour world and are thus diagnosed with a circadian schedule disorder. The objective of this article is to briefly introduce concepts about human circadian timing and to review what is known about chronic, long-term circadian schedule disorders such as delayed sleep phase syndrome, advanced sleep phase syndrome, irregular sleep-wake patterns, and non-24-hour sleep-wake disorder. Practical considerations for the clinician caring for these individuals are discussed.     

Do Circadian Preferences Influence the Sleep Patterns of Night Shift Drivers?

Objective

The objective of this study was to analyze the effect of individual circadian preferences of drivers with fixed night work schedules on sleep patterns.

Subjects and Methods

A total of 123 professional drivers, 32 indifferent preference drivers and 91 morning preference drivers of an intermunicipality and interstate bus transportation company were evaluated. All drivers underwent polysomnographic recordings after their shifts. Furthermore, they filled out a questionnaire that contained sociodemographic and health questions. The Horne and Östberg questionnaire was used to assess the subjects'' morningness-eveningness preference.

Results

The mean age was 42.54 ± 6.98 years and 82 (66.66%) of the drivers had worked for ≥15 years. A significant effect on rapid eye movement (REM) was observed in the morning preference drivers. They showed an increased sleep latency and an REM sleep percentage of 5% of the total REM time. This reveals a significant effect on sleep architecture associated with work time.

Conclusion

The drivers reported that morning preference had a significant effect on their sleep pattern indicating less REM sleep and longer REM sleep latency in the morning preference group. Thus, it is important to evaluate interactions between individual aspects of health and other parameters, such as sleep quality and work organizational factors, to promote night shift workers'' health and well-being.Key Words: Circadian rhythm, Shift work, Sleep     

Melatonin: therapeutic and clinical utilization

Melatonin, acting through melatonin receptors, is involved in numerous physiological processes including circadian entrainment, blood pressure regulation, oncogenesis, retinal physiology, seasonal reproduction, ovarian physiology, immune function and most recently in inducing osteoblast differentiation. Moreover, melatonin was proved to be a potent-free radical scavenger and a broad-spectrum antioxidant. More research is required into the effects of therapeutically modulating the melatoninergic system on circadian haemodynamics and rhythm under varying physiopathological conditions and the possible impact on morbidity and mortality in humans.     

Racial Differences in the Human Endogenous Circadian Period

The length of the endogenous period of the human circadian clock (tau) is slightly greater than 24 hours. There are individual differences in tau, which influence the phase angle of entrainment to the light/dark (LD) cycle, and in doing so contribute to morningness-eveningness. We have recently reported that tau measured in subjects living on an ultradian LD cycle averaged 24.2 hours, and is similar to tau measured using different experimental methods. Here we report racial differences in tau. Subjects lived on an ultradian LD cycle (1.5 hours sleep, 2.5 hours wake) for 3 days. Circadian phase assessments were conducted before and after the ultradian days to determine the change in circadian phase, which was attributed to tau. African American subjects had a significantly shorter tau than subjects of other races. We also tested for racial differences in our previous circadian phase advancing and phase delaying studies. In the phase advancing study, subjects underwent 4 days of a gradually advancing sleep schedule combined with a bright light pulse upon awakening each morning. In the phase delaying study, subjects underwent 4 days of a gradually delaying sleep schedule combined with evening light pulses before bedtime. African American subjects had larger phase advances and smaller phase delays, relative to Caucasian subjects. The racial differences in tau and circadian phase shifting have important implications for understanding normal phase differences between individuals, for developing solutions to the problems of jet lag and shift work, and for the diagnosis and treatment of circadian rhythm based sleep disorders such as advanced and delayed sleep phase disorder.     

Shift work

Emergency medicine, by its nature, requires shift work. Shift work has a long history and has generated many studies and regulations. It affects physiologic rhythms, sleep patterns, health, social interaction, family life, and job performance. People of certain personality types or those having certain circadian patterns may be more suited to shift work than others. The shift worker's well-being may increase if he understands how his schedule affects him; if consumer services are made available to him at all times; and if his work is scheduled carefully.     

卒中后睡眠障碍

睡眠障碍是卒中患者的常见并发症,包括日间嗜睡、失眠、异态睡眠、发作性睡病、昼夜节律紊乱、睡眠相关运动障碍及睡眠呼吸障碍。卒中后睡眠障碍的发生与多种因素有关,包括神经生物学因素及社会心理学因素。本文就卒中后睡眠结构变化、睡眠障碍的表现形式、流行病学及其病理生理机制做一综述。