Circadian rhythm sleep disorders: part II, advanced sleep phase disorder, delayed sleep phase disorder, free-running disorder, and irregular sleep-wake rhythm. An American Academy of Sleep Medicine review

Sleep education improves the sleep duration of adolescents: a randomized controlled pilot study

PURPOSE

To determine the feasibility and pilot a sleep education program in New Zealand high school students.

METHODS

A parallel, two-arm randomized controlled pilot trial was conducted. High school students (13 to 16 years) were randomly allocated to either a classroom-based sleep education program intervention (n = 15) or to a usual curriculum control group (n = 14). The sleep education program involved four 50-minute classroom-based education sessions with interactive groups. Students completed a 7-day sleep diary, a sleep questionnaire (including sleep hygiene, knowledge and problems) at baseline, post-intervention (4 weeks) and 10 weeks follow-up.

RESULTS

An overall treatment effect was observed for weekend sleep duration (F 1,24 = 5.21, p = 0.03). Participants in the intervention group slept longer during weekend nights at 5 weeks (1:37 h:min, p = 0.01) and 10 weeks: (1:32 h:min, p = 0.03) compared to those in the control group. No differences were found between groups for sleep duration on weekday nights. No significant differences were observed between groups for any of the secondary outcomes (sleep hygiene, sleep problems, or sleep knowledge).

CONCLUSIONS

A sleep education program appears to increase weekend sleep duration in the short term. Although this program was feasible, most schools are under time and resource pressure, thus alternative methods of delivery should be assessed for feasibility and efficacy. Larger trials of longer duration are needed to confirm these findings and determine the sustained effect of sleep education on sleep behavior and its impact on health and psychosocial outcomes.

COMMENTARY

A commentary on this article appears in this issue on page 793.

Metabolic consequences of sleep and circadian disorders

Sleep and circadian rhythms modulate or control daily physiological patterns with importance for normal metabolic health. Sleep deficiencies associated with insufficient sleep schedules, insomnia with short-sleep duration, sleep apnea, narcolepsy, circadian misalignment, shift work, night eating syndrome, and sleep-related eating disorder may all contribute to metabolic dysregulation. Sleep deficiencies and circadian disruption associated with metabolic dysregulation may contribute to weight gain, obesity, and type 2 diabetes potentially by altering timing and amount of food intake, disrupting energy balance, inflammation, impairing glucose tolerance, and insulin sensitivity. Given the rapidly increasing prevalence of metabolic diseases, it is important to recognize the role of sleep and circadian disruption in the development, progression, and morbidity of metabolic disease. Some findings indicate sleep treatments and countermeasures improve metabolic health, but future clinical research investigating prevention and treatment of chronic metabolic disorders through treatment of sleep and circadian disruption is needed.

Epidemiology of bedtime, arising time, and time in bed: analysis of age, gender, and ethnicity

This study investigated the epidemiology of bedtime (BT), arising time (AT), and time in bed (TIB) as a function of age, gender, and ethnicity. Sleep diary data were analyzed for 746 randomly selected community participants. This sample was comprised of 364 men (48.8%) and 382 women (51.2%), 532 Caucasians (71.3%) and 214 African Americans (28.7%), and participant ages ranged from 20 to 98 years. Regression analyses showed a main effect of age on subjective BT, AT, and TIB. The addition of gender and ethnicity to the regression model added significant variance for TIB, but not BT or AT. In general, BT declined across the lifespan, but AT showed a quadratic pattern that peaked in young adulthood, was stable in the middle years, and peaked again in the later years. This age-related combination of BT and AT resulted in greater TIB for older adults than other age groups. Women spent significantly greater TIB than men, and African Americans spent significantly more TIB than Caucasians. These results suggest that there are distinct behavioral sleep patterns associated with age and, in the case of TIB, gender and ethnicity. These patterns may have significant clinical implications, particularly with respect to age.

Sleep duration and incidence of lung cancer in ageing men

BACKGROUND

Previous studies have suggested an association between sleep duration and cancer. However, the information on sleep duration regard to risk of lung cancer is scanty.

METHODS

Analysed data comprised prospective population-based cohort of 2586 men (aged 42-60 years) from Eastern Finland. Baseline survey and clinical examinations took place 1984-1989, and diagnosed lung cancers were obtained until the end of 2011 through linkage with the Finnish Cancer Registry. Self-reported sleep was categorized as ≤6.5 h, 7-7.5 h, and ≥8 h. Subjects with prior history of cancer or psychotropic medication (hypnotics or sedatives) were excluded from the analyses. Cox proportional hazards models with adjustments for possible confounders were used to examine the association.

RESULTS

Significant association between sleep duration and increased lung cancer risk was observed after adjustments for age, examination years, cumulative smoking history, family cancer history and Human Population Laboratory Depression scale scores (HR 2.12, 95% CI 1.17-3.85 for ≤6.5 h sleep, and HR 1.88, 95% CI 1.09-3.22 for ≥8 h sleep). Associations were even stronger among current smokers (HR 2.23, 95% CI 1.14-4.34 for ≤6.5 h sleep, and HR 2.09, 95% CI 1.14-3.81 for ≥8 h sleep). After further adjustments for alcohol consumption, physical activity, body mass index, marital status, education years, night work, employment status, asthma and chronic bronchitis, the association remained significant both in the whole study population and among smokers. When cumulative smoking history was replaced by current smoking in the adjustments, the increased risk was limited to those who slept<6.5 h.

CONCLUSIONS

Sleep duration of less than 7-7.5 hours or more than 7-7.5 hours associates with increased lung cancer risk. The physiological factors underlying the association are complex, and they may relate to melatonin excretion patterns, low-grade inflammation in cancer development process or disruptions in circadian rhythmicity.

Clinical Implications of Impaired Sleep

Despite its pervasiveness in primary care, deficient sleep often is underappreciated as a cue to other health risks. Accordingly, this review discusses contemporary evidence-based perspectives on impaired sleep and its associations with other lifestyle medicine concerns, including obesity, cardiovascular conditions, psychological problems, and health-compromising habits. The potential clinical benefits of promoting sleep health also will be considered.

Sleep health: can we define it? Does it matter?

Good sleep is essential to good health. Yet for most of its history, sleep medicine has focused on the definition, identification, and treatment of sleep problems. Sleep health is a term that is infrequently used and even less frequently defined. It is time for us to change this. Indeed, pressures in the research, clinical, and regulatory environments require that we do so. The health of populations is increasingly defined by positive attributes such as wellness, performance, and adaptation, and not merely by the absence of disease. Sleep health can be defined in such terms. Empirical data demonstrate several dimensions of sleep that are related to health outcomes, and that can be measured with self-report and objective methods. One suggested definition of sleep health and a description of self-report items for measuring it are provided as examples. The concept of sleep health synergizes with other health care agendas, such as empowering individuals and communities, improving population health, and reducing health care costs. Promoting sleep health also offers the field of sleep medicine new research and clinical opportunities. In this sense, defining sleep health is vital not only to the health of populations and individuals, but also to the health of sleep medicine itself.

A review of signals used in sleep analysis

This article presents a review of signals used for measuring physiology and activity during sleep and techniques for extracting information from these signals. We examine both clinical needs and biomedical signal processing approaches across a range of sensor types. Issues with recording and analysing the signals are discussed, together with their applicability to various clinical disorders. Both univariate and data fusion (exploiting the diverse characteristics of the primary recorded signals) approaches are discussed, together with a comparison of automated methods for analysing sleep.

Why the dim light melatonin onset (DLMO) should be measured before treatment of patients with circadian rhythm sleep disorders

Treatment of circadian rhythm sleep disorders (CRSD) may include light therapy, chronotherapy and melatonin. Exogenous melatonin is increasingly being used in patients with insomnia or CRSD. Although pharmacopoeias and the European food safety authority (EFSA) recommend administering melatonin 1-2 h before desired bedtime, several studies have shown that melatonin is not always effective if administered according to that recommendation. Crucial for optimal treatment of CRSD, melatonin and other treatments should be administered at a time related to individual circadian timing (typically assessed using the dim light melatonin onset (DLMO)). If not administered according to the individual patient's circadian timing, melatonin and other treatments may not only be ineffective, they may even result in contrary effects. Endogenous melatonin levels can be measured reliably in saliva collected at the patient's home. A clinically reliably DLMO can be calculated using a fixed threshold. Diary and polysomnographic sleep-onset time do not reliably predict DLMO or circadian timing in patients with CRSD. Knowing the patient's individual circadian timing by assessing DLMO can improve diagnosis and treatment of CRSD with melatonin as well as other therapies such as light or chronotherapy, and optimizing treatment timing will shorten the time required to achieve results.

From molecules to behavior and the clinic: Integration in chronobiology

Chronobiology, especially the study of circadian rhythms, provides a model scientific field in which philosophers can study how investigators from a variety of disciplines working at different levels of organization are each contributing to a multi-level account of the responsible mechanism. I focus on how the framework of mechanistic explanation integrates research designed to decompose the mechanism with efforts directed at recomposition that relies especially on computation models. I also examine how recently the integration has extended beyond basic research to the processes through which the disruption of circadian rhythms contributes to disease, including various forms of cancer. Understanding these linkages has been facilitated by discoveries about how circadian mechanisms interact with mechanisms involved in other physiological processes, including the cell cycle and the immune system.

Aging, circadian rhythms and depressive disorders: a review

INTRODUCTION

Aging is typically associated with impairing behavioral patterns that are frequently and inappropriately seen as normal. Circadian rhythm changes and depressive disorders have been increasingly proposed as the two main overlapping and interpenetrating changes that take place in older age. This study aims to review the state of the art on the subject concerning epidemiology, pathophysiological mechanism, clinical findings and relevance, as well as available treatment options.

MATERIALS AND METHODS

A nonsystematic review of all English language PubMed articles published between 1995 and December 2012 using the terms "circadian rhythms", "mood disorders", "depression", "age", "aging", "elderly" and "sleep".

DISCUSSION AND CONCLUSION

Sleep disorders, mainly insomnia, and depression have been demonstrated to be highly co-prevalent and mutually precipitating conditions in the elderly population. There is extensive research on the pathophysiological mechanisms through which age conditions circadian disruption, being the disruption of the Melatonin system one of the main changes. However, research linking clearly and unequivocally circadian disruption and mood disorders is still lacking. Nonetheless, there are consistently described molecular changes on shared genes and also several proposed pathophysiological models linking depression and sleep disruption, with clinical studies also suggesting a bi-directional relationship between these pathologies. In spite of this suggested relation, clinical evaluation of these conditions in elderly patients consistently reveals itself rather complicated due to the frequently co-existing co-morbidities, some of them having been demonstrated to alter sleep and mood patters. This is the case of strokes, forms of dementia such as Alzheimer and Parkinson, several neurodegenerative disorders, among others. Although there are to the present no specific treatment guidelines, available treatment options generally base themselves on the premise that depression and sleep disturbances share a bidirectional relationship and so, the adoption of measures that address specifically one of the conditions will reciprocally benefit the other. Treatment options range from Cognitive Behavioral Therapy, Chronotherapy, and Light therapy, to drugs such as Melatonin/Melatonin agonists, antidepressants and sedatives.

Circadian rhythms in liver physiology and liver diseases

In mammals, circadian rhythms function to coordinate a diverse panel of physiological processes with environmental conditions such as food and light. As the driving force for circadian rhythmicity, the molecular clock is a self-sustained transcription-translational feedback loop system consisting of transcription factors, epigenetic modulators, kinases/phosphatases, and ubiquitin E3 ligases. The molecular clock exists not only in the suprachiasmatic nuclei of the hypothalamus but also in the peripheral tissues to regulate cellular and physiological function in a tissue-specific manner. The circadian clock system in the liver plays important roles in regulating metabolism and energy homeostasis. Clock gene mutant animals display impaired glucose and lipid metabolism and are susceptible to diet-induced obesity and metabolic dysfunction, providing strong evidence for the connection between the circadian clock and metabolic homeostasis. Circadian-controlled hepatic metabolism is partially achieved by controlling the expression and/or activity of key metabolic enzymes, transcription factors, signaling molecules, and transporters. Reciprocally, intracellular metabolites modulate the molecular clock activity in response to the energy status. Although still at the early stage, circadian clock dysfunction has been implicated in common chronic liver diseases. Circadian dysregulation of lipid metabolism, detoxification, reactive oxygen species (ROS) production, and cell-cycle control might contribute to the onset and progression of liver steatosis, fibrosis, and even carcinogenesis. In summary, these findings call for a comprehensive study of the function and mechanisms of hepatic circadian clock to gain better understanding of liver physiology and diseases.

Extraocular light via the ear canal does not acutely affect human circadian physiology, alertness and psychomotor vigilance performance

We aimed at testing potential effects of extraocular bright light via the ear canals on human evening melatonin levels, sleepiness and psychomotor vigilance performance. Twenty healthy young men and women (10/10) kept a regular sleep-wake cycle during the 2-week study. The volunteers reported to the laboratory on three evenings, 2 h 15 min before usual bedtime, on average at 21:45 h. They were exposed to three different light conditions, each lasting for 12 min: extraocular bright light via the ear canal, ocular bright light as an active control condition and a control condition (extraocular light therapy device with completely blacked out LEDs). The timing of exposure was on average from 22:48 to 23:00 h. During the 2-h protocol, saliva samples were collected in 15-min intervals for melatonin assays along with subjective sleepiness ratings, and the volunteers performed a 10-min visual psychomotor vigilance task (PVT) prior to and after each light condition. The evening melatonin rise was significantly attenuated after the 12-min ocular bright light exposure while no significant changes were observed after the extraocular bright light and sham light condition. Subjective sleepiness decreased immediately over a short period only after ocular light exposure. No significant differences were observed for mean reaction times and the number of lapses for the PVT between the three light conditions. We conclude that extraocular transcranial light exposure in the late evening does not suppress melatonin, reduce subjective sleepiness or improve performance, and therefore, does not acutely influence the human circadian timing system.

Combination of light and melatonin time cues for phase advancing the human circadian clock

STUDY OBJECTIVES

Photic and non-photic stimuli have been shown to shift the phase of the human circadian clock. We examined how photic and non-photic time cues may be combined by the human circadian system by assessing the phase advancing effects of one evening dose of exogenous melatonin, alone and in combination with one session of morning bright light exposure.

DESIGN

Randomized placebo-controlled double-blind circadian protocol. The effects of four conditions, dim light (∼1.9 lux, ∼0.6 Watts/m(2))-placebo, dim light-melatonin (5 mg), bright light (∼3000 lux, ∼7 Watts/m(2))-placebo, and bright light-melatonin on circadian phase was assessed by the change in the salivary dim light melatonin onset (DLMO) prior to and following treatment under constant routine conditions. Melatonin or placebo was administered 5.75 h prior to habitual bedtime and 3 h of bright light exposure started 1 h prior to habitual wake time.

SETTING

Sleep and chronobiology laboratory environment free of time cues.

PARTICIPANTS

Thirty-six healthy participants (18 females) aged 22 ± 4 y (mean ± SD).

RESULTS

Morning bright light combined with early evening exogenous melatonin induced a greater phase advance of the DLMO than either treatment alone. Bright light alone and melatonin alone induced similar phase advances.

CONCLUSION

Information from light and melatonin appear to be combined by the human circadian clock. The ability to combine circadian time cues has important implications for understanding fundamental physiological principles of the human circadian timing system. Knowledge of such principles is important for designing effective countermeasures for phase-shifting the human circadian clock to adapt to jet lag, shift work, and for designing effective treatments for circadian sleep-wakefulness disorders.

Circadian Rhythm Sleep Disorders

OBJECTIVE

To review circadian rhythm sleep disorders, including underlying causes, diagnostic considerations, and typical treatments.

METHODS

Literature review and discussion of specific cases.

RESULTS

Survey studies ^1,2 suggest that up to 3% of the adult population suffers from a circadian rhythm sleep disorder (CRSD). However, these sleep disorders are often confused with insomnia, and an estimated 10% of adult and 16% of adolescent sleep disorders patients may have a CRSD ^3-6. While some CRSD (such as jet lag) can be self-limiting, others when untreated can lead to adverse medical, psychological, and social consequences. The International Classification of Sleep Disorders classifies CRSD as dyssomnias, with six subtypes: Advanced Sleep Phase Type, Delayed Sleep Phase Type, Irregular Sleep Wake Type, Free Running Type, Jet Lag Type, and Shift Work Type. The primary clinical characteristic of all CRSD is an inability to fall asleep and wake at the desired time. It is believed that CRSD arise from a problem with the internal biological clock (circadian timing system) and/or misalignment between the circadian timing system and the external 24-hour environment. This misalignment can be the result of biological and/or behavioral factors. CRSD can be confused with other sleep or medical disorders.

CONCLUSIONS

Circadian rhythm sleep disorders are a distinct class of sleep disorders characterized by a mismatch between the desired timing of sleep and the ability to fall asleep and remain asleep. If untreated, CRSD can lead to insomnia and excessive daytime sleepiness, with negative medical, psychological, and social consequences. It is important for physicians to recognize potential circadian rhythm sleep disorders so that appropriate diagnosis, treatment, and referral can be made.

Self-reported sleep disturbances in renal transplant recipients

BACKGROUND

Poor sleep quality (SQ) and daytime sleepiness (DS) are common in renal transplant (RTx) recipients; however, related data are rare. This study describes the prevalence and frequency of self-reported sleep disturbances in RTx recipients.

METHODS

This cross-sectional study included 249 RTx recipients transplanted at three Swiss transplant centers. All had reported poor SQ and / or DS in a previous study. With the Survey of Sleep (SOS) self-report questionnaire, we screened for sleep and health habits, sleep history, main sleep problems and sleep-related disturbances. To determine a basis for preliminary sleep diagnoses according to the International Classification of Sleep Disorders (ICSD), 164 subjects were interviewed (48 in person, 116 via telephone and 85 refused). Descriptive statistics were used to analyze the data and to determine the frequencies and prevalences of specific sleep disorders.

RESULTS

The sample had a mean age of 59.1 ± 11.6 years (60.2% male); mean time since Tx was 11.1 ± 7.0 years. The most frequent sleep problem was difficulty staying asleep (49.4%), followed by problems falling asleep (32.1%). The most prevalent sleep disturbance was the need to urinate (62.9%), and 27% reported reduced daytime functionality. Interview data showed that most suffered from the first ICSD category: insomnias.

CONCLUSION

Though often disregarded in RTx recipients, sleep is an essential factor of wellbeing. Our findings show high prevalences and incidences of insomnias, with negative impacts on daytime functionality. This indicates a need for further research on the clinical consequences of sleep disturbances and the benefits of insomnia treatment in RTx recipients.

A molecular and chemical perspective in defining melatonin receptor subtype selectivity

Melatonin is primarily synthesized and secreted by the pineal gland during darkness in a normal diurnal cycle. In addition to its intrinsic antioxidant property, the neurohormone has renowned regulatory roles in the control of circadian rhythm and exerts its physiological actions primarily by interacting with the G protein-coupled MT₁ and MT₂ transmembrane receptors. The two melatonin receptor subtypes display identical ligand binding characteristics and mediate a myriad of signaling pathways, including adenylyl cyclase inhibition, phospholipase C stimulation and the regulation of other effector molecules. Both MT₁ and MT₂ receptors are widely expressed in the central nervous system as well as many peripheral tissues, but each receptor subtype can be linked to specific functional responses at the target tissue. Given the broad therapeutic implications of melatonin receptors in chronobiology, immunomodulation, endocrine regulation, reproductive functions and cancer development, drug discovery and development programs have been directed at identifying chemical molecules that bind to the two melatonin receptor subtypes. However, all of the melatoninergics in the market act on both subtypes of melatonin receptors without significant selectivity. To facilitate the design and development of novel therapeutic agents, it is necessary to understand the intrinsic differences between MT₁ and MT₂ that determine ligand binding, functional efficacy, and signaling specificity. This review summarizes our current knowledge in differentiating MT₁ and MT₂ receptors and their signaling capacities. The use of homology modeling in the mapping of the ligand-binding pocket will be described. Identification of conserved and distinct residues will be tremendously useful in the design of highly selective ligands.

Solving the mystery of human sleep schedules one mutation at a time

Sleep behavior remains one of the most enigmatic areas of life. The unanswered questions range from "why do we sleep?" to "how we can improve sleep in today's society?" Identification of mutations responsible for altered circadian regulation of human sleep lead to unique opportunities for probing these territories. In this review, we summarize causative circadian mutations found from familial genetic studies to date. We also describe how these mutations mechanistically affect circadian function and lead to altered sleep behaviors, including shifted or shortening of sleep patterns. In addition, we discuss how the investigation of mutations can not only expand our understanding of the molecular mechanisms regulating the circadian clock and sleep duration, but also bridge the pathways between clock/sleep and other human physiological conditions and ailments such as metabolic regulation and migraine headaches.

Characteristic effects of stochastic oscillatory forcing on neural firing: analytical theory and comparison to paddlefish electroreceptor data

Stochastic signals with pronounced oscillatory components are frequently encountered in neural systems. Input currents to a neuron in the form of stochastic oscillations could be of exogenous origin, e.g. sensory input or synaptic input from a network rhythm. They shape spike firing statistics in a characteristic way, which we explore theoretically in this report. We consider a perfect integrate-and-fire neuron that is stimulated by a constant base current (to drive regular spontaneous firing), along with Gaussian narrow-band noise (a simple example of stochastic oscillations), and a broadband noise. We derive expressions for the nth-order interval distribution, its variance, and the serial correlation coefficients of the interspike intervals (ISIs) and confirm these analytical results by computer simulations. The theory is then applied to experimental data from electroreceptors of paddlefish, which have two distinct types of internal noisy oscillators, one forcing the other. The theory provides an analytical description of their afferent spiking statistics during spontaneous firing, and replicates a pronounced dependence of ISI serial correlation coefficients on the relative frequency of the driving oscillations, and furthermore allows extraction of certain parameters of the intrinsic oscillators embedded in these electroreceptors.

Entrainment of the human circadian clock to the natural light-dark cycle

The electric light is one of the most important human inventions. Sleep and other daily rhythms in physiology and behavior, however, evolved in the natural light-dark cycle [1], and electrical lighting is thought to have disrupted these rhythms. Yet how much the age of electrical lighting has altered the human circadian clock is unknown. Here we show that electrical lighting and the constructed environment is associated with reduced exposure to sunlight during the day, increased light exposure after sunset, and a delayed timing of the circadian clock as compared to a summer natural 14 hr 40 min:9 hr 20 min light-dark cycle camping. Furthermore, we find that after exposure to only natural light, the internal circadian clock synchronizes to solar time such that the beginning of the internal biological night occurs at sunset and the end of the internal biological night occurs before wake time just after sunrise. In addition, we find that later chronotypes show larger circadian advances when exposed to only natural light, making the timing of their internal clocks in relation to the light-dark cycle more similar to earlier chronotypes. These findings have important implications for understanding how modern light exposure patterns contribute to late sleep schedules and may disrupt sleep and circadian clocks.

Non-24-Hour Disorder in Blind Individuals Revisited: Variability and the Influence of Environmental Time Cues

STUDY OBJECTIVES

To assess the interindividual and intraindividual variability in the circadian rhythms of blind individuals with non-24-h disorder and to quantify the influence of environmental time cues in blind subjects lacking entrainment (non-24-h individuals or N-24s).

DESIGN

An observational study of 21 N-24s (11 females and 10 males, age 9-78 years) who kept a sleep/wake schedule of their choosing. Circadian phase was determined using the melatonin onset (MO) from plasma or saliva samples that were collected every 2 weeks. Melatonin concentrations were measured by radioimmunoassay. A total of 469 MO assessments were conducted over 5,536 days of study. The rate of drift of circadian phase was calculated using a series of MOs (total number of hours the MO drifted divided by the total number of days studied). Stability of the rest/activity rhythm was calculated using chi-squared periodogram analysis of wrist actigraphy data in 19 subjects.

SETTING

Academic medical center.

PARTICIPANTS

Paid volunteers.

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

Subjects lacked entrainment such that circadian phase drifted an average (± standard deviation) of 0.39 ± 0.29 h later per day; however, there was notable intersubject and intrasubject variability in the rate of drift including relative coordination and periods of transient entrainment during which there was little to no drift in the circadian phase. A regular, reproducible, and significant oscillation in the rate of drift was detected in 14 of the 21 subjects. A significant non-24-h rest/activity rhythm was detected in 18 of 19 subjects. There was a strong correlation (r = 0.793, P = 0.0001) between the non-24-h rest/activity rhythm and the rate of drift of the circadian phase.

CONCLUSIONS

Most N-24s are influenced by unidentified environmental time cues and the non-entrained biological clock in such N-24s is reflected in their rest/activity rhythms. These findings may have diagnostic and treatment implications: this disorder might be diagnosed with actigraphy alone, relative coordination and transient entrainment may result in misdiagnosis and responsiveness to environmental time cues may influence treatment success with oral melatonin.

CITATION

Emens JS; Laurie AL; Songer JB; Lewy AJ. Non-24-hour disorder in blind individuals revisited: variability and the influence of environmental time cues. SLEEP 2013;36(7):1091-1100.

Sleep loss and the inflammatory response in mice under chronic environmental circadian disruption

Shift work and trans-time zone travel lead to insufficient sleep and numerous pathologies. Here, we examined sleep/wake dynamics during chronic exposure to environmental circadian disruption (ECD), and if chronic partial sleep loss associated with ECD influences the induction of shift-related inflammatory disorder. Sleep and wakefulness were telemetrically recorded across three months of ECD, in which the dark-phase of a light-dark cycle was advanced weekly by 6 h. A three month regimen of ECD caused a temporary reorganization of sleep (NREM and REM) and wake processes across each week, resulting in an approximately 10% net loss of sleep each week relative to baseline levels. A separate group of mice were subjected to ECD or a regimen of imposed wakefulness (IW) aimed to mimic sleep amounts under ECD for one month. Fos-immunoreactivity (IR) was quantified in sleep-wake regulatory areas: the nucleus accumbens (NAc), basal forebrain (BF), and medial preoptic area (MnPO). To assess the inflammatory response, trunk blood was treated with lipopolysaccharide (LPS) and subsequent release of IL-6 was measured. Fos-IR was greatest in the NAc, BF, and MnPO of mice subjected to IW. The inflammatory response to LPS was elevated in mice subjected to ECD, but not mice subjected to IW. Thus, the net sleep loss that occurs under ECD is not associated with a pathological immune response.

Dementia and sleep

Sleep evaluation can be essential in the treatment of dementia because sleep-related issues are common in dementia, often treatable, affect patient function, and are a major cause of caregiver distress. This article provides a practical approach to treatment of sleep in patients with dementia. Certain specific sleep disorders can be associated with certain underlying disorders and greater knowledge of these relationships is leading to more refined treatment approaches. Whether a sleep-related disorder such as obstructive sleep apnea, or limited sleep time, predisposes to the development of dementia is an active area of research.

Sleep medicine pharmacotherapeutics overview: today, tomorrow, and the future (Part 1: insomnia and circadian rhythm disorders)

Over the past 10 years, significant strides have been made in the understanding, development, and availability of sleep disorder therapeutics. In this review series, we discuss the current evidence surrounding the mechanisms of actions, indications, efficacy, and adverse side effects associated with the available armamentarium of sleep over-the-counter and pharmacotherapeutics. This article is the first of a two-part series that covers the therapeutics for insomnia and circadian rhythm disorders.

Biological and psychological rhythms: an integrative approach to rhythm disturbances in autistic disorder

Biological rhythms are crucial phenomena that are perfect examples of the adaptation of organisms to their environment. A considerable amount of work has described different types of biological rhythms (from circadian to ultradian), individual differences in their patterns and the complexity of their regulation. In particular, the regulation and maturation of the sleep-wake cycle have been thoroughly studied. Its desynchronization, both endogenous and exogenous, is now well understood, as are its consequences for cognitive impairments and health problems. From a completely different perspective, psychoanalysts have shown a growing interest in the rhythms of psychic life. This interest extends beyond the original focus of psychoanalysis on dreams and the sleep-wake cycle, incorporating central theoretical and practical psychoanalytic issues related to the core functioning of the psychic life: the rhythmic structures of drive dynamics, intersubjective developmental processes and psychic containment functions. Psychopathological and biological approaches to the study of infantile autism reveal the importance of specific biological and psychological rhythmic disturbances in this disorder. Considering data and hypotheses from both perspectives, this paper proposes an integrative approach to the study of these rhythmic disturbances and offers an etiopathogenic hypothesis based on this integrative approach.

Circadian rhythm sleep disorders in patients with multiple sclerosis and its association with fatigue: A case-control study

BACKGROUND

Circadian rhythm sleep disorders are a presentation of sleep disorders in patients with multiple sclerosis (MS). This study aims to compare this problem in MS patients with healthy people and to determine its association with chronic fatigue in MS patients.

MATERIALS AND METHODS

A case-control study was performed on 120 MS patients and 60 healthy subjects matched for age and sex, in 2009 in MS Clinic Alzahra Hospital. Sleep quality, rhythm and fatigue severity were assessed using PSQI (Pittsburgh sleep quality index) and FSS (Fatigue severity Scale) questionnaires, respectively. Its reliability and validity has been confirmed in several studies (Cronbach's alpha = 0.83). This index has seven sections including patient's assessment of his/her sleep, sleep duration, efficacy of routine sleep, sleep disorders, use of hypnotic medication, and dysfunction in daily activities.

RESULTS

Circadian rhythm sleep disorder was more frequent in MS patients relative to healthy subjects (P: 0.002). It was higher in MS patients with severe fatigue relative to MS patients with mild fatigue (P: 0.05). Fatigue severity was 49.9 ± 8.2 and 22.5 ± 7.4 in the first and second group, respectively. PSQI index was 7.9 ± 4.5 in patients with severe fatigue and 5.9 ± 4.5 in patients with mild fatigue and 4.5 ± 2.4 in the control group (P: 0.0001).

CONCLUSION

Circadian rhythm sleep disorders are more frequent in MS patients and those with fatigue. Recognition and management of circadian rhythm sleep disorders in MS patients, especially those with fatigue may be helpful in improving care of these patients.

Sleep disorders as a cause of motor vehicle collisions

Studies have shown that a large proportion of traffic accidents around the world are related to inadequate or disordered sleep. Recent surveys have linked driver fatigue to 16% to 20% of serious highway accidents in the UK, Australia, and Brazil. Fatigue as a result of sleep disorders (especially obstructive sleep apnea), excessive workload and lack of physical and mental rest, have been shown to be major contributing factors in motor vehicle accidents. A number of behavioral, physiological, and psychometric tests are being used increasingly to evaluate the impact of fatigue on driver performance. These include the oculography, polysomnography, actigraphy, the maintenance of wakefulness test, and others. Various strategies have been proposed for preventing or reducing the impact of fatigue on motor vehicle accidents. These have included: Educational programs emphasizing the importance of restorative sleep and the need for drivers to recognize the presence of fatigue symptoms, and to determine when to stop to sleep; The use of exercise to increase alertness and to promote restorative sleep; The use of substances or drugs to promote sleep or alertness (i.e. caffeine, modafinil, melatonin and others), as well as specific sleep disorders treatment; The use of CPAP therapy for reducing excessive sleepiness among drivers who have been diagnosed with obstructive sleep apnea. The evidence cited in this review justifies the call for all efforts to be undertaken that may increase awareness of inadequate sleep as a cause of traffic accidents. It is strongly recommended that, for the purpose of promoting highway safety and saving lives, all disorders that cause excessive sleepiness should be investigated and monitored.

Metabolism and the circadian clock converge

Circadian rhythms occur in almost all species and control vital aspects of our physiology, from sleeping and waking to neurotransmitter secretion and cellular metabolism. Epidemiological studies from recent decades have supported a unique role for circadian rhythm in metabolism. As evidenced by individuals working night or rotating shifts, but also by rodent models of circadian arrhythmia, disruption of the circadian cycle is strongly associated with metabolic imbalance. Some genetically engineered mouse models of circadian rhythmicity are obese and show hallmark signs of the metabolic syndrome. Whether these phenotypes are due to the loss of distinct circadian clock genes within a specific tissue versus the disruption of rhythmic physiological activities (such as eating and sleeping) remains a cynosure within the fields of chronobiology and metabolism. Becoming more apparent is that from metabolites to transcription factors, the circadian clock interfaces with metabolism in numerous ways that are essential for maintaining metabolic homeostasis.

Effects of sleep loss on the rest-activity circadian rhythm of helpers participating in continuous dogsled races

OBJECTIVE

The Finnmarksløpet dogsled race lasts up to 7 days. Helpers, who keep time, coach, and transport equipment, have to be alert though they have little and fragmented sleep. This study investigated disruptions of the rest-activity rhythm among helpers.

METHODS

10 helpers were monitored by actigraph a week before, during, and after the race. Sleep logs, sleepiness rate, and self-reported quality of sleep were collected.

RESULTS

Nonparametric circadian rhythm analysis showed significant differences between the pre- and postrace interdaily stability and amplitude of rhythm. Compared to prerace, sleepiness at bedtime was increased and number of nocturnal awakenings was reduced postrace, although the actigraphic outputs showed no improvement in sleep quality. Helpers who were engaged in the race for a longer span (5-6 days) had more difficulty recovering from the sleep loss accumulated during the race than those engaged for a shorter time (2-3 days).

CONCLUSION

Poor sleep combined with prolonged and demanding mental focus for 2 days or more has a negative influence upon the rest-activity cycle, though complete restoration of the cycle occurs over 1 week or more. Being in such a condition for ≥ 5 days leads to disruptions of the circadian component of the sleep-wake cycle that hampers the sleep recovery process. Disrupted sleep and demanding mental requirements are common in long-distance sporting events as well as among shift workers. Follow-up intervention should be made in such cases to ensure the return of a healthy rest-activity rhythm and sleep quality.

Polymorphism of CLOCK gene rs 4580704 C > G is associated with susceptibility of Alzheimer's disease in a Chinese population

BACKGROUND AND AIMS

The association of polymorphism of circadian locomotor output cycle kaput (CLOCK) gene rs 4580704 C/G with susceptibility of Alzheimer's disease (AD) was examined in the present study.

METHODS

This was a case/control study and investigated the association of polymorphism of CLOCK gene rs 4580704 C/G with susceptibility of AD. Genotypes of apolipoprotein E (APOE) and CLOCK gene rs 4580704 C/G were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) detection method.

RESULTS

This study was comprised of 296 unrelated AD patients and 423 controls. We performed an analysis the association of polymorphism of CLOCK gene rs 4580704 C/G with susceptibility of AD. In the whole sample or APOEε4 noncarriers, prevalence of C carriers in CLOCK gene rs 4580704 in AD patients was significantly higher than in controls (in the whole sample: χ(2) = 13.773, p <0.0001; in APOEε4 noncarriers: χ(2) = 51.588, p <0.0001). However, among APOEε4 carriers, prevalence of C carriers in CLOCK gene rs 4580704 between patients and controls was not statistically significant (χ(2) = 0.753, p = 0.386).

CONCLUSIONS

Among APOEε4 noncarriers, C carriers in CLOCK gene rs 4580704 were associated with a high susceptibility of AD; however, among APOEε4 carriers the functional polymorphism of clock gene rs 4580704 C/G was not associated with AD susceptibility.

Circadian rhythms, sleep deprivation, and human performance

Much of the current science on, and mathematical modeling of, dynamic changes in human performance within and between days is dominated by the two-process model of sleep-wake regulation, which posits a neurobiological drive for sleep that varies homeostatically (increasing as a saturating exponential during wakefulness and decreasing in a like manner during sleep), and a circadian process that neurobiologically modulates both the homeostatic drive for sleep and waking alertness and performance. Endogenous circadian rhythms in neurobehavioral functions, including physiological alertness and cognitive performance, have been demonstrated using special laboratory protocols that reveal the interaction of the biological clock with the sleep homeostatic drive. Individual differences in circadian rhythms and genetic and other components underlying such differences also influence waking neurobehavioral functions. Both acute total sleep deprivation and chronic sleep restriction increase homeostatic sleep drive and degrade waking neurobehavioral functions as reflected in sleepiness, attention, cognitive speed, and memory. Recent evidence indicating a high degree of stability in neurobehavioral responses to sleep loss suggests that these trait-like individual differences are phenotypic and likely involve genetic components, including circadian genes. Recent experiments have revealed both sleep homeostatic and circadian effects on brain metabolism and neural activation. Investigation of the neural and genetic mechanisms underlying the dynamically complex interaction between sleep homeostasis and circadian systems is beginning. A key goal of this work is to identify biomarkers that accurately predict human performance in situations in which the circadian and sleep homeostatic systems are perturbed.

Circadian period and the timing of melatonin onset in men and women: predictors of sleep during the weekend and in the laboratory

Sleep complaints and irregular sleep patterns, such as curtailed sleep during workdays and longer and later sleep during weekends, are common. It is often implied that differences in circadian period and in entrained phase contribute to these patterns, but few data are available. We assessed parameters of the circadian rhythm of melatonin at baseline and in a forced desynchrony protocol in 35 participants (18 women) with no sleep disorders. Circadian period varied between 23 h 50 min and 24 h 31 min, and correlated positively (n = 31, rs  = 0.43, P = 0.017) with the timing of the melatonin rhythm relative to habitual bedtime. The phase of the melatonin rhythm correlated with the Insomnia Severity Index (n = 35, rs  = 0.47, P = 0.004). Self-reported time in bed during free days also correlated with the timing of the melatonin rhythm (n = 35, rs  = 0.43, P = 0.01) as well as with the circadian period (n = 31, rs  = 0.47, P = 0.007), such that individuals with a more delayed melatonin rhythm or a longer circadian period reported longer sleep during the weekend. The increase in time in bed during the free days correlated positively with circadian period (n = 31, rs  = 0.54, P = 0.002). Polysomnographically assessed latency to persistent sleep (n = 34, rs  = 0.48, P = 0.004) correlated with the timing of the melatonin rhythm when participants were sleeping at their habitual bedtimes in the laboratory. This correlation was significantly stronger in women than in men (Z = 2.38, P = 0.017). The findings show that individual differences in circadian period and phase of the melatonin rhythm associate with differences in sleep, and suggest that individuals with a long circadian period may be at risk of developing sleep problems.

DSM-IV psychiatric comorbidity according to symptoms of insomnia: a nationwide sample of Korean adults

PURPOSE

The diagnosis of insomnia is based on the presence of four different symptoms: difficulty in initiating sleep (DIS), difficulty in maintaining sleep (DMS), early morning awakening (EMA), and non-restorative sleep (NRS). This study investigated the differences in sociodemographic correlates and psychiatric comorbidity between the four symptoms of insomnia in the general population of South Korea.

METHODS

A sample of the population aged 18-64 (N = 6,510) was questioned using a face-to-face interview. Insomnia was defined as having at least one of the four following symptoms three or more times per week: DIS, DMS, EMA, and NRS. Psychiatric disorders were evaluated using the Korean version of Composite International Diagnostic Interview. Logistic regression analysis was used to test each of the sleep outcomes (DIS, DMS, EMA, or NRS) for an association with sociodemographic and clinical variables.

RESULTS

The prevalence of DIS, DMS, EMA, and NRS were 7.9 % (95 % CI 6.6-9.5 %), 7.9 % (95 % CI 6.5-9.6 %), 4.9 % (95 % CI 3.9-6.0 %), and 14.8 % (95 % CI 12.6-17.4 %), respectively. The overall prevalence of insomnia was 19.0 % (95 % CI 16.1-22.2 %). Being separated, divorced, or widowed, being single, having a part-time job, having a psychiatric illness, and having a physical illness were all significantly related to insomnia. Older age also increased the risk of DMS and EMA, and younger age was a risk factor for NRS. The presence of most psychiatric disorders was significantly related to insomnia. However, the relationship between the psychiatric illness and each insomnia symptom varied and was dependent on the insomnia symptom.

CONCLUSIONS

Most psychiatric disorders were significantly associated with each insomnia symptom in different ways. Differences in sociodemographic and clinical correlates between the four insomnia symptoms implied the heterogeneous characteristics of insomnia as defined by the current diagnostic criteria.

Classification of sleep disorders

The classification of sleep disorders is necessary to discriminate between disorders and to facilitate an understanding of symptoms, etiology, and pathophysiology that allows for appropriate treatment. The earliest classification systems, largely organized according to major symptoms (insomnia, excessive sleepiness, and abnormal events that occur during sleep), were unable to be based on pathophysiology because the cause of most sleep disorders was unknown. These 3 symptom-based categories are easily understood by physicians and are therefore useful for developing a differential diagnosis. The International Classification of Sleep Disorders, version 2, published in 2005 and currently undergoing revision, combines a symptomatic presentation (e.g., insomnia) with 1 organized in part on pathophysiology (e.g., circadian rhythms) and in part on body systems (e.g., breathing disorders). This organization of sleep disorders is necessary because of the varied nature and because the pathophysiology for many of the disorders is still unknown. The International Classification of Sleep Disorders, version 2 provides relevant diagnostic and epidemiological information on sleep disorders to more easily differentiate between the disorders.

Fibromyalgia syndrome and chronotype: late chronotypes are more affected

Sleep has strong links to the symptomology of fibromyalgia syndrome (FMS), a diffuse musculoskeletal pain disorder. Information about the involvement of the circadian clock is, however, sparse. In this study, 1548 individuals with FMS completed an online survey containing questions on demographics, stimulant consumption, sleep quality, well-being and subjective pain, chronotype (assessed by the Munich ChronoType Questionnaire, MCTQ), and FMS impact. Chronotype (expressed as the mid-sleep-point on free days, corrected for sleep deficit on workdays, MSF(sc)) significantly correlated with stress-ratings, so-called "memory failures in everyday life," fatigue, FMS impact, and depression but not with anxiety. When chronotypes were categorized into 3 groups (early, intermediate, late), significant group differences were found for sum scores of perceived stress, memory failures in everyday life, fatigue, FMS impact, and depression but not anxiety, with late chronotypes being more affected than early chronotypes. Sleepiness ratings were highest in early chronotypes. Challenges of sleep quality and subjective pain were significantly increased in both early and late chronotypes. The results show that according to their reports, late chronotypes are more affected by fibromyalgia.

Melatonin profile and its relation to circadian rhythm sleep disorders in Angelman syndrome patients

BACKGROUND

Sleep problems are known to be common in Angelman syndrome (AS), a neurodevelopmental disorder which is associated with an abnormality of chromosome 15q11-q13. However, the circadian aspect of sleep disorders in AS and an effective treatment for the disorder have yet to be established.

METHODS

We elucidated the sleep-wake patterns of AS patients and its relationship to the serum melatonin levels. The serum melatonin levels of 15 AS patients were measured every 4h for one day and the values were compared with those of age-matched controls. We also examined the effectiveness of the oral administration of melatonin on AS patients with circadian rhythm sleep disorders (CRSD).

RESULTS

A total of eight of the 15 AS patients had CRSD (irregular sleep-wake type, n=4; free-running type n=2; delayed sleep phase type, n=2). The nighttime serum melatonin levels of the AS patients were significantly lower than those of the controls at the measured time points during the night. The nocturnal melatonin levels were comparably low both in AS patients with and without CRSD except for the cases with delayed sleep phase type, which showed normal but delayed peak melatonin level. Six out of eight CRSD cases were given a daily dose of 1mg of melatonin between 18:00 and 19:00 regularly for three months. After receiving the treatment, the sleep patterns improved in four cases.

CONCLUSION

This study revealed a high prevalence of CRSD in AS patients, which may be related to abnormal serum melatonin profiles.

The management of sleep and circadian disturbance in patients with dementia

Sleep and circadian disturbances are common among patients with dementia. Symptomatic manifestations vary according to dementia subtype, with one commonly shared pattern--the irregular sleep-wake rhythm (ISWR), a circadian disorder characterized by an absence of the sleepwake cycle’s circadian synchronization. Hypothesized mechanisms of circadian rhythm disturbance include suprachiasmatic nucleus (SCN) circadian pacemaker damage, pineal gland and melatonin secretion alterations, and reduced zeitbeigers and decreased input to the SCN. Management options include prescribed sleep/wake scheduling, light therapy, melatonin, physical and social activity, and mixed modality. The mixed-modality approach is the most effective method in treating ISWR. Pharmacologic interventions are controversial, with no evidence supporting their effectiveness while associated with multiple side effects. They should be used with caution and only be considered as short-term therapy. All treatment strategies should be individualized to achieve the best outcomes.

Neurobiology, pathophysiology, and treatment of melatonin deficiency and dysfunction

Melatonin is a highly pleiotropic signaling molecule, which is released as a hormone of the pineal gland predominantly during night. Melatonin secretion decreases during aging. Reduced melatonin levels are also observed in various diseases, such as types of dementia, some mood disorders, severe pain, cancer, and diabetes type 2. Melatonin dysfunction is frequently related to deviations in amplitudes, phasing, and coupling of circadian rhythms. Gene polymorphisms of melatonin receptors and circadian oscillator proteins bear risks for several of the diseases mentioned. A common symptom of insufficient melatonin signaling is sleep disturbances. It is necessary to distinguish between symptoms that are curable by short melatonergic actions and others that require extended actions during night. Melatonin immediate release is already effective, at moderate doses, for reducing difficulties of falling asleep or improving symptoms associated with poorly coupled circadian rhythms, including seasonal affective and bipolar disorders. For purposes of a replacement therapy based on longer-lasting melatonergic actions, melatonin prolonged release and synthetic agonists have been developed. Therapies with melatonin or synthetic melatonergic drugs have to consider that these agents do not only act on the SCN, but also on numerous organs and cells in which melatonin receptors are also expressed.

CIRCADIAN PHASE RE-SETTING USING NONLINEAR OUTPUT-FEEDBACK CONTROL

Circadian rhythms occupy an important role in daily biological activities of living species. Circadian disorder is a phenomenon of circadian rhythms which occurs when internal rhythms cannot keep up with the changes of external environment rhythms. Changes of environmental rhythms, presented by the change of light/dark cycles or by irregular rhythms, result in phase shifts between internal and external rhythms. The existence of these phase shifts in longer term has negative effect to health. Therefore, in biological study of circadian rhythms, finding a method to recover the shifted phases to their normal rhythms, which is also the treatment of circadian disorder, is an important required task. In this paper, we propose a control design method to reset the circadian phases. The phase restoration is carried out by the synchronization of trajectories generated from a controlled model with the trajectories of a reference system via nonlinear control design using only one measurement. Both reference and controlled systems are based on a given 3rd order model of Neurospora circadian rhythms. The two other unknown states are estimated using a recently developed nonlinear observer for the output-feedback control.

Circadian and wakefulness-sleep modulation of cognition in humans

Cognitive and affective processes vary over the course of the 24 h day. Time of day dependent changes in human cognition are modulated by an internal circadian timekeeping system with a near-24 h period. The human circadian timekeeping system interacts with sleep-wakefulness regulatory processes to modulate brain arousal, neurocognitive and affective function. Brain arousal is regulated by ascending brain stem, basal forebrain (BF) and hypothalamic arousal systems and inhibition or disruption of these systems reduces brain arousal, impairs cognition, and promotes sleep. The internal circadian timekeeping system modulates cognition and affective function by projections from the master circadian clock, located in the hypothalamic suprachiasmatic nuclei (SCN), to arousal and sleep systems and via clock gene oscillations in brain tissues. Understanding the basic principles of circadian and wakefulness-sleep physiology can help to recognize how the circadian system modulates human cognition and influences learning, memory and emotion. Developmental changes in sleep and circadian processes and circadian misalignment in circadian rhythm sleep disorders have important implications for learning, memory and emotion. Overall, when wakefulness occurs at appropriate internal biological times, circadian clockwork benefits human cognitive and emotion function throughout the lifespan. Yet, when wakefulness occurs at inappropriate biological times because of environmental pressures (e.g., early school start times, long work hours that include work at night, shift work, jet lag) or because of circadian rhythm sleep disorders, the resulting misalignment between circadian and wakefulness-sleep physiology leads to impaired cognitive performance, learning, emotion, and safety.