Psychiatric aspects of jet lag: review and hypothesis

Dynamical analysis of the effects of circadian clock on the neurotransmitter dopamine

The circadian clock is an autonomous timing system that regulates the physiological and behavioral activities of organisms. Dopamine (DA) is an important neurotransmitter that is associated with many biological activities such as mood and movement. Experimental studies have shown that the circadian clock influences the DA system and disorders in the circadian clock lead to DA-related diseases. However, the regulatory mechanism of the circadian clock on DA is far from clear. In this paper, we apply an existing circadian-dopamine mathematical model to explore the effects of the circadian clock on DA. Based on numerical simulations, we find the disturbance of the circadian clock, including clock gene mutations, jet lag and light pulses, leads to abnormal DA levels. The effects of mutations in some clock genes on the mood and behavior of mice are closely related to DA disruptions. By sensitivity analysis of DA levels to parameter perturbation, we identify key reactions that affect DA levels, which provides insights into modulating DA disorders. Sudden changes in external light influence the circadian clock, bringing about effects on the DA system. Jet lag causes transient DA rhythm desynchronization with the environment and the influence of jet lag in different directions on DA level and phase varies. Light pulses affect the amplitude and phase shift of DA, which provides a promising method for treating DA disorders through light exposure. This study helps to better understand the impact of the circadian clock on the DA system and provides theoretical support for the treatment of DA disorders.

Longitudinal Relationships Between Depressive Symptom Severity and Phone-Measured Mobility: Dynamic Structural Equation Modeling Study

BACKGROUND

The mobility of an individual measured by phone-collected location data has been found to be associated with depression; however, the longitudinal relationships (the temporal direction of relationships) between depressive symptom severity and phone-measured mobility have yet to be fully explored.

OBJECTIVE

We aimed to explore the relationships and the direction of the relationships between depressive symptom severity and phone-measured mobility over time.

METHODS

Data used in this paper came from a major EU program, called the Remote Assessment of Disease and Relapse-Major Depressive Disorder, which was conducted in 3 European countries. Depressive symptom severity was measured with the 8-item Patient Health Questionnaire (PHQ-8) through mobile phones every 2 weeks. Participants' location data were recorded by GPS and network sensors in mobile phones every 10 minutes, and 11 mobility features were extracted from location data for the 2 weeks prior to the PHQ-8 assessment. Dynamic structural equation modeling was used to explore the longitudinal relationships between depressive symptom severity and phone-measured mobility.

RESULTS

This study included 2341 PHQ-8 records and corresponding phone-collected location data from 290 participants (age: median 50.0 IQR 34.0, 59.0) years; of whom 215 (74.1%) were female, and 149 (51.4%) were employed. Significant negative correlations were found between depressive symptom severity and phone-measured mobility, and these correlations were more significant at the within-individual level than the between-individual level. For the direction of relationships over time, Homestay (time at home) (φ=0.09, P=.01), Location Entropy (time distribution on different locations) (φ=-0.04, P=.02), and Residential Location Count (reflecting traveling) (φ=0.05, P=.02) were significantly correlated with the subsequent changes in the PHQ-8 score, while changes in the PHQ-8 score significantly affected (φ=-0.07, P<.001) the subsequent periodicity of mobility.

CONCLUSIONS

Several phone-derived mobility features have the potential to predict future depression, which may provide support for future clinical applications, relapse prevention, and remote mental health monitoring practices in real-world settings.

Assessing the impacts of ALAN and noise proxies on sleep duration and quality: evidence from a nation-wide survey in Israel

Sleep is a reversible state that sustains physiological and psychological processes in humans. As well established, individual-level factors, such as stress, smoking, drugs, and caffeine intake, reduce sleep duration and quality. However, studies of the effect of environmental risk factors, such as artificial light at night (ALAN) and noise, on sleep have been infrequent. Using records obtained from the 2017 Social Survey of Israel and combined with ALAN satellite data and various proxies for traffic noise, the present study aimed to determine how the combination of ALAN and traffic noise impact sleep duration and quality in urban areas. The increase of road density at the place of residence reduces average sleep duration by ~4.5% (~18 min.) and increases the frequency of reported sleep difficulties by ~3.5%, all other factors held equal. Similarly, an increase in ALAN exposure reduces average sleep duration by ~3% (~12 min) and increases the frequency of reported sleep difficulties by ~11%. The study also reveals a significant interaction between the two environmental risk factors in question, with the adverse impact of ALAN on sleep quality especially pronounced in high noise exposure areas.

Disrupted circadian rhythms and mental health

During the evolution of life, the temporal rhythm of our rotating planet was internalized in the form of circadian rhythms. Circadian rhythms are ~24h internal manifestations that drive daily patterns of physiology and behavior. These rhythms are entrained (synchronized) to the external environment, primarily by the light-dark cycle, and precisely controlled via molecular clocks located within the suprachiasmatic nucleus of the hypothalamus. Misalignment and/or disruption of circadian rhythms can have detrimental consequences for human health. Indeed, studies suggest strong associations between mental health and circadian rhythms. However, direct interactions between mood regulation and the circadian system are just beginning to be uncovered and appreciated. This chapter examines the relationship between disruption of circadian rhythms and mental health. The primary focus will be outlining the association between circadian disruption, in the form of night shift work, exposure to light at night, jet lag, and social jet lag, and psychiatric illness (i.e., anxiety, major depressive disorder, bipolar disorder, and schizophrenia). Additionally, we review animal models of disrupted circadian rhythms, which provide further evidence in support of a strong association between circadian disruption and affective responses. Finally, we discuss future directions for the field and suggest areas of study that require further investigation.

Substrain specific behavioral responses in male C57BL/6N and C57BL/6J mice to a shortened 21-hour day and high-fat diet

Altered circadian rhythms have negative consequences on health and behavior. Emerging evidence suggests genetics influences the physiological and behavioral responses to circadian disruption. We investigated the effects of a 21 h day (T = 21 cycle), with high-fat diet consumption, on locomotor activity, explorative behaviors, and health in male C57BL/6J and C57BL/6N mice. Mice were exposed to either a T = 24 or T = 21 cycle and given standard rodent chow (RC) or a 60% high-fat diet (HFD) followed by behavioral assays and physiological measures. We uncovered numerous strain differences within the behavioral and physiological assays, mainly that C57BL/6J mice exhibit reduced susceptibility to the obesogenic effects of (HFD) and anxiety-like behavior as well as increased circadian and novelty-induced locomotor activity compared to C57BL/6N mice. There were also substrain-specific differences in behavioral responses to the T = 21 cycle, including exploratory behaviors and circadian locomotor activity. Under the 21-h day, mice consuming RC displayed entrainment, while mice exposed to HFD exhibited a lengthening of activity rhythms. In the open-field and light-dark box, mice exposed to the T = 21 cycle had increased novelty-induced locomotor activity with no further effects of diet, suggesting daylength may affect mood-related behaviors. These results indicate that different circadian cycles impact metabolic and behavioral responses depending on genetic background, and despite circadian entrainment.

Are Owls and Larks Different When it Comes to Aggression? Genetics, Neurobiology, and Behavior

This review focuses on the contribution of circadian rhythms to aggression with a multifaceted approach incorporating genetics, neural networks, and behavior. We explore the hypothesis that chronic circadian misalignment is contributing to increased aggression. Genes involved in both circadian rhythms and aggression are discussed as a possible mechanism for increased aggression that might be elicited by circadian misalignment. We then discuss the neural networks underlying aggression and how dysregulation in the interaction of these networks evoked by circadian rhythm misalignment could contribute to aggression. The last section of this review will present recent human correlational data demonstrating the association between chronotype and/or circadian misalignment with aggression. With circadian rhythms and aggression being a burgeoning area of study, we hope that this review initiates more interest in this promising and topical area.

Circadian rhythm disruption and mental health

Circadian rhythms are internal manifestations of the solar day that permit adaptations to predictable environmental temporal changes. These ~24-h rhythms are controlled by molecular clockworks within the brain that are reset daily to precisely 24 h by exposure to the light-dark cycle. Information from the master clock in the mammalian hypothalamus conveys temporal information to the entire body via humoral and neural communication. A bidirectional relationship exists between mood disorders and circadian rhythms. Mood disorders are often associated with disrupted circadian clock-controlled responses, such as sleep and cortisol secretion, whereas disruption of circadian rhythms via jet lag, night-shift work, or exposure to artificial light at night, can precipitate or exacerbate affective symptoms in susceptible individuals. Evidence suggests strong associations between circadian rhythms and mental health, but only recently have studies begun to discover the direct interactions between the circadian system and mood regulation. This review provides an overview of disrupted circadian rhythms and the relationship to behavioral health and psychiatry. The focus of this review is delineating the role of disruption of circadian rhythms on mood disorders using human night shift studies, as well as jet lag studies to identify links. We also review animal models of disrupted circadian rhythms on affective responses. Lastly, we propose low-cost behavioral and lifestyle changes to improve circadian rhythms and presumably behavioral health.

Sleep duration and social jetlag are independently associated with anxious symptoms in adolescents

Although short total sleep time (TST) is associated with increased anxious symptoms in adolescents, it is unknown whether social jetlag, a misalignment between sleep timing on the weekend and school week, is independently associated with anxious symptoms. In the current study, sleep timing, anxious symptoms, and demographic information were assessed from 3097 adolescents (48% female, mean ± SD age 15.59 ± .77 years) from the age 15 wave of the Fragile Families and Child Wellbeing Study. Social jetlag was calculated as the absolute value of the midpoint of sleep on the weekend minus the midpoint of sleep during the school week. Anxious symptoms were measured through the 6-item anxiety subscale of the Brief Symptom Inventory 18. We assessed associations between sleep variables and anxious symptoms using multiple linear regression. Adjusted analyses controlled for sex, race/ethnicity, age in years, body mass index percentile, number of other children below the age of 18 in the household, and primary caregiver (PCG) married/cohabiting with youth's biological parent, PCG employment status, PCG household income and PCG education level. In fully adjusted models (R² = .034), school night TST (b = -.04, ∆R² = .005, p < .001) was negatively associated with anxiety symptoms, while social jetlag (b = .04, ∆R² = .009, p < .001) was positively and independently associated with anxiety symptoms. Findings indicate small associations of school night TST and social jetlag with anxious symptoms. Thus, maintenance of optimal emotional health in adolescents may require both sufficient sleep duration and regularity of sleep timing across the week.

Outdoor light at night and the prevalence of depressive symptoms and suicidal behaviors: A cross-sectional study in a nationally representative sample of Korean adults

BACKGROUND

Outdoor light at night (LAN) is an increasingly prevalent type of environmental pollution. Studies have demonstrated that outdoor LAN can disrupt circadian rhythms, potentially contributing to insomnia, cancer, cardiovascular disease, and metabolic changes in humans. We investigated the association of outdoor LAN with depressive symptoms and suicidal behaviors in South Korean adults.

METHODS

This study used data from the 2009 Korean Community Health Survey, a representative sample dataset. Study population consisted of 113,119 participants for the assessment of depressive symptoms and 152,159 participants for the assessment of suicidal behavior. Depressive symptoms were measured using the Korean version of the Center for Epidemiologic Studies Depression Scale (depressive symptoms, score of > 16). Suicidal behaviors were defined as the experience of suicidal ideation or attempt. Outdoor LAN was estimated by satellite data from the National Centers for Environmental Information.

RESULTS

Participants with depressive symptoms or history of suicidal behaviors were more likely to have exposure to outdoor LAN than those without depressive symptoms or suicidal behaviors. Compared with adults living in areas exposed to the lowest outdoor LAN, those living in areas exposed to the highest levels had higher likelihood depressive symptoms (OR = 1.29; 95% CI: 1.15-1.46) or suicidal behaviors (OR = 1.27; 95% CI: 1.16-1.39). Significant dose-response relationships were observed between outdoor LAN and the odds of depressive symptoms and suicidal behaviors.

CONCLUSION

Outdoor LAN was found to be significantly associated with depressive symptoms and suicidal behaviors, suggesting that it may be an environmental contributor to mental health problems.

Patients with mental problems - the most defenseless travellers

BACKGROUND

Severe mental illness occurring abroad is a difficult situation for patients, their families, and for the local medical community. Patients with mental problem are doublely stigmatized due to their mental illness and because they are foreigners in an unfamiliar country. The appropriate treatment is often delayed, while patients are often dealt with in a manner that violates their human rights. Moreover, repatriation - which is vital in this case - is often delayed due to the lack of international protocols for the transportation and treatment of mentally ill travelers.

METHODS

Authors analyzed several factors related to acute mental health problems during travel: the etiology of symptoms, the appropriate treatment possibilities abroad, and medical evacuation and repatriation of the psychotic patient. The article presents a brief review of travel-related mental disorders, the epidemiology of mental health issues faced by travelers, and the significance of pre-travel advice for these patients. The first problem is to recognize (and redress) the particular challenges faced by a psychotic patient in a strange country. The second challenge is to prepare the patients, often in a poor psychiatric state, for medical evacuation by commercial aircraft. Another important question is the best way to take the patient through customs and security control. All of these, as yet unresolved, issues can make the mental patient virtually defenseless.

CONCLUSIONS

Although timely repatriation of a mentally ill patient is vital and urgent, most travel insurance policies exclude treatment and repatriation costs incurred due to acute mental illness. The high cost of treatment and repatriation must be paid by the patient or their family, which could lead to severe financial strain or insolvency. Changing the approaches taken by the local mental health care community, police, airport security, and insurance companies remain a challenge for psychiatrists.

Circadian clock and stress interactions in the molecular biology of psychiatric disorders

Many psychiatric disorders are characterized by circadian rhythm abnormalities, including disturbed sleep/wake cycles, changes in locomotor activity, and abnormal endocrine function. Animal models with mutations in circadian "clock genes" commonly show disturbances in reward processing, locomotor activity and novelty seeking behaviors, further supporting the idea of a connection between the circadian clock and psychiatric disorders. However, if circadian clock dysfunction is a common risk factor for multiple psychiatric disorders, it is unknown if and how these putative clock abnormalities could be expressed differently, and contribute to multiple, distinct phenotypes. One possible explanation is that the circadian clock modulates the biological responses to stressful environmental factors that vary with an individual's experience. It is known that the circadian clock and the stress response systems are closely related: Circadian clock genes regulate the physiological sensitivity to and rhythmic release of glucocorticoids (GC). In turn, GCs have reciprocal effects on the clock. Since stressful life events or increased vulnerability to stress are risk factors for multiple psychiatric disorders, including post-traumatic stress disorder (PTSD), attention deficit hyperactivity disorder (ADHD), bipolar disorder (BD), major depressive disorder (MDD), alcohol use disorder (AUD) and schizophrenia (SCZ), we propose that modulation of the stress response is a common mechanism by which circadian clock genes affect these illnesses. Presently, we review how molecular components of the circadian clock may contribute to these six psychiatric disorders, and present the hypothesis that modulation of the stress response may constitute a common mechanism by which the circadian clock affects multiple psychiatric disorders.

Influence of the modern light environment on mood

Humans and other organisms have adapted to a consistent and predictable 24-h solar cycle, but over the past ~130 years the widespread adoption of electric light has transformed our environment. Instead of aligning behavioral and physiological processes to the natural solar cycle, individuals respond to artificial light cycles created by social and work schedules. Urban light pollution, night shift work, transmeridian travel, televisions and computers have dramatically altered the timing of light used to entrain biological rhythms. In humans and other mammals, light is detected by the retina and intrinsically photosensitive retinal ganglion cells project this information both to the circadian system and limbic brain regions. Therefore, it is possible that exposure to light at night, which has become pervasive, may disrupt both circadian timing and mood. Notably, the rate of major depression has increased in recent decades, in parallel with increasing exposure to light at night. Strong evidence already links circadian disruption to major depression and other mood disorders. Emerging evidence from the past few years suggests that exposure to light at night also negatively influences mood. In this review, we discuss evidence from recent human and rodent studies supporting the novel hypothesis that nighttime exposure to light disrupts circadian organization and contributes to depressed mood.

Effect of airline travel on performance: a review of the literature

The need for athletes to travel long distances has spurred investigation into the effect of air travel across multiple time zones on athletic performance. Rapid eastward or westward travel may negatively affect the body in many ways; therefore, strategies should be employed to minimise these effects which may hamper athletic performance. In this review, the fundamentals of circadian rhythm disruption are examined along with additional effects of airline travel including jet lag, sleep deprivation, travel at altitude and nutritional considerations that negatively affect performance. Evidence-based recommendations are provided at the end of the manuscript to minimise the effects of airline travel on performance.

Circadian disruption and remedial interventions: effects and interventions for jet lag for athletic peak performance

Jet lag has potentially serious deleterious effects on performance in athletes following transmeridian travel, where time zones are crossed eastwards or westwards; as such, travel causes specific effects related to desynchronization of the athlete's internal body clock or circadian clock. Athletes are particularly sensitive to the effects of jet lag, as many intrinsic aspects of sporting performance show a circadian rhythm, and optimum competitive results require all aspects of the athlete's mind and body to be working in tandem at their peak efficiency. International competition often requires transmeridian travel, and competition timings cannot be adjusted to suit individual athletes. It is therefore in the interest of the individual athlete and team to understand the effects of jet lag and the potential adaptation strategies that can be adopted. In this review, we describe the underlying genetic and physiological mechanisms controlling the circadian clock and its inherent ability to adapt to external conditions on a daily basis. We then examine the fundamentals of the various adaptation stimuli, such as light, chronobiotics (e.g. melatonin), exercise, and diet and meal timing, with particular emphasis on their suitability as strategies for competing athletes on the international circuit. These stimuli can be artificially manipulated to produce phase shifts in the circadian rhythm to promote adaptation in the optimum direction, but care must be taken to apply them at the correct time and dose, as the effects produced on the circadian rhythm follow a phase-response curve, with pronounced shifts in direction at different times. Light is the strongest realigning stimulus and careful timing of light exposure and avoidance can promote adjustment. Chronobiotics such as melatonin can also be used to realign the circadian clock but, as well as timing and dosage issues, there are also concerns as to its legal status in different countries and with the World Anti-Doping Agency. Experimental data concerning the effects of food intake and exercise timing on jet lag is limited to date in humans, and more research is required before firm guidelines can be stated. All these stimuli can also be used in pre-flight adaptation strategies to promote adjustment in the required direction, and implementation of these is described. In addition, the effects of individual variability at the behavioural and genetic levels are also discussed, along with the current limitations in assessment of these factors, and we then put forward three case studies, as examples of practical applications of these strategies, focusing on adaptations to travel involving competition in the Rugby Sevens World Cup and the 2016 Summer Olympics in Rio de Janeiro, Brazil. Finally, we provide a list of practice points for optimal adaptation of athletes to jet lag.

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.

Jet lag and psychotic disorders

Jet lag syndrome appears after multiple time zone transitions as bodily rhythms shift out of phase with the local environment. The possible psychiatric complications of jet lag have been underinvestigated. In the present review, the symptoms of jet lag in the general population, the chronobiological aspects of psychosis, as well as a possible correlation between jet lag and psychosis are discussed. The conclusions are that jet lag, through disruption of biological rhythm and probably sleep deprivation, may yield an exacerbation of existing psychotic conditions. The evidence concerning the appearance of de novo psychosis triggered by jet lag is inconsistent and far from convincing.

Neurochemical and neuropharmacological aspects of circadian disruptions: an introduction to asynchronization

Circadian disruptions are common in modern society, and there is an urgent need for effective treatment strategies. According to standard diagnostic criteria, most adolescents showing both insomnia and daytime sleepiness are diagnosed as having behavioral-induced sleep efficiency syndrome resulting from insomnia due to inadequate sleep hygiene. However, a simple intervention of adequate sleep hygiene often fails to treat them. As a solution to this clinical problem, the present review first overviews the basic neurochemical and neuropharmachological aspects of sleep and circadian rhythm regulation, then explains several circadian disruptions from similar viewpoints, and finally introduces the clinical notion of asynchronization. Asynchronization is designated to explain the pathophysiology/pathogenesis of exhibition of both insomnia and hypersomnia in adolescents, which comprises disturbances in various aspects of biological rhythms. The major triggers for asynchronization are considered to be a combination of light exposure during the night, which disturbs the biological clock and decreases melatonin secretion, as well as a lack of light exposure in the morning, which prohibits normal synchronization of the biological clock to the 24-hour cycle of the earth and decreases the activity of serotonin. In the chronic phase of asynchronization, involvement of both wake- and sleep-promoting systems is suggested. Both conventional and alternative therapeutic approaches for potential treatment of asynchronization are suggested.

[Psychiatric patient: the most vulnerable traveller]

Authors analyse questions of medical evacuation of the psychotic patient from abroad to homeland. This task can be considered the most difficult problem for the attending physician and the escorting medical team as well. The main challenge is to recognise the psychotic patient in a foreign country with a different health-care system and to overcome the language barrier and the different cultural background. The second issue is to prepare the patients - who are usually in a poor condition - for the medical evacuation by commercial aircraft. Another important issue is to take the patient through the strict security control. All of these (partially unsolved) problems make the mentally ill patient defenceless. Although the repatriation of a mentally ill patient is vital and urgent, travel insurance policy mostly excludes to cover the cost of treatment and repatriation. The high cost of treatment and repatriation of the patient should be paid by the patient or the family, who are often in the position of insolvency. In this paper authors present the history of a patient and give a brief review on travel-related mental disorders, the epidemiology of mental alterations during travel as well as the problems of appropriate evacuation. Authors conclude that there is a need for a better approach of the airport authorities and insurance decision makers to the mentally ill patient travelling abroad.

Sleep health and asynchronization

Recent surveys in Japan reported that more than half of children interviewed complained of daytime sleepiness, approximately one quarter reported insomnia, and some complained of both nocturnal insomnia and daytime sleepiness. To explain the pathophysiology of this type of sleep disturbance, a novel clinical concept of asynchronization has been proposed. Asynchronization involves disturbances in various aspects of biological rhythms that normally exhibit circadian oscillations. The putative major triggers for asynchronization include a combination of nighttime light exposure, which can disturb the biological clock and decrease melatonin secretion, and a lack of morning light exposure, which can prohibit normal synchronization of the biological clock to a 24-h cycle and decrease activity in the serotonergic system. The early phase of asynchronization may be caused by inadequate sleep hygiene, is likely to be functional, and to be relatively easily resolved by establishing a regular sleep-wakefulness cycle. However, without adequate intervention, these disturbances may gradually worsen, resulting into the chronic phase. No single symptom appears to be specific for the clinical phases, and the chronic phase is defined in terms of the response to interventions. The factors causing the transition from the early to chronic phase of asynchronization and those producing the difficulties of recovering patients with the chronic phase of asynchronization are currently unclear.

Shift work, jet lag, and female reproduction

Circadian rhythms and "clock gene" expression are involved in successful reproductive cycles, mating, and pregnancy. Alterations or disruptions of biological rhythms, as commonly occurs in shift work, jet lag, sleep deprivation, or clock gene knock out models, are linked to significant disruptions in reproductive function. These impairments include altered hormonal secretion patterns, reduced conception rates, increased miscarriage rates and an increased risk of breast cancer. Female health may be particularly susceptible to the impact of desynchronizing work schedules as perturbed hormonal rhythms can further influence the expression patterns of clock genes. Estrogen modifies clock gene expression in the uterus, ovaries, and suprachiasmatic nucleus, the site of the primary circadian clock mechanism. Further work investigating clock genes, light exposure, ovarian hormones, and reproductive function will be critical for indentifying how these factors interact to impact health and susceptibility to disease.

Lithium and genetic inhibition of GSK3beta enhance the effect of methamphetamine on circadian rhythms in the mouse

Lithium, a drug commonly used to treat mood disorders, and the psychostimulant methamphetamine are both capable of altering circadian rhythmicity. Although the actions of lithium on the circadian system are thought to occur through inhibition of glycogen synthase kinase-3beta (GSK3beta), the mechanism by which methamphetamine alters circadian rhythms is unknown. We tested the effects of concurrent methamphetamine and lithium treatment on the circadian wheel-running behavior of mice. Methamphetamine alone lengthened both the active duration and the free-running period of locomotor activity in animals housed in constant conditions. Administering lithium enhanced the period-lengthening effects of methamphetamine in animals housed in constant darkness. This effect was even more pronounced when animals were housed in constant light. Lithium increased both methamphetamine intake and serum levels of methamphetamine, possibly contributing to the effects on circadian behavior. We also tested the effect of methamphetamine in mutant mice possessing only one allele for Gsk3beta. These animals, when treated with methamphetamine, responded like wild-type mice treated with a combination of methamphetamine and lithium, displaying long, free-running rhythms. These data, together with many others in the literature, point to a complicated interaction between the circadian system and the development and possible treatment of psychopathologies such as bipolar disorder and drug addiction.

A newly proposed disease condition produced by light exposure during night: asynchronization

The bedtime of preschoolers/pupils/students in Japan has become progressively later with the result sleep duration has become progressively shorter. With these changes, more than half of the preschoolers/pupils/students in Japan recently have complained of daytime sleepiness, while approximately one quarter of junior and senior high school students in Japan reportedly suffer from insomnia. These preschoolers/pupils/students may be suffering from behaviorally induced insufficient sleep syndrome due to inadequate sleep hygiene. If this diagnosis is correct, they should be free from these complaints after obtaining sufficient sleep by avoiding inadequate sleep hygiene. However, such a therapeutic approach often fails. Although social factors are often involved in these sleep disturbances, a novel clinical notion--asynchronization--can further a deeper understanding of the pathophysiology of these disturbances. The essence of asynchronization is a disturbance in various aspects (e.g., cycle, amplitude, phase and interrelationship) of the biological rhythms that normally exhibit circadian oscillation, presumably involving decreased activity of the serotonergic system. The major trigger of asynchronization is hypothesized to be a combination of light exposure during the night and a lack of light exposure in the morning. In addition to basic principles of morning light and an avoidance of nocturnal light exposure, presumable potential therapeutic approaches for asynchronization involve both conventional ones (light therapy, medications (hypnotics, antidepressants, melatonin, vitamin B12), physical activation, chronotherapy) and alternative ones (kampo, pulse therapy, direct contact, control of the autonomic nervous system, respiration (qigong, tanden breathing), chewing, crawling). A morning-type behavioral preference is described in several of the traditional textbooks for good health. The author recommends a morning-type behavioral lifestyle as a way to reduce behavioral/emotional problems, and to lessen the likelihood of falling into asynchronization.

A study of the association between sleep habits and problematic behaviors in preschool children

This preliminary study examined the association between sleep habits and problematic behaviors in healthy preschool children using an internationally standardized method. Two groups of 4-6-yr-old healthy Japanese children were recruited. Children in Group A (n=68) met one or more of the following three conditions: they went out from their home with adults after 21:00 h two or more times a week, they went to bed after 23:00 h four or more times a week, and they returned home after 21:00 h three or more times a week, while those in Group B (n=67) met none of these conditions. Sleep-wake logs and the Child Behavior Checklist (CBCL)/4-18 were completed daily for two weeks. The CBCL consists of questions with 113 items categorized into eight subscale items: (I) Withdrawn, (II) Somatic complaints, (III) Anxious/depressed, (IV) Social problems, (V) Thought problems, (VI) Attention problems, (VII) Delinquent behavior, and (VIII) Aggressive behavior. Internalizing (I+II+III), externalizing (VII+VIII), and total scale scores were also derived. Generally, the higher the score, the greater the likelihood of problematic behaviors in that scale. We compared both the CBCL scores and distribution of the CBCL score-determined clinical classification of behavior (normal, borderline, and abnormal) between the groups. Correlation coefficients between CBCL scores and each of the seven indices of the studied sleep habits (wake-up times, bedtimes, nocturnal sleep duration, nap duration, total sleep duration, and range of variation in wake-up and bedtime) were also assessed. Group A children showed significantly shorter average nocturnal sleep, nap, and total sleep duration, significantly later average bedtimes and wake-up times, and a significantly greater range of variation in bedtimes and wake-up times than Group B children. The CBCL score of the total scale was significantly higher in Group A than Group B children. The distribution of the clinical classifications of behavior between the two groups showed no significant differences. Although nocturnal sleep, nap, and total sleep duration did not correlate with total CBCL score, it showed a high positive correlation with wake-up times, bedtimes, and ranges of variation in both wake-up and bed times. The distribution of the clinical classification for the total scale showed significant differences between early and late risers, and also between regular and irregular sleepers. The number of children classified as normal for the total scale score was higher in early risers and regular sleepers than in late risers and irregular sleepers. Preschool children of Group A, late risers, late sleepers, irregular risers, and irregular sleepers were likely to show problematic behaviors.

Electroconvulsive shock alters the rat overt rhythms of motor activity and temperature without altering the circadian pacemaker

The hypothetical relationship between circadian rhythms alterations and depression has prompted studies that examine the resultant effects of various antidepressants. Electroconvulsive therapy (ECT) exerts significant antidepressant effects that have been modelled in the laboratory via the use of electroconvulsive shock (ECS) in rats. However, data on the effects of ECT or ECS vis-à-vis the circadian rhythms remain scarce. Thus, we report here the effects of acute and chronic ECS administration on the temperature and motor activity circadian rhythms of rats. The motor activity and core body temperature of rats were continuously recorded to determine the circadian rhythms. We carried out three experiments. In the first, we analyzed the effects of acute ECS on both the phase and period when applied at different times of the subjective day. In the second and third experiments ECS was nearly daily applied to rats for 3 weeks: respectively, under dim red light, which allows a robust free-running circadian rhythm; and under light-dark cycles of 22 h (T22), a setting that implies dissociation in the circadian system. Acute ECS does not modify the phase or the period of circadian rhythms. Chronic administration of ECS produces an increase in motor activity and temperature, a decrease in the amplitude of circadian rhythms, although the period of the free-running rhythm remains unaffected. In conclusion, while chronic ECS does alter the overt rhythms of motor activity and temperature, it does not modify the functioning of the circadian pacemaker.

A book of ideas collected from Medical Hypotheses: Death can be cured by Roger Dobson

A new collection of ideas from Medical Hypotheses by Roger Dobson is entitled Death can be cured and 99 other Medical Hypotheses. It consists of humorous summaries of Medical Hypotheses articles from the past 30 years. The book's humour derives mainly from the subject matter, although sometimes also from the 'unconventional' approach of the authors with respect to matters such as evidence, argument or inference. Medical Hypotheses has generated such a lot of apparently- or actually-bizarre ideas because it aims to be open to potentially revolutionary science. The journal's official stance is that more harm is done by a failure to publish one idea that might have been true, than by publishing a dozen ideas that turn out to be false. Bizarre ideas tend to catch attention, and may stimulate a valuable response--even when a paper is mostly-wrong. A paper may be flawed but still contain the germ of an idea that can be elaborated and developed. The journal review process is susceptible to both false positives and false negatives. False positives occur when we publish an idea that is wrong; false negatives occur when we fail to publish an important idea that is right, and a potential scientific breakthrough never happens. False positives are more obvious, since the paper will be ignored, refuted, or fail to be replicated--and often attracts criticism and controversy. Editors may therefore take the more cautious path of avoiding false positives more assiduously than false negatives; however, this policy progressively favours less-ambitious science. Consequently, in Medical Hypotheses the 'set point' of risk is nearer to the false positive end of the spectrum than for most journals - and the publication of many apparently-bizarre papers is a natural consequence of this policy.

Circadian dependence of corticosterone release to light exposure in the rat

Previous studies have demonstrated a positive correlation between glucocorticoid levels and circadian reentrainment time following a shift in the light:dark (LD) cycle. We conducted a series of experiments to examine the circadian dependence of the corticosterone (CORT) response to light. Exp. 1 measured CORT release in rats exposed to light at six timepoints. Light presented during the subjective night increased CORT (p<0.05), while light presented during the subjective day did not. In Exp. 2, we documented the time course of the CORT response to light in entrained animals. Rats exposed to light at zeitgeber time (ZT) 18 had a maximal increase in CORT levels following 60 min of stimulus presentation (p<0.05). There was also an increase in adrenocorticotropic hormone following 15 min of light at ZT18 (p<0.05). In an effort to elucidate the effect of changes in the LD cycle on the circadian profile of CORT, Exp. 3 followed the CORT rhythm (in cerebrospinal fluid) of rats prior to and following a shift in the LD cycle. The CORT nadir was elevated following a 6 h photic advance (p<0.05), as was the mean CORT concentration during the peak phase (p<0.05). Most components of the circadian CORT rhythm, however, failed to show an immediate shift towards the change in the light cycle. Together, these data support the hypothesis that a photic phase-shift results in elevated CORT levels, while the rhythm of CORT secretion is robust against changes in the photic environment.

The role of mammalian circadian proteins in normal physiology and genotoxic stress responses

The last two decades have significantly advanced our understanding of the organization of the circadian system at all levels of regulation-molecular, cellular, tissue, and systemic. It has been recognized that the circadian system represents a complex temporal regulatory network, which plays an important role in synchronizing various biological processes within an organism and coordinating them with the environment. It is believed that deregulation of this synchronization may result in the development of various pathologies. However, recent studies using various circadian mutant mouse models have demonstrated that at least some of the components of the molecular oscillator are actively involved in physiological processes not directly related to their role in the circadian clock. The growing amount of evidence suggests that, in addition to their circadian function, circadian proteins are important in maintaining tissue homeostasis under normal and stress conditions. In this chapter, we will summarize recent data about the regulation of the mammalian molecular circadian oscillator and will focus on a new role of the circadian system and individual circadian proteins in the organism's physiology and response to genotoxic stress in connection with diseases treatment and prevention.

Psychiatric aspects of organic sleep disorders

In recent years, a number of studies have attempted to characterize psychological disturbances related to various sleep disorders. The objective of this type of research is to investigate the possibility that psychopathology may represent an etiological factor, a complication, and/or a target for treatment. In addition, disordered sleep can present itself in a complex and atypical fashion in which the primary sleep-related component may not be immediately apparent. This article reviews the evidence for a relationship between organic sleep disorders and psychiatric morbidity. Generally, it can be concluded that organic sleep disorders have a profound negative impact on most domains of health-related quality of life. Results for the sleep disorders that have been studied (narcolepsy idiopathic hypersomnia, sleep apnea/hypopnea syndrome, restless legs syndrome, periodic limb movement disorder, and circadian sleep disorders) show strong evidence for an association with mood disorders. After treatment, depression scores may or may not improve to the level of population norms, suggesting that this relationship is more complex than one of mere cause and effect.

Association study of eight circadian genes with bipolar I disorder, schizoaffective disorder and schizophrenia

We hypothesize that circadian dysfunction could underlie, at least partially, the liability for bipolar 1 disorder (BD1). Our hypothesis motivated tests for the association between the polymorphisms of genes that mediate circadian function and liability for BD1. The US Caucasian patients with BD1 (DSM-IV criteria) and available parents were recruited from Pittsburgh and surrounding areas (n = 138 cases, 196 parents) and also selected from the NIMH Genetics Collaborative Initiative (n = 96 cases, 192 parents). We assayed 44 informative single-nucleotide polymorphisms (SNPs) from eight circadian genes in the BD1 samples. A population-based sample, specifically cord blood samples from local live births, served as community-based controls (n = 180). It was used as a contrast for genotype and haplotype distributions with those of patients. US patients with schizophrenia/schizoaffective disorder (SZ/SZA, n = 331) and available parents from Pittsburgh (n = 344) were assayed for a smaller set of SNPs based on the results from the BD1 samples. Modest associations with SNPs at ARNTL (BmaL1) and TIMELESS genes were observed in the BD1 samples. The associations were detected using family-based and case-control analyses, albeit with different SNPs. Associations with TIMELESS and PERIOD3 were also detected in the Pittsburgh SZ/SZA group. Thus far, evidence for association between specific SNPs at the circadian gene loci and BD1 is tentative. Additional studies using larger samples are required to evaluate the associations reported here.

Restraint stress delays reentrainment in male and female diurnal and nocturnal rodents

A temporary loss of normal circadian entrainment, such as that associated with shift work and transmeridian travel, can result in an array of detrimental symptoms, making rapid reentrainment of rhythmicity essential. While there is a wealth of literature examining the effects of stress on the entrained circadian system, less is known about the influence of stress on circadian function following a phase shift of the light: dark (LD) cycle. The authors find that recovery of locomotor activity synchronization is altered by restraint stress in the diurnal rodent Octodon degus (degu) and the nocturnal rat. In the first experiment, degus were subjected to a 6-h phase advance of the LD cycle. Sixty minutes after the new lights-on, animals underwent 60 min of restraint stress. The number of days it took each animal to reentrain its activity rhythms to the new LD cycle was recorded and compared to the number of days it took the animal to reentrain under control conditions. When subjected to restraint stress, degus took 30% longer to reentrain their activity rhythms (p < 0.01). In a second experiment, rats underwent a similar experimental paradigm. As with the degus, stress significantly delayed the reentrainment of rats' activity rhythms (p < 0.01). There was no interaction between sex and stress on the rate of reentrainment for either rats or degus. Furthermore, there was no effect of stress on the free-running activity rhythm of degus, suggesting that the effect of stress on reentrainment rate is not secondary to alterations of period length. Together, these data point to a detrimental effect of stress on recovery of entrainment of circadian rhythms, which is independent of activity niche and sex.

24-hour pituitary and adrenal hormone profiles in chronic fatigue syndrome

OBJECTIVES

Disturbances of neuroendocrine function, particularly the hypothalamo-pituitary-adrenal (HPA) axis, have been implicated in the pathophysiology of chronic fatigue syndrome (CFS). However, few studies have attempted to measure blood levels of pituitary or adrenal hormones across a whole 24-hour period in CFS, and those that did so have used infrequent sampling periods. Our aim was to assess 24-hour pituitary and adrenal function using frequent blood sampling.

METHODS

We recruited 15 medication-free patients with CFS without comorbid psychiatric disorder and 10 healthy control subjects. Blood samples were collected over 24 hours and assayed for cortisol, corticotropin (ACTH), growth hormone (GH), and prolactin (PRL) levels on an hourly basis during daytime hours (10 am to 10 pm) and every 15 minutes thereafter (10 pm to 10 am).

RESULTS

Repeated-measures analyses of variance were undertaken using hormone levels averaged over 2-hour blocks to smooth curves by reducing the influence of sample timing relative to secretory burst. For ACTH, there was both a main effect of group, suggesting reduced mean ACTH secretion in patients with CFS over the whole monitoring period, and a group-by-time interaction, suggesting a differential pattern of ACTH release. Post hoc analysis showed reduced ACTH levels in CFS during the 8 am to 10 am period. In contrast, there were no significant abnormalities in the levels of cortisol, GH, and PRL in patients with CFS over the full cycle compared with control subjects. Cosinor analysis found no differences in the cortisol circadian rhythm parameters, but the ACTH rhythm did differ, patients with CFS showing an earlier acrophase.

CONCLUSIONS

Patients with CFS demonstrated subtle alterations in HPA axis activity characterized by reduced ACTH over a full circadian cycle and reduced levels during the usual morning physiological peak ACTH secretion. This provides further evidence of subtle dysregulation of the HPA axis in CFS. Whether this dysregulation is a primary feature of the illness or instead represents a biologic effect secondary to having the illness itself remains unclear.

Inhibiting cortisol response accelerates recovery from a photic phase shift

Jetlag results when a temporary loss of circadian entrainment alters phase relationships among internal rhythms and between an organism and the outside world. After a large shift in the light-dark (LD) cycle, rapid recovery of entrainment minimizes the negative effects of internal circadian disorganization. There is evidence in the existing literature for an activation of the hypothalamic-pituitary-adrenal (HPA) axis after a photic phase shift, and it is possible that the degree of HPA-axis response is a determining factor of reentrainment time. This study utilized a diurnal rodent, Octodon degus, to test the prediction that the alteration of cortisol levels would affect the reentrainment rate of circadian locomotor rhythms. In experiment 1, we examined the effects of decreased cortisol (using metyrapone, an 11beta-hydroxylase inhibitor) on the rate of running-wheel rhythm recovery after a 6-h photic phase advance. Metyrapone treatment significantly shortened the length of time it took animals to entrain to the new LD cycle (11.5% acceleration). In experiment 2, we examined the effects of increased cortisol on the rate of reentrainment after a 6-h photic phase advance. Increasing plasma cortisol levels increased the number of days (8%) animals took to reentrain running-wheel activity rhythms, but this effect did not reach significance. A third experiment replicated the results of experiment 1 and also demonstrated that suppression of HPA activity via dexamethasone injection is capable of accelerating reentrainment rates by approximately 33%. These studies provide support for an interaction between the stress axis and circadian rhythms in determining the rate of recovery from a phase shift of the LD cycle.

Confusion in travellers

Acute onset long haul in-flight confusion, restlessness, disorientation and abnormal behaviour in a 24 year old lady who had recent typhoid fever is reported. Confusion in travelers within the context of infections, including typhoid psychosis, and other causes, is discussed to enlighten practitioners on the problem, and ensuing potential medico-legal and ethical issues.

Psychiatric intervention for Japanese Nationals in New York

This study examined the characteristics of Japanese patients who required psychiatric intervention through the Consulate-General Japan in New York. The findings show that 61.5% of cases were tourists in contrast with 38.5% who were residents. Seventy three point one percent of all cases had psychiatric disorders prior to traveling to the United States. Seventy one point two had schizophrenia, and 48.1% required intervention within one week stay in the United States. The study indicated cultural elements had little influence on their psychiatric crises. The dominant cases, which were schizophrenics who traveled because of their delusional symptoms, were consistent with cases of "voyage pathologique". It was also suggested that cases with personality disorders are increasing in number. And we inferred that cases with substance-related disorders, particularly among young illegal residents, must be present in greater numbers.