Circadian Rhythm and Personality Profile in Juvenile Myoclonic Epilepsy

Juvenile Myoclonic Epilepsy (JME) is a prototype of idiopathic generalized epilepsy and is characterized by a strong genetic predisposition. According to clinical observations by Janz and Christian (1), the syndrome is associated with a characteristic sleep/wake rhythm and a typical personality profile. These features have subsequently been interpreted as a mild frontal lobe behavior syndrome. Recent neuropsychological and imaging studies confirmed mesiofrontal and prefrontal dysfunction in JME. We studied 20 patients with JME and a matched comparison group with temporal lobe epilepsy (TLE) using standardized questionnaires with respect to the sleep-wake rhythm and with respect to personality profiles. We confirmed the characteristic circadian rhythm in JME with the tendency to go to bed later at night, to get up later in the morning, and to feel fit at a later time during the day compared to patients with TLE. With the exception of some subanalyses we did not find evidence for a specific personality profile in JME.

Who is pre-occupied with sleep? A comparison of attention bias in people with psychophysiological insomnia, delayed sleep phase syndrome and good sleepers using the induced change blindness paradigm

Cognitive models of insomnia suggest that selective attention may be involved in maintaining the disorder. However, direct assessment of selective attention is limited. Using the inducing change blindness (ICB) paradigm we aimed to determine whether there is attentional preference for sleep-related stimuli in psychophysiological insomnia (PI) relative to delayed sleep phase syndrome (DSPS) and good sleepers (GS). In the ICB task, a visual scene, comprising both sleep-related and neutral stimuli, 'flickers' back and forth with one element (sleep or neutral) of the scene changing between presentations. Therefore, a 2 x 3 totally between-participants design was employed. The dependent variable was the number of flickers it took for the participant to identify the change. Ninety individuals (30 per group) were classified using ICSD-R criteria, self-report diaries and wrist actigraphy. As predicted, PI detected a sleep-related change significantly quicker than DSPS and GS, and significantly quicker than a sleep-neutral change. Unexpectedly, DSPS detected a sleep-related change significantly quicker than GS. No other differences were observed between the two controls. These results support the notion that there is an attention bias to sleep stimuli in PI, suggesting that selective attention tasks such as the ICB may be a useful objective index of cognitive arousal in insomnia. The results also suggest that there may be an element of sleep preoccupation associated with DSPS. Results are discussed with reference to other experiments on attentional processing in insomnia.

Sleepiness and head movements

Sleepiness in working life is critical and strongly associated to work related accidents. The relationship between sleepiness and head movements is poorly investigated. The pattern of head movements over time was investigated in a laboratory study with ten subjects either sleep-deprived or rested. Head movements were obtained by an inclinometer placed on the subject's forehead, and the recording was continuous. Results show that subjects when sleep-deprived moved their head more and had more extreme head movements compared to when rested. An increase of the velocity and the number of extreme head movements over time were noted when the subjects were sleep-deprived and when rested. The increase of head movements was more linear over time in the rested condition, whereas in sleep-deprived conditions most of the increase appeared during the first hour. No significant differences of between forward-backward movements and left-right movements could be found. When rested, the changes in head movements correlated with ratings of sleepiness, EEG activity, and heart rate variability. Head movements can be a used as an indicator of sleepiness.

Circadian Regulation of Arousal: Role of the Noradrenergic Locus Coeruleus System and Light Exposure

STUDY OBJECTIVES

Noradrenergic locus coeruleus (LC) neurons regulate arousal. Previous studies have shown that noradrenergic LC neurons exhibit a circadian rhythm in impulse activity, which peaks during the active period. This is mediated by an indirect circuit projection from the suprachiasmatic nucleus (SCN) to the LC. Here we sought to evaluate the hypothesis that the LC regulates the circadian properties of the sleep-wake cycle.

DESIGN

Sprague-Dawley rats maintained on a light-dark (LD) schedule or in constant darkness (DD) for 3 to 4 weeks were treated with DSP-4, a neurotoxic agent specific for noradrenergic-LC projections. Vigilance states were analyzed before and 3 weeks after LC lesion. The DSP-4 lesion was verified by immunohistochemistry of noradrenergic fibers in the frontal cortex.

SETTING

University of Pennsylvania.

PATIENTS OR PARTICIPANTS

N/A.

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

DSP-4 decreased the amplitude of the sleep-wake rhythm in LD animals by significantly decreasing wakefulness and increasing sleep during the active period. However, DSP-4 had no effect on the sleep-wake cycle of DD animals. Moreover, DD itself decreased the amplitude of the sleep-wake cycle similar to that of the neurotoxic lesion of the noradrenergic system in LD animals. Analysis of noradrenergic fiber staining in the frontal cortex revealed that this effect was associated with fewer fibers or boutons in nonlesioned DD rats than in nonlesioned LD animals.

CONCLUSIONS

Noradrenergic LC neurons provide a circadian regulation of the sleep-wake cycle, and the maintenance of LC function depends on light exposure. Light deprivation induces a loss of noradrenergic fibers, which in turn decreases the amplitude of the sleep-wake rhythm.

Light, dark, and melatonin: emerging evidence for the importance of melatonin in ocular physiology

Melatonin is a hormone, which is mainly produced by the pineal gland, a vestigial eye. Rather than the rods and cones, it is a newly discovered subgroup of photosensitive retinal ganglion cells, which is responsible for mediating the light-dark cycles, thus regulating melatonin's secretion. One of the correlates of the circadian rhythm of melatonin release is the habitual sleep pattern. Patients with circadian rhythm sleep disorders, including some blind patients with no light-induced suppression of melatonin, benefit from melatonin treatment. Melatonin is synthesized in the retina, lens, ciliary body as well as other parts of the body. In this review, we discuss the physiological roles of melatonin in the eye, as well as the potential therapeutic avenues currently under study.

The brain's master circadian clock: implications and opportunities for therapy of sleep disorders

The suprachiasmatic nuclei (SCN) residing in the anterior hypothalamus maintains a near-24-h rhythm of electrical activity, even in the absence of environmental cues. This circadian rhythm is generated by intrinsic molecular mechanisms in the neurons of the SCN; however, the circadian clock is modulated by a wide variety of influences, including glutamate and pituitary adenylate cyclase-activating peptide (PACAP) from the retinohypothalamic tract, melatonin from the pineal gland, and neuropeptide Y from the intergeniculate leaflet. By virtue of these and other inputs, the SCN responds to environmental cues such as light, social and physical activities. In turn, the SCN controls or influences a wide variety of physiologic and behavioral functions, including attention, endocrine cycles, body temperature, melatonin secretion, and the sleep-wake cycle. Regulation of the sleep-wake cycle by the SCN has important implications for development of therapies for sleep disorders, including those involving desynchronization of circadian rhythms and insomnia.

[Diagnostic value of particularities of circadian rhythms of sleep-wake cycle in early ontogenesis]

According to the data of direct electroencephalography (EEG) human fetus can develop circadian rhythm of sleep-wake cycle before birth. Healthy fetus during birth is awake and takes an active part in the delivery. The fetus sleep during birth is developed only in hypoxic states. EEG irregularities of sleep are noticed yet in fetal stage. Children aged 0-1 year develop five phases of sleep: drowsiness, active sleep, sleep of middle depth, deep sleep, paradoxical REM sleep. Maturity of superficial sleep terminates by the 10th-12th month of life. The sleep of average depth and deep sleep terminate maturity by the 2nd month of life. Duration of paradoxical sleep increases considerably by the age 12th month and is divided into 2 stages. By the age of 12 months paradoxical sleep remains immature. In children of the same age with CNS disorder the structural composition of sleep changes: active sleep is prolonged, sleep of middle depth is not changed, deep sleep does not develop, paradoxical-REM sleep is atypical.

Chronic fatigue, unrefreshing sleep and nocturnal polysomnography

BACKGROUND AND PURPOSE

To investigate the complaint of unrefreshing sleep with study of sleep electroencephalogram (EEG) in patients with chronic fatigue.

PATIENTS AND METHODS

Fourteen successively seen patients (mean age: 41.1 9.8) who complained of chronic fatigue but denied sleepiness and agreed to participate were compared to 14 controls (33.6+/-10.2 years) who were monitored during sleep recorded in parallel. After performing conventional sleep scoring we applied Fast Fourier Transformation (FFT) for the delta 1, delta 2, theta, alpha, sigma 1, sigma 2, beta EEG frequency bands. The presence of non-rapid eye movement (NREM) sleep instability was studied with calculation of cyclic alternating pattern (CAP) rate. Two-way analysis of variance (ANOVA) was performed to analyze FFT results and Mann-Whitney U-test to compare CAP rate in both groups of subjects.

RESULTS

Slow wave sleep (SWS) percentage and sleep efficiency were lower, but there was a significant increase in delta 1 (slow delta) relative power in the chronic fatigue group when compared to normals (P<0.01). All the other frequency bands were proportionally and significantly decreased compared to controls. CAP rate was also significantly greater in subjects with chronic fatigue than in normals (P=0.04). An increase in respiratory effort and nasal flow limitation were noted with chronic fatigue.

CONCLUSIONS

The complaints of chronic fatigue and unrefreshing sleep were associated with an abnormal CAP rate, with increase in slow delta power spectrum, affirming the presence of an abnormal sleep progression and NREM sleep instability. These specific patterns were related to subtle, undiagnosed sleep-disordered breathing.

Sex Differences in Sleep: the Response to Sleep Deprivation and Restraint Stress in Mice

STUDY OBJECTIVES

Numerous clinical studies and sleep surveys have shown pronounced sex differences in the occurrence of insomnia and other sleep pathologies. It has been suggested that sex differences in sleep, while subtle under baseline conditions, may increase in magnitude under biological or environmental challenges. However, controlled and experimental studies on sleep under challenged conditions rarely include female subjects. In this context, we examined sex differences in sleep in the mouse, not only under baseline conditions, but also after sleep deprivation and restraint stress.

DESIGN

Adult male and female C57BL/6J mice were implanted with electrodes to record sleep-wake architecture and sleep electroencephalogram under baseline conditions and after 6 hours of sleep deprivation or 1 hour of restraint stress at the beginning of the daily light phase.

RESULTS

Although baseline sleep patterns slightly differed between the sexes, the homeostatic recovery response to sleep deprivation was similar. In contrast, the changes in sleep after restraint stress were markedly different between male and female mice, with males displaying a stronger initial suppression of sleep and a stronger rebound of rapid-eye-movement sleep later in the recovery phase.

CONCLUSIONS

In mice, the fundamental homeostatic properties of sleep regulation may not differ between the sexes, but the way sleep is affected and disrupted by environmental influences may be sex dependent. The latter may reflect sex differences in stress sensitivity.

Diurnal Sex Differences in the Sleep-Wake Cycle of Mice are Dependent on Gonadal Function

STUDY OBJECTIVES

Sex is an important determinant of the pathophysiology of several disorders that influence and/or impair sleep-wake regulation. To date, few studies have examined either the role of sex or the gonadal hormones on sleep and wakefulness. The difficulty in performing well-controlled clinical experiments on sex and sleep underscores the need for effective animal models to investigate the influence of the gonadal hormones on sleep-wake states. This study describes the influence of sex on sleep and wakefulness in mice, the primary mammalian genetic model for sleep analysis, and tests the hypothesis that gonadal function drives sex differences in sleep-wake states.

DESIGN

Electroencephalogram/electromyogram sleep-wake patterns were recorded in intact and gonadectomized male and female C57BL/6J mice maintained on a 14-hour light:10-hour dark schedule. Following a 24-hour baseline recording, mice were sleep deprived during the light phase by gentle handling and given a 10-hour recovery opportunity during the immediate dark phase.

MEASUREMENTS AND RESULTS

Intact female mice spent more time awake than intact males during 24 hours of baseline recording at the expense of non-rapid eye movement (NREM) sleep. Though the recovery response of NREM sleep was similar between males and females, when examined in reference to baseline levels, females exhibited a more robust recovery response. Gonadectomy in males and females reduced or eliminated the majority of sex differences in sleep architecture and homeostasis.

CONCLUSIONS

These data demonstrate that the gonadal hormones influence the amount, distribution, and intensity of sleep but do not account for all sex differences in the sleep-wake cycle.

P-CPA pretreatment reverses the changes in sleep and behavior following acute immobilization stress rats

The effects of p-CPA (para-chlorophenylalanine) pretreatment was studied on the sleep-wake parameters and patterns of behavioral activities in an animal model of acute immobilization stress. For the experiments, young male Charles Foster rats were divided into three groups, subjected to (i) acute immobilization stress for four hours on specially designed wooden boards, (ii) a similar model of acute immobilization stress after pretreatment of p-CPA (injected through i.p. route), and (iii) control rats (p-CPA untreated and unstressed). Three channels of electrographic signals, i.e., EEG (electroencephalogram), EOG (electrooculogram), and EMG (electromyogram) were recorded continuously for four hours for all three groups of rats to analyze the changes in sleep-wake stages. The assessment of behavior was performed just after the stress on separate groups of rats in Open-Field (OF) and Elevated Plus-Maze (EPM) apparatuses. The significant changes in total sleep time (P < 0.05), total time for rapid eye movement sleep (P < 0.01), and total time in wakefulness (P < 0.01) following acute immobilization stress were found reversed in the p-CPA (a serotonin inhibitor) pretreated group of rats. Simultaneously, the results of the present work also revealed that the changes in grooming behavior (P < 0.05) in OF and the total time spent on the center of EPM (P < 0.05) were observed altered in p-CPA pretreated group of rats.

Using daily 30-min phase advances to achieve a 6-hour advance: circadian rhythm, sleep, and alertness

INTRODUCTION

A ground-based study was undertaken to determine whether circadian and sleep dysfunction could be avoided by "trickling in" a 6-h phase advance in sleep/wake schedule by 12 consecutive 30-min phase advances as per NASA's Appendix K.

METHODS

We simulated a 16-d (384 h) mission for each of 10 subjects. Temporal cues and light levels approximated those experienced in space. All sleep periods were exactly 8 h. Before the study, for 14 d, subjects were required to live on a schedule with a 23:00 bedtime and 07:00 wake time. Laboratory sessions then started with a 4-d baseline segment on that schedule. The fourth night and the day following it were then taken as baseline. Repeated 30-min phase advances in bedtime were then required on each of the next 12 successive nights, resulting in an eventual movement of bedtimes to a 6-h phase-advanced position (bedtime: 17:00, wake time: 01:00). Polysomnographic sleep, circadian rhythms in urinary free cortisol, urinary volume (every void), and core body temperature (once per minute), and ratings of performance, mood, and alertness (five per day) were measured.

RESULTS

While circadian dysfunction was largely avoided by trickling in the phase shift, there remained slight differences in phase between the endogenous circadian pacemaker and the imposed routine which disrupted sleep and daytime alertness.

CONCLUSION

Though statistically significant, the disruption was less than we observed from repeated 2-h phase delays reported in a 2004 ASEM paper. Evidence would thus seem to favor repeated 30-min phase advances over repeated 2-h phase delays.

Sleep, rhythms and women's mood. Part II. Menopause

This review summarizes studies of sleep and other biological rhythms in menopausal women with major depression compared with healthy control subjects. Where feasible, we focused on studies in women who met DSM-IV (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition) criteria for a major depressive episode (MDE) compared with matched normal control subjects and the Staging System for Reproductive Aging in Women (STRAW) criteria. The aim was to review supporting evidence for the hypothesis that a disruption of the normal temporal relationship between sleep and other biological rhythms, such as melatonin, cortisol, thyroid stimulating hormone (TSH) or prolactin, occur during the menopausal transition. As a result, depressive disorders occur in predisposed women. Treatment strategies, designed to correct these altered phase (timing) or amplitude abnormalities, thereby improve mood. Although there may be some common features to menopausal depression compared with other depressive disorders related to the reproductive cycle (e.g. premenstrual dysphoric disorder or postpartum major depression), such as increased morning melatonin secretion, a specific profile of sleep and biological rhythms may distinguish healthy from depressed women during menopause. Further work is needed to characterize more fully the particular abnormalities associated with well-defined menopausal depression in order to develop treatment strategies targeted more specifically to pathogenesis.

Subjective and Objective Measures of Adaptation and Readaptation to Night Work on an Oil Rig in the North Sea

STUDY OBJECTIVES

To study the adaptation and readaptation processes to 1 week of night work (6:30 PM to 6:30 AM) followed by 1 week of day work (6:30 AM to 6:30 PM).

DESIGN

Part of a randomized, placebo-controlled, crossover field study. Here, data from the placebo arm are presented.

SETTING

Oil rig in the North Sea. Work schedule: 2 weeks on a 12-hour shift, with the first week on the night shift and the second week on the day shift.

PARTICIPANTS

Subjects complaining about problems with adjusting to shift work. Seventeen workers completed the study.

INTERVENTIONS

N/A.

MEASUREMENTS

Subjective and objective measures of sleepiness (Karolinska Sleepiness Scale and simple serial reaction time test) and sleep (diary and actigraphy).

RESULTS

Both subjective and objective measures improved gradually during night work. The return to day work after 1 week on the night shift led to a clear increase in subjective sleepiness and worsening of sleep parameters. During the week on the day shift, sleepiness and sleep gradually improved, similar to the improvement seen during night work. The workers indicated that the day shift was worse than the night shift on some of the measures, e.g., sleep length was significantly longer during the night-shift period.

CONCLUSIONS

This is one of few studies showing how shift workers in a real-life setting adjust to night work. Both subjective and objective sleepiness and subjective sleep improved across days. The effects were especially pronounced for the subjective data.

Sleep-wake disturbances in sporadic Creutzfeldt-Jakob disease

BACKGROUND

The prevalence and characteristics of sleep-wake disturbances in sporadic Creutzfeldt-Jakob disease (sCJD) are poorly understood.

METHODS

Seven consecutive patients with definite sCJD underwent a systematic assessment of sleep-wake disturbances, including clinical history, video-polysomnography, and actigraphy. Extent and distribution of neurodegeneration was estimated by brain autopsy in six patients. Western blot analyses enabling classification and quantification of the protease-resistant isoform of the prion protein, PrPSc, in thalamus and occipital cortex was available in four patients.

RESULTS

Sleep-wake symptoms were observed in all patients, and were prominent in four of them. All patients had severe sleep EEG abnormalities with loss of sleep spindles, very low sleep efficiency, and virtual absence of REM sleep. The correlation between different methods to assess sleep-wake functions (history, polysomnography, actigraphy, videography) was generally poor. Brain autopsy revealed prominent changes in cortical areas, but only mild changes in the thalamus. No mutation of the PRNP gene was found.

CONCLUSIONS

This study demonstrates in sporadic Creutzfeldt-Jakob disease, first, the existence of sleep-wake disturbances similar to those reported in fatal familial insomnia in the absence of prominent and isolated thalamic neuronal loss, and second, the need of a multimodal approach for the unambiguous assessment of sleep-wake functions in these patients.

Understanding sleep-wake behavior and sleep disorders in children: the value of a model

PURPOSE OF REVIEW

Sleep-wake problems such as night wakings, excessive crying, or difficulties in falling asleep are frequent behavioral issues during childhood. Maturational changes in sleep and circadian regulation likely contribute to the development and maintenance of such problems. This review highlights the recent research examining bioregulatory sleep mechanisms during development and provides a model for predicting sleep-wake behavior in young humans.

RECENT FINDINGS

Findings demonstrate that circadian and sleep homeostatic processes exhibit maturational changes during the first two decades of life. The developing interaction of both processes may be a key determinant of sleep-wake and crying behavior in infancy. Evidence shows that the dynamics of sleep homeostatic processes slow down in the course of childhood (i.e., sleep pressure accumulates more slowly with increasing age) enabling children to be awake for consolidated periods during the day. Another current topic is the adolescent sleep phase delay, which appears to be driven primarily by maturational changes in sleep homeostatic and circadian processes.

SUMMARY

The two-process model of sleep regulation is a valuable framework for understanding and predicting sleep-wake behavior in young humans. Such knowledge is important for improving anticipatory guidance, parental education, and patient care, as well as for developing appropriate social policies.

Sleep-disordered breathing and blood pressure levels among shift and day workers

BACKGROUND

Sleep-disordered breathing (SDB) can be one of the major determinants of high blood pressure (BP), but there has been no study on SDB with an emphasis on shift workers. The objective of this study was to examine whether a relationship between SDB and blood pressure/hypertension is more evident among shift workers than among day workers.

METHODS

In this cross-sectional study, we measured BP levels and oxygen desaturation index (by nocturnal pulse oximetry) among 253 male shift workers and 206 male day workers aged 30 to 62 years at nuclear power plants in Japan.

RESULTS

The prevalence of SDB (3% oxygen desaturation index >or=10 and >or=15 per hour) in all subjects was 11.3% (95% confidence interval [95% CI] 8.4-14.2) and 6.1% (95% CI 3.9-8.3), respectively, with no statistical difference between shift and day workers. Systolic and diastolic BP levels were correlated with 3% oxygen desaturation index in all subjects after adjustment for potential confounding variables. This association was primarily observed among workers aged >or=40 years, more specifically older shift workers.

CONCLUSIONS

A correlation between SDB severity and diastolic BP levels among shift workers aged >or=40 years suggests the importance of screening for SDB among shift workers for BP control.

[Sleep and circadian rhythms in ageing]

With age, the consolidation of nocturnal sleep decreases, daytime napping increases, and sleep occurs earlier. Sleep regulation is dependent on the interaction between a circadian pacemaker (biological clock) and the sleep homeostat (sleep pressure increasing with duration of time awake). We have shown that in the healthy elderly, the amplitude of circadian rhythms (e. g. melatonin secretion) declines, as does slow wave sleep, parallel with an increase in afternoon sleepiness and a tendency to fall asleep in the early evening when younger subjects do not. Light is the major zeitgeber to stabilise the biological clock: older subjects require sufficient light exposure during daytime and in the evening, and should take no or only brief naps during the day to improve sleep.

Sleep and epilepsy

This article examines the relationship between sleep and epilepsy, an association that has been recognized since antiquity. The mechanisms whereby sleep facilitates seizures are under investigation, although the synchronizing role of thalamocortic networks seems contributory. Recognition of the variety of generalized and partial epileptic syndromes associated with sleep, familiarity with the differential diagnosis of nocturnal spells, and awareness of the role that antiepileptic drugs and sleep disorders may play in epilepsy are helpful in evaluating patients presenting with behavioral and motor disturbances of sleep.

The human circadian system in normal and disordered sleep

The human circadian system regulates rhythmicity in the human body and establishes normal sleep and wake phases. The suprachiasmatic nuclei (SCN), located in the hypothalamus above the optic chiasm, make up the human pacemaker known as the circadian or biological clock, but other essential parts of the circadian system include the pineal gland, retina, and retinohypothalamic tract. The importance of light in resetting the intrinsic human circadian cycle, the intrinsic period of which is slightly longer than 24 hours, ensures that the human cycle will stay entrained to the earth's 24-hour daily cycle. Within the SCN neurons, circadian rhythmicity is generated by the regular transcription of proteins. Since the circadian system is the foundation of the sleep-wake cycle, disorders and abnormalities in sleep are often connected with disorders or abnormalities in the circadian system. Circadian rhythm sleep disorders, such as jet lag syndrome and shift work sleep disorder, are those specifically attributed to dysfunctions or insufficiencies in the circadian system. Taking into consideration the preeminence of the circadian clock in timing sleep, it is likely that other sleep disorders, such as insomnia, are also linked to circadian system abnormalities.