Point and interval estimations of circadian melatonin ecphasia in Smith-Magenis syndrome

An inferential statistical quantification of chronomes (time structures) in the range of everyday physiology has earlier revealed changes affecting the circadian amplitude of melatonin in the absence of changes in the chronome-adjusted mean value (MESOR) or in the acrophase. A chrono-meta-analysis of published data on patients with the Smith-Magenis syndrome herein quantifies the average extent of shift in the acrophase of the circadian melatonin rhythm, reported earlier by others time-macroscopically as an antiphase. Time-microscopically, the phase shift averages 9.6 +/- 0.9 h. Circadian melatonin ecphasia complements blood pressure ecphasia in non-insulin-dependent diabetes mellitus, associated with autonomic dysfunction. The shift in phase of the peak melatonin secretion from the night into the day, associated with specific genetic findings, raises basic questions concerning the designation of melatonin as a hormone associated with darkness. Whether a resetting of the circadian acrophase beyond providing melatonin for sleep improvement can provide benefit remains to be investigated.

Increased plasma homocysteine levels in shift working bus drivers

BACKGROUND

Previous studies have indicated an association between shift work and cardiovascular disease. There is also considerable epidemiological evidence that hyperhomocysteinemia is an independent risk factor for cardiovascular disorders.

AIMS

To analyse plasma homocysteine levels in shift work bus drivers, and to investigate possible relations with sleep parameters and other biochemical factors.

METHODS

Blood samples were collected from 30 male shift working long-haul bus drivers in a Brazilian sample and analysed for plasma levels of homocysteine, folic acid, vitamin B(12), and serum lipids. A group of 22 daytime workers, matched for age and body mass index served as controls. The incidence of mutations in the gene coding for methylene tetrahydrofolate, an enzyme which is related to hyperhomocysteinemia, was also assessed. Polysomnographic recordings were obtained from the target group.

RESULTS

Bus drivers showed significantly higher levels of plasma homocysteine than the control group (18.57 v 9.43 micro M). Most of the other biochemical, behavioural, and molecular parameters did not differ between groups. Likewise, sleep parameters appeared to be within the normal range.

CONCLUSIONS

The significantly increased plasma homocysteine levels in long-haul bus drivers did not appear to be secondary to other biochemical or behavioural problems in this group. These results suggest that hyperhomocysteinemia may be involved in the increased incidence of cardiovascular diseases observed in shift workers.

Underlying sleep pathology may cause chronic high fatigue in shift-workers

About 20-25% of the population in primary healthcare settings complains of chronic fatigue but this symptom has been under-emphasized compared with sleepiness in clinical practice. Shift-workers are particularly vulnerable because of various fatigue-related personal and public morbidity and mortality. The goal of this cross-sectional study was to explore if fatigue severity could be used as an independent predictive tool to identify underlying sleep pathology. The 21 most-fatigued (study group) and 23 least-fatigued (control) miners were selected on the basis of the Fatigue Severity Scale (FSS), which was administered to 195 subjects in an underground mine in Timmins, a town in northern Ontario. The two groups were matched for age, gender, and body mass index (BMI). Mean FSS score for the most-fatigued subjects was 4.9 +/- 0.5 and the least-fatigued was 2.2 +/- 0.5 (P < 0.0001). The subjects from each group were studied polysomnographically to identify sleep disorders. The polysomnographic data in 15 of 21 (71.4%) of the most-fatigued subjects displayed significant sleep pathology compared with only three of 23 (13.0%) in the least-fatigued subjects. Based on Fisher's exact test, the difference between the two groups was highly significant (P < 0.0001). Also, in the total subject pool (n = 195), the correlation between subjective fatigue and sleepiness was not very strong (Pearson's r = 0.45), suggesting that these two symptoms can be independent phenomena. It is concluded that chronic high fatigue can be an independent manifestation of underlying sleep pathology, which warrants independent subjective and objective assessment.

Sleep-wake rhythm in an irregular shift system

Sleep in shift work has been studied extensively in regular shift systems but to a lesser degree in irregular shifts. Our main aim was to examine the sleep-wake rhythm in shift combinations ending with the night or the morning shift in two irregular shift systems. Three weeks' sleep/work shift diary data, collected from 126 randomly selected train drivers and 104 traffic controllers, were used in statistical analyses including a linear mixed model and a generalized linear model for repeated measurements. The results showed that the sleep-wake rhythm was significantly affected by the shift combinations. The main sleep period before the first night shift shortened by about 2 h when the morning shift immediately preceded the night shift as compared with the combination containing at least 36 h of free time before the night shift (reference combination). The main sleep period before the night shift was most curtailed between two night shifts, on average by 2.9 and 3.5 h among the drivers and the controllers, respectively, as compared with the reference combination. Afternoon napping increased when the morning or the day shift immediately preceded the night shift, the odds being 4.35-4.84 in comparison with the reference combination. The main sleep period before the morning shift became 0.5 h shorter when the evening shift preceded the morning shift in comparison with the sleep period after a free day. The risk for dozing off during the shift was associated only with the shift length, increasing by 17 and 35% for each working hour in the morning and the night shift, respectively. The results demonstrate advantageous and disadvantageous shift combinations in relation to sleep and make it possible to improve the ergonomy of irregular shift systems.

Gender differences in excessive daytime sleepiness among Japanese workers

Excessive daytime sleepiness (EDS) is serious concern in the workplace with respect to errors, accidents, absenteeism, reduced productivity and impaired personal or professional life. Previous community studies found a female preponderance of EDS, however, there is little research on EDS and gender in occupational settings. We examined the gender differences in prevalence and risk factors of EDS among employees working at a telecommunications company in the Tokyo metropolitan area. Our outcome measure of EDS was the Epworth Sleepiness Scale (ESS). A self-administered questionnaire on health and sleep including ESS was distributed to 5,571 workers between December 1999 and January 2000, and 5,072 responses were returned (91.0%). A total of 4,722 full-time, non-manual and non-shift employees aged 20-59 were used for analysis (3,909 men and 813 women). Chi-squared tests and multiple logistic regression analyses were applied for examining the gender differences in the prevalence and risk factors of EDS. The prevalence rates of EDS were 13.3% for women and 7.2% for men (P<0.001). We identified that deprived nocturnal sleep, an irregular sleep-wake schedule and depression were the risk factors of EDS for both genders, and being married worked as a protective factor against EDS for men alone. It is obvious that a ban on overtime work and a provision of mental health hygiene are the general strategies for reducing EDS at worksites. In the case of women, we suggest the formation of effective strategies for improving women's status at home and in the workplace must also be a solution for the prevention of EDS (e.g. promoting gender equality in the division of labor at home and strengthening family care policies for working women).

Sleep patterns of children with pervasive developmental disorders

Data on sleep behavior were gathered on 100 children with pervasive developmental disorders (PDD), ages 2-11 years, using sleep diaries, the Children's Sleep Habits Questionnaire (CSHQ), and the Parenting Events Questionnaire. Two time periods were sampled to assess short-term stability of sleep-wake patterns. Before data collection, slightly more than half of the parents, when queried, reported a sleep problem in their child. Subsequent diary and CSHQ reports confirmed more fragmented sleep in those children who were described by their parents as having a sleep problem compared to those without a designated problem. Interestingly, regardless of parental perception of problematic sleep, all children with PDD exhibited longer sleep onset times and greater fragmentation of sleep than that reported for age-matched community norms. The results demonstrate that sleep problems identified by the parent, as well as fragmentation of sleep patterns obtained from sleep diary and CSHQ data, exist in a significant proportion of children with PDD.

Sleepiness and sleep disorders in shift workers: a study on a group of italian police officers

STUDY OBJECTIVES

evaluation of shift-work effect on sleepiness, sleep disorders, and sleep-related accidents in a population of police officers.

DESIGN

Aquestionnaire-based survey was used to gather information on age and physical characteristics, working conditions, sleep problems, and accidents. Sleepiness was measured by the Epworth Sleepiness Scale (ESS) while the presence of sleep disorders was evaluated by a score (SDS) drawn from indicators of insomnia, breathing disorders, periodic limb movements and restless legs syndrome, and hypersomnia. The effects of age, gender, body mass index, working conditions, and seniority on ESS, SD score, and accidents were analyzed by linear and logistic regression.

SETTING

The self-administered questionnaires were filled in by police officers in the district of Genoa (Italy).

PARTICIPANTS

1,280 police officers: 611 shift workers (SW) and 669 non-shift workers (NSW).

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

The ESS score was not higher in SW than in NSW, while the SDS was significantly influenced by shift-work conditions and seniority in shift work. The occurrence of sleep-ascribed accidents was significantly increased in the SW group and related to the presence of indicators of sleep disorders. There was evidence for sleep disorders in 35.7% of SW and in 26.3% of NSW.

CONCLUSIONS

Shift-work conditions and seniority may enhance sleep disorders and may favor sleep-related accidents, but they do not influence ESS score. Stressful conditions could cause sleepiness to be underestimated, or else they might overcome sleepiness. However, our data should alert occupational health physicians for the diagnosis and prevention of possible undetected intrinsic sleep disorders, which could possibly worsen shift workers' health and increase the risk of accidents.

The impact of a nap opportunity during the night shift on the performance and alertness of 12-h shift workers

The purpose of this workplace evaluation was to assess the effects on performance, alertness and subsequent sleep of strategic napping on 12-h overnight shifts. In a counterbalanced crossover design, 24 male aircraft maintenance engineers working in a forward rotating 12-h shift pattern volunteered to take part in the study for two work weeks. During the experimental week, each subject was given the opportunity to take a 20-min nap at work between 01:00 and 03:00 h on each of their two overnight shifts. On the control week no naps were taken on the night shifts. A computerized neurobehavioural test battery was employed to assess performance and subjective levels of fatigue at the beginning and end of each night shift, and pre- and postnap. Subjects were also asked to rate how near they had come to falling asleep while driving to and from work. The results revealed that taking a single 20-min nap during the first night shift significantly improved speed of response on a vigilance task measured at the end of the shift compared with the control condition. On the second night shift there was no effect of the nap on performance. Taking a short nap during either night shift had no significant effect on subjective ratings of fatigue, the level of sleepiness reported while driving to and from work, or subsequent sleep duration and sleep quality. Overall the results suggest some promise for a short duration nap taken in the workplace to counteract performance deficits associated with the first night shift.

Circadian preference, sleep and daytime behaviour in adolescence

The aim of this study was to determine the relationship between circadian preferences, regularity of sleep patterns, sleep problems, daytime sleepiness and daytime behaviour. As a part of an epidemiological survey on sleep in a representative sample of Italian high-school students, a total of 6631 adolescents, aged 14.1-18.6 years, completed the School Sleep Habits Survey, a comprehensive questionnaire including items regarding sleep, sleepiness, substance use, anxiety and depressed mood, use of sleeping pills, school attendance and a morningness/eveningness scale. The sample consisted of 742 evening-types (315 males and 427 females; mean age 17.1 years) and 1005 morning-types (451 males and 554 females; mean age 16.8 years). No significant sex differences were found for morningness/eveningness score. Eveningness was associated with later bedtime and wake-up time, especially on weekends, shorter time in bed during the week, longer weekend time in bed, irregular sleep-wake schedule, subjective poor sleep. Moreover, evening types used to nap more frequently during school days, complained of daytime sleepiness, referred more attention problems, poor school achievement, more injuries and were more emotionally upset than the other chronotype. They referred also greater caffeine-containing beverages and substances to promote sleep consumption. Our results suggest that circadian preference might be related not only to sleep pattern, but also to other adolescent behaviours.

[Sleep disorders and mental disorders]

BACKGROUND

Recent research has revealed a lot of the secrets of sleep and how sleep influences our daily life and mental functioning.

MATERIAL AND METHODS

Current knowledge on the interaction between sleep disturbances and mental disorders is reviewed. The review is based on relevant literature identified by search in Medline and PsycInfo.

RESULTS

Research shows that sleep as a psychobiological phenomenon interacts with the processes of mental disorders. The best evidence for interactions between sleep disturbances and mental problems is found in depression, and sleep disturbances over some weeks have been found to be a predictor for depressive disorders.

INTERPRETATION

Clinicians must distinguish between primary chronic sleep disorders of functional origin and secondary sleep disorders as part of a psychiatric condition. The former category should be treated by non-pharmacological interventions, while the latter should be adequately treated in a biopsychosocial model.

Shift work and health

OBJECTIVES

This article describes the characteristics of shift workers and compares stress factors and health behaviours of shift and regular daytime workers. Based on an analysis of people followed over four years, associations between the incidence of chronic conditions and changes in psychological distress levels are explored in relation to working shift.

DATA SOURCES

Data are from the 2000/01 Canadian Community Health Survey, the longitudinal (1994/95, 1996/97 and 1998/99) and cross-sectional (1994/95) components of the National Population Health Survey, and the Survey of Work Arrangements (1991 and 1995).

ANALYTICAL TECHNIQUES

Cross-tabulations were used to profile shift workers and to compare some of their health behaviours and sources of stress with those of regular daytime workers. Multivariate analyses were used to examine associations between shift work and the incidence of chronic conditions and changes in psychological distress levels over four years, controlling for other potential confounders.

MAIN RESULTS

Men who worked an evening, rotating or irregular shift had increased odds of reporting having been diagnosed with a chronic condition over a four-year period. For both sexes, an evening shift was associated with increases in psychological distress levels over two years.

Diurnal variation in daytime sleepiness of patients with sleep apnea syndrome

Diurnal variations in daytime sleepiness were studied in 26 men with sleep apnea syndrome (SAS) [age, 41.7 +/- 9.9 years (mean +/- SD); body mass index, 30.0 +/- 6.2 kg/m2; Epworth Sleepiness Score, 8.7 +/- 4.1; apnea-hypopnea index, 50.2 +/- 22.0]. Sleep latencies measured at 09.00 h, 11.00 h, 13.00 h, 15.00 h, and 17.00 h were 3.4 +/- 3.6 min, 4.7 +/- 5.5 min, 5.2 +/- 4.4 min, 5.3 +/- 5.4 min, and 9.3 +/- 7.2 min, respectively (ANOVA, P < 0.05). Daytime sleepiness in patients with SAS was more pronounced in the morning than in the afternoon and evening.

[Melatonin treatment of a blind child with serious sleep disorders]

BACKGROUND

Children with developmental and neurological disabilities are prone to develop serious sleep-wake cycle disorders that may be difficult to treat.

MATERIAL AND METHODS

Case history.

RESULTS

A 5-year old blind boy with multiple disabilities developed a chronic sleep-wake cycle disorder as his main clinical problem. Treatment included introduction of strict sleep habits and strengthening of environmental "zeitgebers". After five months melatonin 3 mg was administered at night for 4 weeks. The observation period also included 3 weeks without melatonin. Sleep was registered prospectively by a sleep diary. Strict sleep habits combined with strengthening of "zeitgebers" partially improved the sleep problems, but did not establish a normal sleep pattern. When melatonin was added, he normalized his sleep pattern in a few days. His sleep problems returned during the weeks in which he did not receive melatonin. No side effects were observed.

INTERPRETATION

Melatonin is a promising treatment alternative for serious sleep problems in blind children.

Effect of light treatment on sleep and circadian rhythms in demented nursing home patients

OBJECTIVES

To determine whether fragmented sleep in nursing home patients would improve with increased exposure to bright light.

DESIGN

Randomized controlled trial.

SETTING

Two San Diego-area nursing homes.

PARTICIPANTS

Seventy-seven (58 women, 19 men) nursing home residents participated. Mean age +/- standard deviation was 85.7 +/- 7.3 (range 60-100) and mean Mini-Mental State Examination was 12.8 +/- 8.8 (range 0-30).

INTERVENTIONS

Participants were assigned to one of four treatments: evening bright light, morning bright light, daytime sleep restriction, or evening dim red light.

MEASUREMENTS

Improvement in nighttime sleep quality, daytime alertness, and circadian activity rhythm parameters.

RESULTS

There were no improvements in nighttime sleep or daytime alertness in any of the treatment groups. Morning bright light delayed the peak of the activity rhythm (acrophase) and increased the mean activity level (mesor). In addition, subjects in the morning bright light group had improved activity rhythmicity during the 10 days of treatment.

CONCLUSION

Increasing exposure to morning bright light delayed the acrophase of the activity rhythm and made the circadian rhythm more robust. These changes have the potential to be clinically beneficial because it may be easier to provide nursing care to patients whose circadian activity patterns are more socially acceptable.

Factors related to the occurrence of isolated sleep paralysis elicited during a multi-phasic sleep-wake schedule

STUDY OBJECTIVES

To further investigate mechanisms of isolated sleep paralysis (ISP) in normal individuals, we experimentally elicited ISPs by facilitating sleep onset REM periods (SOREMP), a prerequisite of ISPs, and examined behavioral and psychological measurements relating to ISP appearances.

DESIGN

The multi-phasic sleep/wake schedule (MPS) began at approximately midnight and ended when net sleep reached 7.5 hours. Participants were awakened after every 5 min of REM sleep to obtain a maximum number of SOREMPs. Upon each awakening, mentation reports and subjective measurements were collected. Performance tests were then assigned.

SETTING

Sleep lab, Tokyo Metropolitan Institute for Neurosciences, Japan.

PARTICIPANTS

Thirteen healthy Japanese students (10 males) with high self-reported frequencies of ISPs but no other narcolepsy-related symptoms.

INTERVENTIONS

MEASUREMENTS AND RESULTS

From 184 sleep interruptions, 8 ISP episodes were obtained. In within participant comparisons between episodes with and without ISPs, the vigilance task (VT) reaction times were elevated before SOREMPs with ISPs. In between analyses (ISP vs non-ISP), the ISP group showed poorer performance, more complaints of physical, mental, and neurotic symptoms, increased subjective fatigue and increased stage 1 throughout the entire schedule. VT hit rates remained constant in the non-ISP group, but dropped in the later part of schedule in the ISP group. Subjective sleepiness dropped over time in the non-ISP group while it slightly increased in the ISP group.

CONCLUSIONS

ISP is likely to appear as a phenotype of REM dissociation during SOREMP when participants with low tolerance for disrupted sleep-wake rhythms are placed in this type of schedule.

Daytime sleepiness and cognitive impairment in the elderly population

BACKGROUND

Recent findings suggest that there may be a relationship between excessive daytime sleepiness (EDS) and cognitive deficits. This study aims to determine to what extent EDS is predictive of cognitive impairment in an elderly population.

METHODS

A total of 1026 individuals 60 years or older representative of the general population living in the metropolitan area of Paris, France, were interviewed by telephone using the Sleep-EVAL expert system. To find these individuals, 7010 randomly selected households were called: 1269 had at least 1 household member in this age range (participation rate, 80.9%). In addition to Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, and International Classification of Sleep Disorders diagnoses, the system administered to participants the Psychological General Well-being Schedule, the Cognitive Difficulties Scale (MacNair-R), and an independent living scale.

RESULTS

Excessive daytime sleepiness was reported by 13.6% of the sample, with no significant difference among age groups. Compared with nonsleepy participants, those with EDS were at increased risk of cognitive impairment on all the dimensions of the MacNair-R scale after controlling for age, sex, physical activity, occupation, organic diseases, use of sleep or anxiety medication, sleep duration, and psychological well-being. The odd ratios were 2.1 for attention-concentration deficits, 1.7 for praxis, 2.0 for delayed recall, 2.5 for difficulties in orientation for persons, 2.2 for difficulties in temporal orientation, and 1.8 for prospective memory.

CONCLUSIONS

Among elderly individuals in the general population, EDS is an important risk factor for cognitive impairment. A complaint of EDS by an elderly patient should signal the possibility of an underlying cognitive impairment in need of evaluation.

Rapid cycling bipolar disease: new concepts and treatments

Having been recognized by Kraeplin at the beginning of the 20th century, rapid cycling was first described as a specific entity by Dunner et al. in 1974. The prevalence of rapid cycling ranges from 12% to 20% in patients with bipolar disorder who are not selected for a high rate of cycling.

Neurological impairments and sleep-wake behaviour among the mentally retarded

The objective of the present study was to evaluate the relationship between the sleep-wake behaviour and neurological impairments among mentally retarded people. The sleep-wake behaviour of 293 mentally retarded subjects living in a rehabilitation center was studied by a standardized observation protocol carried out by trained staff members. The protocol consisted of brief check-ups of the subjects' sleep-wake status at 20-min intervals for five randomly chosen 24-h periods during 4 months. From the raw data five sleep-wake behaviour variables were formed. The data concerning the subject characteristics (age, body mass index (BMI), gender, degree of mental retardation, presence of locomotor disability, that of epilepsy, blindness or deafness and the usage of psychotropic medications) were collected from the medical records. Two main findings emerged: (1) severe locomotor disability, blindness and active epilepsy were found to be independent predictors of increased daytime sleep and increased number of wake-sleep transitions and (2) the subjects with a combination of two or all three of these impairments had a significantly more fragmented and abnormally distributed sleep than those with none or milder forms of these impairments. Age, BMI, degree of mental retardation and the studied medications played a minor role in the sleep disturbances of the study population. Finally, deafness was not found to be associated with any of the measured sleep-wake variables.

Sleep phase advance and lithium to sustain the antidepressant effect of total sleep deprivation in bipolar depression: new findings supporting the internal coincidence model?

Recent European studies suggested that sleep phase advance (SPA) could sustain the effects of total sleep deprivation (TSD) both with or without a combined antidepressant drug treatment. Previous studies by our group showed that an ongoing lithium treatment could enhance and sustain the effect of repeated TSD. In the present study we studied the effect of a single TSD followed by 3 days SPA (beginning with sleep allowed from 17:00 until 24:00, with daily shiftbacks of 2 h) in consecutively admitted bipolar depressed inpatients who were taking a chronic lithium salts treatment (n=16) or who were devoid of psychotropic medications (n=14). Changes in mood during treatment were recorded with self administered visual analogue scales and with Hamilton rating scale for depression. Results showed that SPA could sustain the acute antidepressant effect of TSD, and that lithium enhanced the effect of the chronobiological treatment. According to the internal coincidence model, the better clinical effects observed in lithium-treated patients could be due to the phase delaying effect of lithium on biological rhythms, leading to a better synchronization of biological rhythms with the sleep-wake cycle.

[Drowsiness--greater traffic hazard than alcohol. Causes, risks and treatment]

Stress and shortage of sleep may cause daytime somnolence and impaired vigilance at the wheel, especially among those suffering from sleep disturbances. According to the international consensus meeting in Stockholm in May of 2000 on "The sleepy driver and pilot--causes, risks and countermeasures", drowsy driving is an underestimated risk factor in official statistics, and as many as 15-30 percent of today's traffic accidents are related to drowsiness; thus it is an even greater risk factor than alcohol. Drowsy drivers suffer from inattention, impaired concentration and may even fall asleep at the wheel. Accidents during dozing result in three times as many fatalities as other accidents. There are a number of reasons for habitual drowsiness at the wheel aside from sleep deprivation, including rhonchopathy, shift work and jet lag, mental depression, insomnia, narcolepsy, endocrinological diseases, periodic limb movement disorder, medication, pain-disordered sleep, and heart disease. Among the most active drivers, i.e. middle aged men, obstructive sleep apnea syndrome (OSAS) has been found to be the most common reason for habitually drowsy driving. OSAS causes a 2-3 fold increased risk of traffic accidents, and it impairs simulated driving. Palatoplasty as well as nasal CPAP have been shown to improve vigilance and driving performance to an extent that the increase in risk is eliminated. Drivers suffering from habitual drowsiness and micro-sleep attacks forcing them to take repeated rests are at special risk. Even if they are as dangerous as drivers with unlawful blood alcohol levels they cannot be caught in a police checkpoint. However they often seek medial advice, and properly treated they may often return safely to traffic. If not, there could be a need to report them to the authorities so as to limit or prohibit their driving.

[International consensus meeting on fatigue and the risk of traffic accidents. The significance of fatigue for transportation safety is underestimated]

Recently there has been a sizeable increase in research on fatigue and accidents in transportation. Therefore a meeting was convened last year to discuss prevalence, mechanisms and countermeasures, with the intention to produce an international consensus document. It was concluded that official statistics strongly underestimate prevalence, and that a reasonable estimate, based on research, lies between 10 and 20% for accidents on the road, in the air and at sea. The main causes are disturbed sleep and work at the circadian low, caused by night work, morning work, sleep/wake disorders (including sleep apnea) or social obstacles to sleep. Suggested countermeasures include information/education of the public and of transportation companies, as well as enforcement of existing work hour regulation. Additional countermeasures include strategic use of napping and caffeine, as well as implementation of rumble strips and--possibly--electronic devices for drowsiness detection.

Effects of vitamin B12 on bright light on cognitive and sleep-wake rhythm in Alzheimer-type dementia

The present study investigated the effects of vitamin B12 (VB12) on circadian rhythm in Alzheimer-type dementia (ATD). Twenty-eight ATD patients were treated with bright light therapy (BLT) for 8 weeks. For the latter 4 weeks, half were treated with VB12 with BLT (BLT + VB12). We evaluated the cognitive state with Mini-Mental State Examination and the circadian rhythm with actigraphy after the fourth and eighth week. After the first 4 weeks BLT improved the circadian rhythm disturbances and cognitive state especially in the early stage of ATD. Although the latter 4 week-BLT caused no significant effects on the circadian rhythm; BLT + VB12 improved the vigilance level during the daytime. These results suggest that VB12 has some efficiency to enhance vigilance for ATD patients.

A quantitative model of work-related fatigue: background and definition

Fatigue has been identified as a major risk factor for shiftworkers. However, few organizations or governments currently manage work-related fatigue in any systematic or quantitative manner. This paper outlines an approach to managing fatigue that could improve shiftwork management. Using shift start and finish times as an input, the outlined model quantifies work-related fatigue on the basis of its known determinants; that is shift timing and duration, work history and the biological limits on sleep length at specific times of day. Evaluations suggest that work-related fatigue scores correlate very highly with sleep-onset latency, neurobehavioural impairment and subjective sleepiness. The model is useful in that it allows comparisons to be made between rosters independent of shift length and timing or the total number of work hours. Furthermore, unlike many models of sleepiness and fatigue, individual's sleep times are not required as hours of work are used as the input. It is believed the model provides the potential quantitatively to link the effects of shiftwork to specific organizational health and safety outcomes. This simple approach may be especially critical at a time when many organizations view longer and more flexible hours from their employees as an immediate productivity gain.

["Reading-your-baby lessons" for parents of excessively crying infants--the concept of "guided parent-infant training sessions"]

New findings indicate that persistent crying (infantile "colic") may be closely interlinked with regulatory difficulties in the organization of sleep and waking states and in sustaining prolonged episodes of uninterrupted sleep. It has been shown that preverbal communication plays a significant role in the regulation of infant states and in the prevention of infantile persistent crying. However, parents are usually unaware of these explanations, and tend to attribute the crying to inappropriate causes or have no understanding at all about why their child cries so much. Therefore, the baby's signals are not answered in an effective way. In this article "guided parent-infant-training sessions", a new treatment method for parents with excessively crying babies, will be introduced. It is the goal of this approach to help parents to improve the "reading" of their child's signals and to act according to the baby's needs. In order to provide an opportunity for training, parents are given their appointment at a time, when it is most likely for the child to cry. In the context of a therapeutic relationship they may be experiencing for the first time calming a baby they previously thought to be inconsolable.

[Assessment of excessive day-time sleepiness in professional drivers with suspected obstructive sleep apnea syndrome]

Excessive daytime sleepiness is a common symptom of obstructive sleep apnea syndrome (OSAS) and can be a cause of traffic accidents, creating a problem of particular importance for professional drivers given the associated death, disability and professional repercussions. We assessed whether the Epworth sleepiness scale (ESS), which is a subjective measure of daytime sleepiness, correlates well with multiple sleep latency (MSL) testing, which gives an objective measure of daytime sleepiness. We also compared each method with the results of polysomnography (apnea-hypopnea index, arousal index and minimum oxygen saturation). We studied 55 professional drivers suspected of OSAS. All answered the ESS questionnaire and underwent polysomnographic and MSL testing. We found a significant, though not relevant, correlation between the degree of excessive daytime sleepiness estimated by the ESS and by MSL testing (r = -0.41; p = 0.002). A significant, though weak, correlation was found between the ESS score and the arousal index (r = 0.26; p < 0.05). Our results do not clarify which method is best for measuring excessive daytime sleepiness in professional drivers suspected of OSAS.

Instability of sleep patterns in children with attention-deficit/hyperactivity disorder

OBJECTIVE

To compare the stability of the sleep-wake system of children with attention-deficit/hyperactivity disorder (ADHD) and controls by objective and subjective measures.

METHOD

Thirty-eight school-age boys with diagnosed ADHD and 64 control school-age boys were examined using actigraphic monitoring and sleep diaries, over 5 consecutive nights.

RESULTS

Increased instability in sleep onset, sleep duration, and true sleep were found in the ADHD group compared with the control group. Discriminant analysis revealed that children's classification (ADHD versus control) could be significantly predicted on the basis of their sleep measures.

CONCLUSIONS

The findings support the hypothesis that instability of the sleep-wake system is a characteristic of children with ADHD. Given the potential negative effects of disturbed or unstable sleep on daytime functioning, it is recommended that a thorough sleep assessment be conducted when a sleep disturbance is suspected or when symptoms associated with daytime sleepiness or decreased arousal level are present.

Long-term effects of CPAP on daytime functioning in patients with sleep apnoea syndrome

Daytime sleepiness, impaired cognitive performance and dysphoric mood are often present in patients with obstructive sleep apnoea syndrome (SAS). This prospective controlled study evaluates the effects of treatment with continuous positive airway pressure (CPAP) during 1 yr on daytime functioning in a large group of patients with SAS. The authors studied 80 patients (mean+/-sem 49+/-1 yrs) with SAS with a mean apnoea-hypopnoea index of 60+/-2 h-1, and 80 healthy control subjects matched for sex and age (46+/-1 yrs.). Measurements were obtained at the beginning of the study and 12+/-1 months later, and included: daytime sleepiness (Epworth scale), depression and anxiety (Beck tests), vigilance (Steer-Clear) and reaction time (Psychometer Vigilance Test 192). Drug, coffee and alcohol intake, as well as the sleep schedule, were also recorded. Results showed that, before treatment, patients were more somnolent (p<0.001), anxious (p<0.01) and depressed (p<0.001) than control subjects. Also, they had a longer reaction time (p<0.05) and poorer vigilance (p<0.01). The use of CPAP improved significantly the levels of somnolence (p<0.0001) and vigilance (p<0.01), but failed to modify anxiety and depression. Reaction time changes were minor. Variables with a potential confounding effect did not change during the study. These results provide firm evidence to substantiate the use of continuous positive airway pressure in patients with sleep apnoea syndrome.

[Shift work, social class and ischemic heart disease in middle-aged and elderly men. A 22-year follow-up in the "Copenhagen Male Study"]

Shift work has been reported as a risk factor for ischaemic heart disease. Most studies have only partly controlled for social class differences, a recognized risk factor for ischaemic heart disease (IHD), and the relative risk of 1.4 could be a result of confounding. The Copenhagen Male Study was established in 1971 as a prospective cohort study of 5,249 men, and included questions on working time, social class and other potential confounders. The cohort was followed through registers for 22 years. Risk of IHD and all cause mortality did not differ between shift and day workers, the adjusted relative risk for IHD being 0.9 (0.7-1.1). Restriction to social class III led to lower risk estimates, with an adjusted relative risk of 0.7 (0.5-1.0). The study gave no support to the hypothesis that shift work is an independent risk factor for IHD. The role of shift work as an independent risk factor for IHD is still controversial.