Work at sea: a study of sleep,and of circadian rhythms in physiological and psychological functions,in watchkeepers on merchant vessels

Performance scores on both a simple detection task and a complex visual judgment task, together with subjective alertness ratings, were collected 4-hourly from 19 watchkeepers working a "4-on/8-off" routine, and from 20 dayworkers, over consecutive days of voyages on merchant ships. Adaptation of the circadian rhythms in the measures to the shifted hours of work of the three sections of the watchkeeping crews was at best only partial. These rhythms resulted in a depression of the levels of most measures during the night hours, which was exacerbated by the effects of recent awakening from sleep. It is suggested that these unwanted variations in operational effectiveness could be largely removed by replacing the 4-on/8-off watchkeeping system, with its associated "split" sleep pattern, by one which allows a single full length sleep each day. Such a system would encourage better adaptation of the rhythms; effects of recent awakening could be avoided by the provision of an adequate "waking up" period before duty begins.     

Work at sea: a study of sleep,and of circadian rhythms in physiological and psychological functions,in watchkeepers on merchant vessels

Summary Sleep length and sleep quality scores were collected on board ships over periods of up to two weeks from 38 watchkeepers working a 4-on/8-off routine and 29 dayworkers. All watchkeepers exhibited fragmented sleeping patterns, which indicated a lack of adaptation of the sleep/wakefulness cycle to the hours of work. There were only slight differences in total sleep length between watchkeepers and dayworkers, however, both groups did not obtain an adequate amount of sleep. Within the watchkeeping crews the 3rd Officers had by far the shortest sleep length. Concerning sleep quality, daytime sleep was generally given the lowest ratings, whereas sleep starting before midnight was on average evaluated as the best, both by watchkeepers and dayworkers. Watchkeeping personnel do not normally have any days off during a voyage so that missed sleep might even amount to a sleep deficit. A solution for this problem could perhaps be a new, stabilized system that allows a single uninterrupted sleep, which is required for full recuperation, to be taken each day.Dedicated to Professor J. Aschoff on the occasion of his 75th birthdayPartly supported by a grant from the Ministry for Technology and Research, Federal Republic of Germany, Project Schiff der Zukunft, Part ET83b     

Work at sea: a study of sleep,and of circadian rhythms in physiological and psychological functions,in watchkeepers on merchant vessels

Summary Oral and rectal temperature, urinary excretion of adrenaline and noradrenaline, and heart rate were measured in 28 watchkeepers working a 4-on/8-off routine, and in 25 dayworkers, on board ships. Readings of oral temperature were taken over 4-hourly periods of up to two weeks; the rectal temperature, urine, and heart rate data were collected on selected days within these periods. Analysis of watchkeepers' temperatures and unconjugated catecholamine excretions showed slight signs of an interactive adaptation to time of day and hours of work, but it was clear that full phase adjustment of the circadian rhythms to shifted hours of work did not occur. The split pattern of sleep imposed by the watch system may be a major factor in preventing complete adaptation of physiological rhythms to shift work in the shipboard situation; this problem could be overcome by devising a system that allows sleep to be taken in a single uninterrupted block each day.We kindly acknowledge financial support by the Deutsche Forschungsgemeinschaft     

Work at sea: a study of sleep,and of circadian rhythms in physiological and psychological functions,in watchkeepers on merchant vessels

The safety of a ship depends substantially on its bridge watchkeepers, whose alertness and efficiency must be maintained at all hours of the day and night. Fatigue, circadian rhythms, and sleep disruption occasioned by the unusual working hours of these personnel may all affect their performance. A methodology for assessing the magnitude of this problem is proposed. The application of this methodology in a large-scale shipboard study of merchant mariners on extended voyages is then described, and details given of the techniques used to measure sleep and activity, and temporal variations in a range of physiological und psychological parameters. A summary of the data collected in the study is provided as a reference point for the reports on the different aspects of the results that follow in subsequent articles.     

Changes in the temperature rhythm of submariners following a rapidly rotating watchkeeping system for a prolonged period

Summary On-watch readings of oral temperature were obtained at hourly intervals from submariners during two continuously submerged voyages of 48 days duration. The subjects followed a rapidly rotating watchkeeping system of 4-h dutyspells during the entire period. In the majority of cases, the amplitude of the circadian temperature rhythm progressively declined, and this was accompanied by a tendency for the rhythm to disintegrate into shorter periods, associated with the length of the duty spell and the particular pattern of sleep adopted. On one voyage, one subject's rhythm showed a tendency to free-run, with a period of 24.6 h. It is concluded that the results give pointers to the kind of effect to be looked for in studies of shift-workers following similarly highly irregular patterns of work.     

Relationship between subjective and actigraphy-measured sleep in 237 patients with metastatic colorectal cancer

Objective

Patients with cancers frequently experience sleep and circadian dysfunction. To date, only a few studies have used both a questionnaire and actigraphy for concomitant evaluation of sleep and circadian function in patients with cancer. We sought to evaluate objective sleep and circadian parameters in metastatic colon cancer (MCC) patients and their associations with symptoms and quality of life (QOL).

Methods

Patients reported subjective sleep problems on the EORTC QLQ-C30. Sleep and circadian parameters were calculated using a wrist-actigraph that patients wore for 72 h.

Results

237 Patients with MCC (mean age: 60.4 years; range: 20.7–77.6; Male/Female ratio: 1.66) participated in this cross-sectional study. Subjective sleep problems were reported by 63.4% of patients (S+). No differences in any sleep parameters (sleep efficiency, sleep latency, total sleep time, total time in bed, wake after sleep onset, activity bathyphase) were observed between S+ and S? patients. However, S+ patients displayed a significantly worse circadian function than S? patients (96.4 vs 98.1%; p = 0.005). The presence of poor subjective sleep and objective circadian dysfunction negatively affected symptoms and QOL domains (p = 0.038).

Conclusions

Subjective report of sleep problems was not associated with worse objectively measured sleep parameters in patients with MCC although it was associated with disrupted circadian rest-activity rhythm and poorer QOL. These findings coincide with prior research in cancer patients in that an inconsistent relationship exists between subjective and objective sleep measurements on some sleep domains. This study supports the value of coupled evaluation of self-reported and objective measures of sleep and circadian function in cancer patients.

     

Value neutrality in genetic counseling: An unattained ideal

Beginning with a discussion of why value neutrality on the part of the genetics counselor does not necessarily preserve autonomy of the counselee, the idea that social values unavoidably underlie the articulation of risks and benefits of genetic testing is made explicit. Despite the best efforts of a counselor to convey value neutral facts, risk assessment by the counselee and family is done according to normative analysis, experience with illness, and definitions of health. Each of these factors must be known by the genetic counselor in order to relate those facts which she acknowledges as relevant to the decisions that will be made by those people seeking the genetic information.Concisely, the scope of this paper includes the role of the genetic counselor in facilitating a family planning decision-making process. In the expression of genetic risks, the authority of medical language impacts a person's understanding of epidemiological data. By claiming that value neutrality is an ethos of genetic counselors, this implies that there exists a distinction between these scientific facts and personal values; this assumption is fallacious and should not be promoted to patients as a truth within the professional ethos statement of genetic counseling.This revised version was published online in October 2005 with corrections to the Cover Date.     

Melatonin, sleep, and shift work adaptation

BACKGROUND: Night work is associated with disrupted circadian rhythms, fatigue, accidents, and chronic disease. Melatonin secretion helps regulate sleep and circadian rhythms. OBJECTIVE: Melatonin, sleep disturbances, and symptoms (sleep, fatigue, mental) were compared among workers on permanent day, swing, and night shifts. METHODS: Urinary 6-hydroxymelatonin sulfate (6-OHMS) was measured in postwork and postsleep samples. Disrupted circadian melatonin production was evaluated using the sleep:work 6-OHMS ratio. Wrist actigraphy characterized light exposures and sleep characteristics. RESULTS: Night workers had altered melatonin, disrupted sleep, and elevated symptom prevalence. Subjects grouped by their sleep:work 6-OHMS ratio rather than shift had even greater symptom prevalence. Risks for two or more symptoms were 3.5 to 8 times greater among workers with sleep:work ratios < or =1 compared to those with ratios >1. CONCLUSIONS: This ratio may help identify workers at increased risk for accidents or injuries.     

Age and adjustment to night work.

OBJECTIVE--The study was designed to examine the effects of age on sleep and the circadian rhythms during consecutive night shifts. METHODS--Two groups of letter sorters (19-29 (n = 7) and 53-59 (n = 7) years of age were studied in a sleep laboratory under closely controlled conditions. After two baseline days, circadian adjustment to three night shifts was monitored by continuous measurement of rectal temperature, salivary melatonin, and sleep-wakefulness during the night shifts. RESULTS--Age was significantly related to the adjustment to night work of rectal temperature minimum and of self rated sleepiness. Young subjects delayed their temperature phase and decreased sleepiness more than the older subjects. Age was also significantly related to an increase of alertness and to the feeling of being refreshed after the day sleep. Although there were basic differences in sleep duration and structure between the age groups, the latter did not change across the night shifts. CONCLUSION--Aging decreases the ability to recover after several, but not after the first night shift.     

Acute toxicity,percutaneous absorption and effects on hepatic mixed function oxidase activities of 2,4,4′-trichloro-2′-hydroxydiphenyl ether (Irgasan® DP300) and its chlorinated derivatives

Acute toxicity of 2,4,4-trichloro-2-hydroxydiphenyl ether (Irgasan^® DP300) (I) and its three chlorinated derivatives, 2,3,4,4-tetrachloro-2-hydroxydiphenyl ether (II), 2,4,4,5-tetrachloro-2-hydroxydiphenyl ether (III) and 2,3,4,4,5-pentachloro-2-hydroxydiphenyl ether (IV), in mice were examined by intraperitoneal injection. The LD₅₀ values of Irgasan DP300, II, III and IV were 1,090, 710, 650 and 430 mg/kg, respectively.The percutaneous absorptions of these tritiated compounds were also examined by the application on the backs of mice. The radioactivities in most tissues reached to the maximal levels at 12 h or 18 h after dosing, which corresponded to 11–76% of the maximal levels given by the oral administration (Kanetoshi et al. 1988a). These results show the high percutaneous absorbability of Irgasan DP300 and its chlorinated derivatives.The intraperitoneal administrations of III and IV to rats induced hepatic microsomal aminopyrine N-demethylase and aniline 4-hydroxylase activities similarly to phenobarbital. These chlorinated derivatives also increased cytochrome P-450 content, and the activities of aminopyrine N-demethylase and N-methylaniline N-demethylase in hepatic microsomes from mice. The extents of the increases were similar to those by phenobarbital and 3-methylcholanthrene.     

Predicting duration of sleep from the three process model of regulation of alertness.

OBJECTIVES: Irregular working hours severely disturb sleep and wakefulness. This paper presents a modification of the quantitative (computerised) three process model of regulation of alertness to predict duration of sleep in connection with irregular sleep patterns. METHODS: The model uses a circadian "C" (sinusoidal) and homeostatic "S" (exponential) component (the duration of previous periods awake and asleep), which are summed to yield predicted alertness (on a scale of 1-16). It assumes that waking from sleep will occur at a given alertness level (S' + C') when recuperation is complete. Variables of electroencephalographic duration of sleep from two studies of irregular sleep were used to model the S and C variables in a regression approach to maximise prediction. The model performance was cross validated against published field and laboratory data. RESULTS: The model parameters were defined with a high degree of precision R2 = 0.99 and the validation yielded similar values R2 = 0.98-0.95, depending on the acrophase. The paper also describes a simplified graphical version of the computation model seen as a two dimensional duration of sleep nomogram. CONCLUSION: The model seems to predict group means for duration of sleep with high precision and may serve as a tool for evaluating work and rest schedules to reduce risks of sleep disturbances.     

Measuring the impact of onychomycosis on patient quality of life

According to survey research, onychomycosis, a fungal infection of the toenail or fingernail, affects quality of life including physical and social functioning and emotional health. We developed an onychomycosis disease-specific questionnaire (ODSQ) that sensitively assessed symptom distress, functional impact, and social stigma associated with the disease. Samples of patients enrolled in a randomized controlled clinical trial were used for the psychometric evaluations. The multi-item scales were internally consistent ( 0.80) and reproducible (ICC > 0.85). Interscale correlations between the ODSQ and generic scales were moderate and consistent with the hypothesized magnitude and directions. Construct validation, employing known groups analysis, supported the hypothesized impact of onychomycosis on three domains of quality of life: physical functioning, emotional health, and social functioning. Significant differences were found between clinically cured, improved, or failed patients, and between mycologically eradicated and persistent patients. The ODSQ was responsive to clinical change and more sensitive than derived Medical Outcomes Study Short Form-36 scales. The ODSQ provides reliable, validated and responsive information about the consequences of onychomycosis and its treatment.     

Alertness management in 24/7 settings: lessons from aviation

Round-the-clock operational requirements pose physiological challenges for human operators. Fatigue due to sleep loss and circadian disruption can reduce safety, performance quality, and alertness. The authors describe the physiological factors underlying fatigue and provide examples from NASA research in aviation settings that demonstrate how fatigue affects real-world operations. A comprehensive alertness management approach to address fatigue effectively includes education, alertness strategies, scheduling, policy, and healthy sleep components. There is a need for cultural change that will encourage attitudes, behaviors, and practices that will reduce fatigue-related risks and improve safety, performance, and alertness in 24/7 operational settings.     

Utility of Subjective Sleep Assessment Tools for Healthy Preschool Children: A Comparative Study Between Sleep Logs,Questionnaires, and Actigraphy

Background

Sleep pattern is an important factor in a child’s mental, behavioural and physical status. To evaluate the sleep patterns of children, subjective tools such as sleep logs and questionnaires are still widely used in addition to objective methods of sleep assessment. Despite the established correlation between subjective and objective sleep variables, the characteristic features of subjective assessment have not been elucidated.

Methods

To investigate the characteristics of parental sleep assessment (daily sleep log and brief questionnaire) in preschool children, a 7-day actigraphic sleep study was conducted in 48 healthy 5-year-old children.

Results

Sleep schedule variables in the parental reports generally correlated well with actigraphic assessment of sleep patterns; however, sleep periods were longer in parental reports than in actigraphic recordings. Although the daily sleep log was better correlated with actigraphy, the brief questionnaire showed a good correlation with sleep pattern on weekday actigraphic assessments. Parental reports recorded fewer than 10% of the night wakings recorded by actigraphy.

Conclusions

Subjective sleep assessments remain useful, although their utility depends on the purpose and size of the study in question. However, knowledge of the potential biases and characteristics of such assessments is essential for correct interpretation of the data.Key words: actigraphy, sleep log, questionnaire, preschool child, sleep pattern, subjective sleep assessment, parental report     

The impact of extended leave on sleep and alertness in the Australian rail industry

In the past, scientific studies have investigated the effects of shift timing and duration on sleep and alertness in the rail industry. To our knowledge no research has been conducted to determine the effects of extended break lengths (>48 h) on these factors. Hence, this study analyses the work and rest schedules of 304 Australian rail employees (mean age 41.3 yr, standard deviation 7.4 yr) to determine the effect of prior break lengths (12-169 h) on sleep and subjective alertness at work after periods of leave. Extended break periods (>48 h) were found to increase the length of the sleep prior to returning to work and reduce the total wake time to the end of the first shift, but did not influence levels of subjective alertness immediately prior to the commencement of the first shift. Research into the influence of longer break periods (>169 h) is needed in order to make definitive conclusions regarding sensible return to work policies after extended leave within the Australian rail industry.     

Performance of Number-Between g-Type Statistical Control Charts for Monitoring Adverse Events

Alternate Shewhart-type statistical control charts, called g and h charts, have been developed for monitoring the number of cases between hospital-acquired infections and other adverse events, such as heart surgery complications, catheter-related infections, surgical site infections, contaminated needle sticks, medication errors and other care induced concerns. This article investigates the statistical properties of these new charts and illustrates several design considerations that significantly can improve their operating characteristics and sensitivity, including the use of with-in limit rules, a new in-control rule, redefined Bernoulli trials, and probability-based limits. These new charts are based on inverse sampling from geometric and negative binomial distributions, are simple for practitioners to use, and in some cases exhibit significantly greater detection power over conventional binomial-based approaches, particularly for infrequent events and low defect rates.     

Disturbed sleep–wake patterns during and after short-term international travel among academics attending conferences

OBJECTIVES: To examine variations in sleep and wakefulness associated with international travel. METHODS: Ten academics in Japan were studied while traveling abroad to participate in conferences. Wrist activity and a daily log were recorded continuously for 1 week before, during, and for 1 week after travel. Destinations included the USA and Canada to the east (8 to 11-h time difference; mean stay of 6.8 days) and Europe to the west (7 to 8-h time difference; mean stay of 6.0 days). RESULTS: For eastward-traveling subjects, the total sleep time was shorter and the mean activity during sleep was greater at the destinations than before departure. These sleep disruptions persisted until the 2nd day after the subjects had returned home. The sleep patterns then recovered in a zigzag manner. No significant disruptions in the main sleep were found in westward travelers, although these subjects took a longer nap immediately after their return. The beginning and end of sleep occurred earlier until the 2nd day after the subjects had returned from eastward trips, but occurred later until the 5th day after return from westward trips. CONCLUSIONS: In academics, short-term international travel causes sleep disturbances both during and at home after eastward travel and a delay in the sleep timing at home after westward travel. Although the subjects in this study might be atypical of business travelers, the current data suggest that strategies are needed to facilitate recovery from disturbed sleep-wake patterns at home after travel, i.e., redesign of post-travel work schedules.     

Analyses of neurotic symptoms and subjective symptoms of fatigue in seamen during a long voyage

The variations of neurotic symptoms and subjective symptoms of fatigue were studied in relation to circumstances aboard ship in subsamples of the crew (N = 24) and students and researchers (N = 24) of a training ship belonging to a university during a summer voyage of the North Pacific route in 1987. The data were obtained by a self-administered questionnaire administered seven times before and during the voyage. The present study analysed the data collected during the 40 d voyage (the first four questionnaires including that before departure). Complaints of neurotic symptoms and fatigue were reported to be much greater in the present sample than those in a general occupational setting. Although the complaints reported by students and researchers decreased at landing, complaints of physical fatigue reported by the crew increased at landing but those of mental fatigue hardly changed. With regard to correlation between the values of the responses to circumstances aboard ship and the values of neurotic symptoms and fatigue, "quality of sleep" was significantly correlated with these symptoms for the crew. For the students and researchers, significant correlations were demonstrated between such items as "boredom toward work" and "quality of sleep", and physical fatigue, between the "anxiety over disease" and mental fatigue and "anxiety over disease", "risk of injury" and "fear of death" and neurotic symptoms in the first survey after departure (13th day).     

Chronic Circadian Disruption and Sleep Restriction Influence Subjective Hunger,Appetite, and Food Preference

Chronic circadian disruption (CCD), such as occurs during rotating shiftwork, and insufficient sleep are each independently associated with poor health outcomes, including obesity and glucose intolerance. A potential mechanism for poor health is increased energy intake (i.e., eating), particularly during the circadian night, when the physiological response to energy intake is altered. However, the contributions of CCD and insufficient sleep to subjective hunger, appetite, food preference, and appetitive hormones are not clear. To disentangle the influences of these factors, we studied seventeen healthy young adults in a 32-day in-laboratory study designed to distribute sleep, wakefulness, and energy intake equally across all phases of the circadian cycle, thereby imposing CCD. Participants were randomized to the Control (1:2 sleep:wake ratio, n = 8) or chronic sleep restriction (CSR, 1:3.3 sleep:wake ratio, n = 9) conditions. Throughout each waking episode the participants completed visual analog scales pertaining to hunger, appetite, and food preference. A fasting blood sample was collected to assess appetitive hormones. CCD was associated with a significant decrease in hunger and appetite in a multitude of domains in both the Control and CSR groups. This change in hunger was significantly correlated with changes in the ghrelin/leptin ratio. These findings further our understanding of the contributions of CCD and insufficient sleep on subjective hunger and appetite as well as of their possible contributions to adverse health behaviors.