The endogenous circadian system worsens asthma at night independent of sleep and other daily behavioral or environmental cycles.

Asthma often worsens at night. To determine if the endogenous circadian system contributes to the nocturnal worsening of asthma, independent of sleep and other behavioral and environmental day/night cycles, we studied patients with asthma (without steroid use) over 3 wk in an ambulatory setting (with combined circadian, environmental, and behavioral effects) and across the circadian cycle in two complementary laboratory protocols performed in dim light, which separated circadian from environmental and behavioral effects: 1) a 38-h "constant routine," with continuous wakefulness, constant posture, 2-hourly isocaloric snacks, and 2) a 196-h "forced desynchrony" incorporating seven identical recurring 28-h sleep/wake cycles with all behaviors evenly scheduled across the circadian cycle. Indices of pulmonary function varied across the day in the ambulatory setting, and both laboratory protocols revealed significant circadian rhythms, with lowest function during the biological night, around 4:00 AM, uncovering a nocturnal exacerbation of asthma usually unnoticed or hidden by the presence of sleep. We also discovered a circadian rhythm in symptom-based rescue bronchodilator use (ß2-adrenergic agonist inhaler) whereby inhaler use was four times more likely during the circadian night than day. There were additive influences on asthma from the circadian system plus sleep and other behavioral or environmental effects. Individuals with the lowest average pulmonary function tended to have the largest daily circadian variations and the largest behavioral cycle effects on asthma. When sleep was modeled to occur at night, the summed circadian, behavioral/environmental cycle effects almost perfectly matched the ambulatory data. Thus, the circadian system contributes to the common nocturnal worsening of asthma, implying that internal biological time should be considered for optimal therapy.

Differences in wage rates for males and females in the health sector: a consideration of unpaid overtime to decompose the gender wage gap.

BACKGROUND: In Australia a persistent and sizable gender wage gap exists. In recent years this gap has been steadily widening. The negative impact of gender wage differentials is the disincentive to work more hours. This implies a substantial cost on the Australian health sector. This study aimed to identify the magnitude of gender wage differentials within the health sector. The investigation accounts for unpaid overtime. Given the limited availability of information, little empirical evidence exists that accounts for unpaid overtime. METHODS: Information was collected from a sample of 10,066 Australian full-time employees within the health sector. Initially, ordinary least-squares regression was used to identify the gender wage gap when unpaid overtime was included and then excluded from the model. The sample was also stratified by gender and then by occupation to allow for comparisons. Later the Blinder-Oaxaca decomposition method was employed to identify and quantify the contribution of individual endowments to wage differentials between males and females. RESULTS: The analyses of data revealed a gender wage gap that varied across occupations. The inclusion of unpaid overtime in the analysis led to a slight reduction in the wage differential. The results showed an adjusted wage gap of 16.7%. CONCLUSIONS: Unpaid overtime made a significant but small contribution to wage differentials. Being female remained the major contributing factor to the wage gap. Given that wage differentials provide a disincentive to work more hours, serious attempts to deal with the skilled labour shortage in the health sector need to address the gender wage gap.

Health-related productivity losses increase when the health condition is co-morbid with psychological distress: findings from a large cross-sectional sample of working Australians.

BACKGROUND: The health condition of workers is known to impact on productivity outcomes. The relationship between health and productivity is of increasing interest amid the need to increase productivity to meet global financial challenges. Prevalence of psychological distress is also of growing concern in Australia with a two-fold increase in the prevalence of psychological distress in Australia from 1997-2005. METHODS: We used the cross-sectional data set from the Australian Work Outcomes Research Cost-benefit (WORC) study to explore the impacts of health conditions with and without co-morbid psychological distress, compared to those with neither condition, in a sample of approximately 78,000 working Australians. The World Health Organisation Health and Performance Questionnaire was used which provided data on demographic characteristics, health condition and working conditions. Data were analysed using negative binomial logistic regression and multinomial logistic regression models for absenteeism and presenteeism respectively. RESULTS: For both absenteeism and presenteeism productivity measures there was a greater risk of productivity loss associated when health conditions were co-morbid with psychological distress. For some conditions this risk was much greater for those with co-morbid psychological distress compared to those without. CONCLUSIONS: Co-morbid psychological distress demonstrates an increased risk of productivity loss for a range of health conditions. These findings highlight the need for further research to determine whether co-morbid psychological distress potentially exacerbates lost productivity.

Patterns of multimorbidity in working Australians.

BACKGROUND: Multimorbidity is becoming more prevalent. Previously-used methods of assessing multimorbidity relied on counting the number of health conditions, often in relation to an index condition (comorbidity), or grouping conditions based on body or organ systems. Recent refinements in statistical approaches have resulted in improved methods to capture patterns of multimorbidity, allowing for the identification of nonrandomly occurring clusters of multimorbid health conditions. This paper aims to identify nonrandom clusters of multimorbidity. METHODS: The Australian Work Outcomes Research Cost-benefit (WORC) study cross-sectional screening dataset (approximately 78,000 working Australians) was used to explore patterns of multimorbidity. Exploratory factor analysis was used to identify nonrandomly occurring clusters of multimorbid health conditions. RESULTS: Six clinically-meaningful groups of multimorbid health conditions were identified. These were: factor 1: arthritis, osteoporosis, other chronic pain, bladder problems, and irritable bowel; factor 2: asthma, chronic obstructive pulmonary disease, and allergies; factor 3: back/neck pain, migraine, other chronic pain, and arthritis; factor 4: high blood pressure, high cholesterol, obesity, diabetes, and fatigue; factor 5: cardiovascular disease, diabetes, fatigue, high blood pressure, high cholesterol, and arthritis; and factor 6: irritable bowel, ulcer, heartburn, and other chronic pain. These clusters do not fall neatly into organ or body systems, and some conditions appear in more than one cluster. CONCLUSIONS: Considerably more research is needed with large population-based datasets and a comprehensive set of reliable health diagnoses to better understand the complex nature and composition of multimorbid health conditions.

Existence of an endogenous circadian blood pressure rhythm in humans that peaks in the evening.

RATIONALE: Blood pressure (BP) usually decreases during nocturnal sleep and increases during daytime activities. Whether the endogenous circadian control system contributes to this daily BP variation has not been determined under appropriately controlled conditions. OBJECTIVE: To determine whether there exists an endogenous circadian rhythm of BP in humans. METHODS AND RESULTS: In 28 normotensive adults (16 men), we assessed BP across 3 complementary, multiday, in-laboratory protocols performed in dim light, throughout which behavioral and environmental influences were controlled and/or uniformly distributed across the circadian cycle via: (1) a 38-hour "constant routine," including continuous wakefulness; (2) a 196-hour "forced desynchrony" with 7 recurring 28-hour sleep/wake cycles; and (3) a 240-hour forced desynchrony with 12 recurring 20-hour sleep/wake cycles. Circadian phases were derived from core body temperature. Each protocol revealed significant circadian rhythms in systolic and diastolic BP, with almost identical rhythm profiles among protocols. The peak-to-trough amplitudes were 3 to 6 mm Hg for systolic BP and 2 to 3 mm Hg for diastolic BP (always P<0.05). All 6 peaks (systolic and diastolic BP in 3 protocols) occurred at a circadian phase corresponding to ≈9:00 pm (ie, the biological evening). Based on substantial phase differences among circadian rhythms of BP and other variables, the rhythm in BP appeared to be unrelated to circadian rhythms in cortisol, catecholamines, cardiac vagal modulation, heart rate, or urine flow. CONCLUSIONS: There exists a robust endogenous circadian rhythm in BP. The highest BP occurred at the circadian time corresponding to ≈9:00 pm, suggesting that the endogenous BP rhythm is unlikely to underlie the well-documented morning peak in adverse cardiovascular events.

Which health conditions impact on productivity in working Australians?

OBJECTIVE: To identify health conditions associated with productivity loss in working Australians, adjusting for comorbidity, demographics, and work-related characteristics. METHODS: The Australian Work Outcomes Research Cost-benefit study cross-sectional screening data set was used to identify health-related productivity losses in a sample of approximately 78,000 working Australians. Data collected with the World Health Organisation Health and Productivity Questionnaire were analyzed using negative binomial logistic regression and multinomial logistic regression models for absenteeism and presenteeism, respectively. RESULTS: Health conditions impacted on both presenteeism and absenteeism. Drug and alcohol problems and psychological distress had a greater impact on absenteeism and presenteeism than other investigated health conditions. Demographic characteristics, health status (comorbidity), and work-related characteristics all impacted significantly on both absenteeism and presenteeism. CONCLUSION: Mental health conditions contributed more strongly to productivity loss than other investigated health conditions.

Work-related injury in the nursing profession: an investigation of modifiable factors.

AIM: This paper is a report of a correlational study of the relationships between work-related injury-risk events and modifiable risk factors in a nursing population after controlling for socioeconomic factors. BACKGROUND: Nurses are at high risk for work-related injury. Work-related injury is strongly influenced by psychosocial factors and physical job-related exposures, but the magnitude of effect from modifiable factors remains unclear. METHOD: Data were based on the Work Outcomes Research Cost-benefit survey conducted in Australia during 2005 and 2006. The study sample of 5724 represented ~14% of nurses in Queensland, Australia. Logistic regression was used to determine the magnitude of association of psychological distress (represented by the Kessler 6 score: six-item scale of psychological distress), the number of health conditions and various socioeconomic factors with work place injury. RESULTS: High psychological distress was associated with a 5% probability of injury. As the number of health conditions increased, the probability of injury increased; 3 and ≥ 6 health conditions increased the chance of injury by 5% and 15% compared with no health conditions. Compared with the total sample, nurses who reported high levels of psychological distress demonstrated greater sensitivity to the number of health conditions. Computation of the marginal effects showed little difference in the likelihood of injury when the total sample was compared with nurses with < 5 years of work experience. CONCLUSION: Effective occupational health and safety workplace programmes that target modifiable factors such as psychological distress and physical health conditions may improve the health capital of nurses and productivity levels within the profession.

Impact of the human circadian system, exercise, and their interaction on cardiovascular function.

The risk of adverse cardiovascular events peaks in the morning (≈9:00 AM) with a secondary peak in the evening (≈8:00 PM) and a trough at night. This pattern is generally believed to be caused by the day/night distribution of behavioral triggers, but it is unknown whether the endogenous circadian system contributes to these daily fluctuations. Thus, we tested the hypotheses that the circadian system modulates autonomic, hemodynamic, and hemostatic risk markers at rest, and that behavioral stressors have different effects when they occur at different internal circadian phases. Twelve healthy adults were each studied in a 240-h forced desynchrony protocol in dim light while standardized rest and exercise periods were uniformly distributed across the circadian cycle. At rest, there were large circadian variations in plasma cortisol (peak-to-trough ≈85% of mean, peaking at a circadian phase corresponding to ≈9:00 AM) and in circulating catecholamines (epinephrine, ≈70%; norepinephrine, ≈35%, peaking during the biological day). At ≈8:00 PM, there was a circadian peak in blood pressure and a trough in cardiac vagal modulation. Sympathetic variables were consistently lowest and vagal markers highest during the biological night. We detected no simple circadian effect on hemostasis, although platelet aggregability had two peaks: at ≈noon and ≈11:00 PM. There was circadian modulation of the cardiovascular reactivity to exercise, with greatest vagal withdrawal at ≈9:00 AM and peaks in catecholamine reactivity at ≈9:00 AM and ≈9:00 PM. Thus, the circadian system modulates numerous cardiovascular risk markers at rest as well as their reactivity to exercise, with resultant profiles that could potentially contribute to the day/night pattern of adverse cardiovascular events.

Employee psychological distress and treated prevalence by indices of rurality.

OBJECTIVE: Although there is population data on the prevalence and treated prevalence of mental disorders by urban-rural indices, there is a lacuna of information pertaining to employees. This paper examines the prevalence and treated prevalence of psychological distress in employees by urban-rural indicators. METHODS: Cross-sectional employee Health and Performance at Work Questionnaire responses (n=78,726 from 58 large companies) are interrogated by indices of remoteness (Accessibility/Remoteness Index of Australia), psychological distress (Kessler 6) and treatment-seeking behaviours for mental health problems. RESULTS: The overall prevalence of moderate or high psychological distress in employees was 35.2%. The prevalence varied only slightly (maximum to minimum difference of 4.6%) by rural/remote indices. Overall treatment-seeking behaviour for psychological distress was low (22.5%). The percentage of employees seeking treatment for high levels of psychological distress was the lowest in very remote regions (15.1%). CONCLUSION: Very remote employees are less likely to access mental health treatments and may be an employee subgroup that would benefit from specific employer health interventions aimed to increase treatment-seeking behaviours. IMPLICATIONS: Employees in very remote Australia could benefit from specific interventions aimed to increase mental health awareness/literacy.

Interacting with the public as a risk factor for employee psychological distress.

BACKGROUND: The 1-month prevalence of any mental disorder in employees ranges from 10.5% to 18.5%. Mental disorders are responsible for substantial losses in employee productivity in both absenteeism and presenteeism. Potential work related factors contributing to mental difficulties are of increasing interest to employers. Some data suggests that being sales staff, call centre operator, nurse or teacher increases psychological distress. One aspect of these occupations is that there is an interaction with the public. The aim of this study is to evaluate whether employees who interact with the public are at greater risk of psychological distress. METHODS: Data was collected from two studies. In study one 11,259 employees (60% female; mean age 40-years +/- SD 10-years) from six employers responded to the Health and Work Performance Questionnaire (HPQ) which contained a measure of psychological distress, the Kessler 6 (K6). Employees were coded as to whether or not they interacted with the public. Binomial logistic regression was performed on this data to determine the odds ratio (OR) for moderate or high psychological distress in employees that interacted with the public. Study two administered the HPQ and K6 to sales employees of a large Australian bank (N = 2,129; 67% female; mean age 39-years SD 10-years). This questionnaire also probed how many contacts individuals had with the public in the past week. Analysis of variance was used to determine if the number of contacts was related to psychological distress. RESULTS: In study one the prevalence of psychological distress in those that interacted and did not interact with the public were 19% and 15% respectively (P < 0.001). Interacting with the public was associated with an increased OR of 1.3 (P < 0.001) for moderate to high levels of psychological distress. In study two employees with less than 25 contacts with the public per week had a lower K6 score than those who had > or = 25 contacts per week (P = 0.016). CONCLUSIONS: The results of the current study are indicative that interaction with the public increases levels of psychological distress. Employees dealing with the public may be an employee subgroup that could be targeted by employers with mental health interventions.

Associations between psychological distress, workplace accidents, workplace failures and workplace successes.

PURPOSE: This study investigates associations between psychological distress and workplace accidents, workplace failures and workplace successes. METHODS: The Health and Work Performance Questionnaire (HPQ) was distributed to employees of 58 large employers. A total of 60,556 full-time employees were eligible for analysis. The HPQ probed whether the respondent had, in the past 30-days, a workplace accident, success or failure ("yes" or "no"). Psychological distress was quantified using the Kessler 6 (K6) scale and categorised into low, moderate and high psychological distress. Three binomial logistic regressions were performed with the dependent variables being workplace accident, success or failure. Covariates in the models were K6 category, gender, age, marital status, education level, job category, physical health and employment sector. RESULTS: Accounting for all other variables, moderate and high psychological distress significantly (P < 0.0001) increased the odds ratio (OR) for a workplace accident to 1.4 for both levels of distress. Moderate and high psychological distress significantly (P < 0.0001) increased the OR (OR = 2.3 and 2.6, respectively) for a workplace failure and significantly (P < 0.0001) decreased the OR for a workplace success (OR = 0.8 and 0.7, respectively). CONCLUSIONS: Moderate and high psychological distress increase the OR's for workplace accidents work failures and decrease the OR of workplace successes at similar levels. As the prevalence of moderate psychological distress is approximately double that of high psychological distress moderate distress consequentially has a greater workplace impact.

Work performance decrements are associated with Australian working conditions, particularly the demand to work longer hours.

OBJECTIVES: To demonstrate the importance of including a range of working conditions in models exploring the association between health- and work-related performance. METHODS: The Australian Work Outcomes Research Cost-benefit study cross-sectional screening data set was used to explore health-related absenteeism and work performance losses on a sample of approximately 78,000 working Australians, including available demographic and working condition factors. Data collected using the World Health Organization Health and Productivity Questionnaire were analyzed with negative binomial logistic regression and multinomial logistic regressions for absenteeism and work performance, respectively. RESULTS: Hours expected to work, annual wage, and job insecurity play a vital role in the association between health- and work-related performance for both work attendance and self-reported work performance. CONCLUSIONS: Australian working conditions are contributing to both absenteeism and low work performance, regardless of health status.

Using the interaction of mental health symptoms and treatment status to estimate lost employee productivity.

OBJECTIVE: In Australia it has been estimated that mental health symptoms result in a loss of $ AU2.7 billion in employee productivity. To date, however, there has been only one study quantifying employee productivity decrements due to mental disorders when treatment-seeking behaviours are considered. The aim of the current paper was to estimate employee work productivity by mental health symptoms while considering different treatment-seeking behaviours. METHOD: A total of 60 556 full-time employees responded to the World Health Organization Health and Work Performance Questionnaire. This questionnaire is designed to monitor the work productivity of employees for chronic and acute physical and mental health conditions. Contained within the questionnaire is the Kessler 6, a scale measuring psychological distress along with an evaluation of employee treatment-seeking behaviours for depression, anxiety and any other emotional problems. A univariate analysis of variance was performed for employee productivity using the interaction between Kessler 6 severity categories and treatment-seeking behaviours. RESULTS: A total of 9.6% of employees have moderate psychological distress and a further 4.5% have high psychological distress. Increasing psychological distress from low to moderate then to high levels is associated with increasing productivity decrements (6.4%, 9.4% and 20.9% decrements, respectively) for employees in current treatment. Combining the prevalence of Kessler 6 categories with treatment-seeking behaviours, mean 2009 salaries and number of Australian employees in 2009, it is estimated that psychological distress produces an $ AU5.9 billion reduction in Australian employee productivity per annum. CONCLUSIONS: The estimated loss of $ AU5.9 billion in employee productivity due to mental health problems is substantially higher than previous estimates. This finding is especially pertinent given the global economic crisis, when psychological distress among employees is likely to be increasing. Effective treatment for mental health problems yields substantial increases in employee productivity and would be a sound economic investment for employers.

The association between mental disorders and productivity in treated and untreated employees.

OBJECTIVES: In a large cross-sectional study, this article investigates associations between employee work productivity, psychological distress, and the treatment of mental disorders. METHODS: Sixty thousand five hundred fifty-six Australian employees completed the Health and Work Performance Questionnaire (HPQ). The HPQ quantified treatment seeking behavior for depression, anxiety, or other mental disorders. The HPQ also evaluated the level of psychological distress (Kessler 6 [K6]) and employee productivity measures. RESULTS: The productivity of employees without psychological distress and who have not been in treatment of a mental disorder was 20% (SE = 0.3%). The productivity of a successfully treated employee (low K6) for a mental disorder was 17% (SE = 0.6%). CONCLUSIONS: Treatment of mental disorders resulting in normalization of symptoms is associated with employees' productivity returning to values approaching those of employees without a history of a mental disorder.

The impact of mental health symptoms on heavy goods vehicle drivers' performance.

High levels of psychological distress in fulltime employees are prevalent (4.5% per month). Symptoms of impaired mental health include difficulties with attention, concentration, motivation, decision-making, visuo-motor control, and psychomotor reaction times. There is limited research on the impact these symptoms have on heavy goods vehicle (HGV) drivers' performance. In this study 1324 HGV drivers were surveyed using the Depression, Anxiety, Stress Scale (DASS) and the Health and Performance at Work Questionnaire (HPQ). Depression, anxiety and stress had little effect on driver absenteeism rates or self-rated driving performance. However, severe (1.5% of drivers) and very severe (1.8% of drivers) depression was associated with an increased odds ratio (OR=4.5 and 5.0, respectively) for being involved in an accident or near miss in the past 28 days. This odd ratio is akin to driving with a blood alcohol content of about 0.08%. Given the number of HGV vehicles and the prevalence of depression this equates to 10,950 HGV drivers with an increased statistical risk of an accident or near miss. As the impact of HGV accidents is potentially large, including loss of life, it would be sensible to extend the research findings here into an action plan.

Adverse metabolic and cardiovascular consequences of circadian misalignment.

There is considerable epidemiological evidence that shift work is associated with increased risk for obesity, diabetes, and cardiovascular disease, perhaps the result of physiologic maladaptation to chronically sleeping and eating at abnormal circadian times. To begin to understand underlying mechanisms, we determined the effects of such misalignment between behavioral cycles (fasting/feeding and sleep/wake cycles) and endogenous circadian cycles on metabolic, autonomic, and endocrine predictors of obesity, diabetes, and cardiovascular risk. Ten adults (5 female) underwent a 10-day laboratory protocol, wherein subjects ate and slept at all phases of the circadian cycle-achieved by scheduling a recurring 28-h "day." Subjects ate 4 isocaloric meals each 28-h "day." For 8 days, plasma leptin, insulin, glucose, and cortisol were measured hourly, urinary catecholamines 2 hourly (totaling approximately 1,000 assays/subject), and blood pressure, heart rate, cardiac vagal modulation, oxygen consumption, respiratory exchange ratio, and polysomnographic sleep daily. Core body temperature was recorded continuously for 10 days to assess circadian phase. Circadian misalignment, when subjects ate and slept approximately 12 h out of phase from their habitual times, systematically decreased leptin (-17%, P < 0.001), increased glucose (+6%, P < 0.001) despite increased insulin (+22%, P = 0.006), completely reversed the daily cortisol rhythm (P < 0.001), increased mean arterial pressure (+3%, P = 0.001), and reduced sleep efficiency (-20%, P < 0.002). Notably, circadian misalignment caused 3 of 8 subjects (with sufficient available data) to exhibit postprandial glucose responses in the range typical of a prediabetic state. These findings demonstrate the adverse cardiometabolic implications of circadian misalignment, as occurs acutely with jet lag and chronically with shift work.

Employee absenteeism measures reflecting current work practices may be instrumental in a re-evaluation of the relationship between psychological distress/mental health and absenteeism.

Absenteeism rates are the cornerstone metrics guiding corporate policy for health care investment in employees. However, traditional absenteeism measures do not reflect the contemporary workplace milieu. It is accepted practice that employees work evenings or weekends to makeup time. Using a hours-based absenteeism measure, that accounts for time made-up as well as time lost, this paper evaluates the impact of psychological distress on employee absenteeism.Psychological distress and absenteeism data were collected from 54,264 full-time employees. Consistent with traditional approaches, employees indicated how many days they were absent. Hours based absenteeism was formulated from the ratio of how many hours the employees worked and how many hours were they expected to work in the past seven-days.Concordant with previous concinnous evidence, traditional absenteeism computation indicated that elevated psychological distress is associated with increasing absenteeism. Using the hours-based method psychological distress did not significantly influence absenteeism.Traditional calculations of absenteeism do not reflect the current work practices of the majority of employees. Employees with psychological distress may take time off work but it appears that they make up for lost time possibly to stay up to speed with task driven occupations and avoid performance review.

Mental ill-health and the differential effect of employee type on absenteeism and presenteeism.

OBJECTIVE: Mental ill-health results in substantial reductions in employee productivity (absenteeism and presenteeism). This paper examines the relationship between employee psychological distress, employee type and productivity. METHOD: Utilizing the Health and Performance at Work Questionnaire, in a sample of 60,556 full-time employees, the impact that psychological distress (Kessler 6) imposes on employee productivity by occupation type is examined. RESULTS: Comparison of white-collar workers absenteeism rates by low and high psychological distress reveals no statistically significant difference. Nevertheless, the same comparison for blue-collar workers reveals that high psychological distress results in an 18% increase in absenteeism rates. High K6 score resulted in a presenteeism increase of 6% in both blue and white-collar employees. CONCLUSION: The novel finding is that mental ill-health produces little to no absenteeism in white-collar workers yet a profound absenteeism increase in the blue-collar sector.

An endogenous circadian rhythm in sleep inertia results in greatest cognitive impairment upon awakening during the biological night.

Sleep inertia is the impaired cognitive performance immediately upon awakening, which decays over tens of minutes. This phenomenon has relevance to people who need to make important decisions soon after awakening, such as on-call emergency workers. Such awakenings can occur at varied times of day or night, so the objective of the study was to determine whether or not the magnitude of sleep inertia varies according to the phase of the endogenous circadian cycle. Twelve adults (mean, 24 years; 7 men) with no medical disorders other than mild asthma were studied. Following 2 baseline days and nights, subjects underwent a forced desynchrony protocol composed of seven 28-h sleep/wake cycles, while maintaining a sleep/wakefulness ratio of 1:2 throughout. Subjects were awakened by a standardized auditory stimulus 3 times each sleep period for sleep inertia assessments. The magnitude of sleep inertia was quantified as the change in cognitive performance (number of correct additions in a 2-min serial addition test) across the first 20 min of wakefulness. Circadian phase was estimated from core body temperature (fitted temperature minimum assigned 0 degrees ). Data were segregated according to: (1) circadian phase (60 degrees bins); (2) sleep stage; and (3) 3rd of the night after which awakenings occurred (i.e., tertiary 1, 2, or 3). To control for any effect of sleep stage, the circadian rhythm of sleep inertia was initially assessed following awakenings from Stage 2 (62% of awakening occurred from this stage; n = 110). This revealed a significant circadian rhythm in the sleep inertia of cognitive performance (p = 0.007), which was 3.6 times larger during the biological night (circadian bin 300 degrees , approximately 2300-0300 h in these subjects) than during the biological day (bin 180 degrees , approximately 1500-1900 h). The circadian rhythm in sleep inertia was still present when awakenings from all sleep stages were included (p = 0.004), and this rhythm could not be explained by changes in underlying sleep drive prior to awakening (changes in sleep efficiency across circadian phase or across the tertiaries), or by the proportion of the varied sleep stages prior to awakenings. This robust endogenous circadian rhythm in sleep inertia may have important implications for people who need to be alert soon after awakening.

The prevalence of psychological distress in employees and associated occupational risk factors.

OBJECTIVE: There is limited occupational health industry data pertaining to 1) the prevalence of psychological distress in various employee subtypes and 2) risk factors for employee psychological distress. METHOD: The employees of 58 large public and private sector employers were invited to complete the Kessler 6 (K6) as part of the Health and Performance at Work Questionnaire. A K6 score of > or =13 was chosen to indicate high psychological distress. RESULTS: Data on 60,556 full-time employees indicate that 4.5% of employees have high psychological distress of which only 22% were in current treatment. Occupational risk factors identified include long working hours, sales staff and non-traditional gender roles. CONCLUSION: High psychological distress is pervasive across all employee subtypes and remains largely untreated. Risk factors identified will guide the targeting of mental health promotion, prevention and screening programs.