Click for next page ( 123


The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 122
125 REFERENCE SUMMARIES** Reviewer: Susan Buchanan Complete Title: The Impact of Daily Sleep Duration on Health: A Review of the Literature. Alvarez, G.G., Ayas, N.T. Prog Cardiovasc Nurs 2004;19(2): 5659. Abstract: A healthy amount of sleep is paramount to leading a healthy and productive lifestyle. Although chronic sleep loss is common in today's society, many people are unaware of the potential adverse health effects of habitual sleep restriction. Under strict experimental con- ditions, short-term restriction of sleep results in a variety of adverse physiologic effects, including hypertension, activation of the sympathetic nervous system, impairment of glu- cose control, and increased inflammation. A variety of epidemiologic studies have also sug- gested an association between self-reported sleep duration and long-term health. Individu- als who report both an increased (>8 h/d) or reduced (<7 h/d) sleep duration are at modestly increased risk of all-cause mortality, cardiovascular disease, and developing symptomatic diabetes. Although the data are not definitive, these studies suggest that sleep should not be considered a luxury, but an important component of a healthful lifestyle. Methodology: This was not a scientific study. It was a review article, but not a methodic literature review. Scope of Work: To discuss the physiologic effects of short-term and long-term sleep restriction and exam- ine the relationship between sleep restriction or sleep excess and a variety of health out- comes such as all-cause mortality, coronary heart disease (CHD), and diabetes. Findings Directly Related Driver Health (General) to HOS (include page references): On short-term sleep restriction: mentions Spiegel's article (reviewed for Part II) showing impaired glucose tolerance and reduced leptin, etc., with acute sleep deprivation as well as another study by Meier-Ewert showing increased C-reactive protein with 4.2 hours of sleep per night. "Although the magnitude of the physiologic changes found in these short-term studies was modest, they provide a potential mechanism whereby long-term sleep restriction may affect long-term health. However, the experiments described above predominantly studied young, healthy subjects and it is not known if similar changes would be found in older subjects." (There were no page numbers in e-file.) On long-term sleep restriction: mentions the Nurses Health Study by Ayas showing a sig- nificantly increased risk of cardiovascular disease with 5 hours of sleep per night. Another article by Ayas using the same cohort (reviewed for Part II) which examined the risk of dia- betes, was noted for its lack of significant association after adjusting for multiple co-variates. Also noted was the fact that these studies were done on women only so they should not apply to men. They were also criticized for using self-reports of sleep duration and for pos- sible residual confounding. Longer sleepers: several studies note increased mortality, not useful for our purposes. Reviewer's Notes: This article is a review of the literature on health effects of sleep deprivation. It supports the findings of other studies reviewed for Part II, specifically the Spiegel and Ayas articles. **Summaries are provided in the order submitted by the researchers.

OCR for page 122
126 Reviewer: Susan Buchanan Complete Title: A Prospective Study of Self-Reported Sleep Duration and Incident Diabetes in Women. Najib T. Ayas, MD, David P. White, MD, Wael K. Al-Delaimy, MD, PhD., Joann E. Manson, MD, DRPH, Meir J. Stampfer, MD, DRPH, Frank E. Speizer, MD, Sanjay Patel, MD, Frank B. Hu, MD, PhD. Diabetes Care 26:380384, 2003. Abstract: Short-term sleep restriction results in impaired glucose tolerance. To test whether habitu- ally short sleep duration increases the risk of developing diabetes, we studied a cohort of 70,026 women enrolled in the Nurses Health Study, without diabetes at baseline, and who responded to a question about daily sleep duration in 1986. Subjects were followed until 1996 for the diagnosis of diabetes (1,969 cases). Long and short sleep durations were asso- ciated with an increased risk of diabetes diagnosis. The relative risks (RRs) for short (slept 9 h per day) sleepers were 1.57 (95% CI 1.281.92) and 1.47 (1.191.80), respectively. After adjustment for BMI and a variety of confounders, the RR was not significantly increased for short sleepers (1.18 [0.961.44]) but remained modestly increased for long sleepers (1.29 [1.050.59]). We then performed a similar analysis using only symptomatic cases (n = 1,187). Adjusted RRs for symptomatic diabetes were mod- estly elevated in both short (1.34 [1.041.72]) and long (1.35 [1.041.75]) sleepers. Our data suggest that the association between a reduced self-reported sleep duration and dia- betes diagnosis could be due to confounding by BMI or sleep restriction may mediate its effects on diabetes through weight gain. Sleep restriction may be an independent risk fac- tor for developing symptomatic diabetes. Methodology: The Nurses Health Study Cohort was used. In 1986, subjects were asked about total hours of sleep. Between 1986 and 1996, the incidence of diabetes was assessed with a supple- mentary questionnaire (to confirm the diagnosis). Relative risk for diabetes was calculated in the different categories of exposure (hours of sleep per night), adjusted for age. Multi- variate analysis included age, smoking status, hypertension, alcohol consumption, physical activity, menopausal status, family history of diabetes, and hyperlipidemia. BMI was adjusted for in secondary analysis. Scope of Work: To assess the relationship between self-reported sleep duration and the diagnosis of diabetes. Sample Size: 70,026 nurses in the United States Industry Sector: Nurses Major Limitations: Old criterion for diabetes was used (FBS < 140). Current diagnostic criteria are stricter and would have resulted in more cases of diabetes, if used. Findings Directly Related Driver Health (General) to HOS (include page references): Those who slept 5 or 6 hours per night showed significantly elevated relative risks (adjusted for age.) After adjusting for covariates, results remained significant but attenu- ated. After adjustment for BMI, the short sleepers were no longer at risk. Reviewer's Notes: Results were modest and disappeared when adjusted for BMI, a known risk factor for dia- betes. A modest study (due to the results, not the design).

OCR for page 122
127 Reviewer: Susan Buchanan Complete Title: Quantitative Risk Assessment of Lung Cancer Risk from Diesel Exhaust Exposure in the U.S. Trucking Industry: A Feasibility Study. Garshick, E., Smith, T.J., Laden, F. Health Effects Institute Diesel Epidemiology Working Group 2002. pp. 115149. Abstract: The objectives of this study were to test the feasibility of identifying a population exposed to diesel exhaust in which small to moderate excesses in lung cancer could be estimated with reasonable precision and to develop a strategy to provide quantitative estimates of cur- rent and past exposures. We chose to assess the feasibility of designing an epidemiologic study based in the U.S. trucking industry. With cooperation of the Motor Freight Carriers Association (the trucking industry trade association) and the International Brotherhood of Teamsters (Teamsters Union), 4 large unionized national trucking companies agreed to par- ticipate in the feasibility study. We obtained samples of personnel, payroll, and truck inven- tory records and interviewed long-term employees, record managers, and senior manage- ment. The types of retirement records available from 2 large Teamsters union pension funds were determined. A pilot questionnaire was mailed to 526 employees at one terminal to obtain information on smoking behavior and job history. Short-term variations in exposure were assessed by measurement of air quality in truck cabs, loading docks, and yards in 2 large urban terminals and 4 small rural terminals. Measurements included elemental car- bon (EC*) and organic carbon (OC) particles 2.5 m or smaller in diameter, and respirable particulate clusters 2.5 m or smaller in aerodynamic diameter (PM2.5). The OC collected in high-volume area samples was further analyzed to assess the extent to which particles collected in the loading dock area came from diesel vehicles. Past studies and outside expo- sure databases were reviewed. Major determinants of exposure included an individual's job title, terminal size, and termi- nal location. A gradient of exposure was identified. Smoking behavior did not differ between long-haul drivers and other workers. In 1985, the number of male union workers at the 4 companies whose job history could be characterized was 55,750, and in 1999, it was 72,666. A retrospective cohort study of workers from the cooperating trucking com- panies and the Teamsters union alive in 1985 with mortality assessed through 2000 would have a greater than an 80% power to detect a relative risk of lung cancer of 1.25 to 1.29 attributable to diesel exposure. Thus, epidemiologic studies can be designed to study the occurrence of lung cancer and to estimate past exposures to diesel exhaust among employ- ees of the trucking industry. Methodology: The four largest unionized trucking companies in the U.S. were used to assess the quality of records of personnel, equipment, payroll, operations, and retirement in order to recon- struct job and exposure histories. Exposure was assessed at 2 large terminals in an urban area and at 4 small terminals in rural New England. Personnel database assessment included work history records and Teamsters Union employment records. Assessment of company data of truck fleets included inventory and maintenance records, vehicle purchasing, and retirement. Terminals were assessed for design, operations, and location (urban, rural). Field tests, including both personal and fixed location sampling, were conducted to obtain some limited data on current exposures to diesel exhaust. Scope of Work: To determine the feasibility of designing an epidemiologic study to assess lung cancer risk from long-term exposure to diesel exhaust for the purpose of hazard identification and risk assessment based on exposure estimates. Sample Size: Thirty workers in the pilot exposure measurement part of the study. Four trucking compa- nies with a total of 72,666 workers were included in the feasibility assessment. 526 employ- ees participated in the pilot questionnaire part of the study.

OCR for page 122
128 Industry Sector: Trucking industry, both short and long haul Major Limitations: This is a feasibility study only. The data collected were for use in estimating feasibility and not for investigating the association between exposure to diesel exhaust and lung cancer. Findings Directly Related Working Conditions (Environmental except sleeper berth) to HOS (include page references): Long-haul drivers had the lowest and dock workers had the highest exposure levels to organic carbon, PM2.5 and elemental carbon (n = 30). However, when looking at correla- tion between the levels, "Assuming that EC represents diesel exposure in these settings, these results show that PM 2.5 would be a poor marker of diesel exposure and the OC would add little information (although the sampling numbers are small.)" (p. 131) Regarding area samples: "These data show that even in rural locations the existence of diesel sources near the terminal can increase exposure levels." (p. 132) Comparison to NIOSH Health Hazard Evaluation exposure data (Zaebst 1989): "Exposures of long haul drivers were much lower in our Atlanta data than in the Zaebst data, which may reflect the effect of new diesel technology." (p. 134) Regarding estimation of previous exposures: "For this cohort, the results showed that job alone might give highly misclassified exposure assignments. This definition should be refined by including terminal characteristics and formulating job-terminal exposure categories for historical periods." (p. 138) Power calculations were presented for 3 exposure scenarios and demonstrated the feasibil- ity of detecting a significant trend across exposure groups with relative risks of 1.271.33 at 80% power. Reviewer's Notes: This is a feasibility study only. The data collected were for use in estimating feasibility and not for investigating the association between exposure to diesel exhaust and lung cancer.

OCR for page 122
129 Reviewer: Susan Buchanan Complete Title: Occupational Exposure and Lung Cancer risk: A Population-Based Case-Referent Study in Sweden. Am J Epidemiol. 2000 Jul 1;152(1):3240. Gustavsson, P., Jakobsson, R., Nyberg, F., Pershagen, G., Jarup, L., Scheele, P. Abstract: This case-referent study investigated the lung cancer risk from occupational exposure to diesel exhaust; mixed motor exhaust; other combustion products, asbestos, metals, oil mist, and welding fumes. All cases of lung cancer in males aged 40 to 75 years old among stable residents of Stockholm County, Sweden, were identified from 1985 to 1990. Refer- ents were selected as a stratified (age, inclusion year) random sample. Information on life- time occupational history, residency, and tobacco smoking was obtained from the study subjects or from next of kin. Response rates of 87% and 85% resulted in 1,042 cases and 2,364 referents, respectively. Occupational exposures were assessed by an occupational hygienist who coded the intensity and probability of each exposure. Risk estimates were adjusted for tobacco smoking, other occupational exposures, residential radon, and envi- ronmental exposure to traffic-related air pollution. For the highest quartile of cumulative exposure versus no exposure, the relative risk was 1.63 (95% confidence interval (CI): 1.14, 2.33) for diesel exhaust, 1.60 (95% CI: 1.09, 2.34) for combustion products, and 1.68 (95% CI: 1.15, 2.46) for asbestos. Dose-response analyses indicated an increase in lung cancer risk of 14% per fiber-year/ml for asbestos exposure. No increased risk was found for the other exposure factors. An overall attributable proportion of 9.5% (95% CI: 5.5, 13.9) was estimated for lung cancer related to diesel exhaust, other combustion products, and asbestos. Methodology: The population included all men aged 40 to 75 years old who were residents of Stockholm County, Sweden, at any time between 1985 and 1990. All cases of lung cancer diagnosed in that time period were identified from the regional cancer registry. Controls were ran- domly selected from population registers and matched for age and year of inclusion. A postal questionnaire was sent to all study subjects and included information on lifetime occupational history, residential history, smoking habits and other risk factors for lung can- cer. An industrial hygienist assessed the intensity and probability of exposure to occupa- tional exposure factors for every subject on a case-by-case basis and based the assessment on personal contacts, personal experience, and reports of exposure levels specific for occu- pation. Nitrogen dioxide was used as an indicator for exposure to diesel exhaust. The relative risks of developing lung cancer were estimated by unconditional regression. Smoking was controlled for. Environmental levels of nitrogen dioxide were used to esti- mate non-occupational exposure to air pollutants from road traffic. Indoor radon exposure was estimated using geographic data on ground levels of radon. Scope of Work: To investigate the lung cancer risk from occupational as well as environmental exposures, using detailed individual exposure data. This paper focused on lung cancer risk in relation to seven occupational exposure factors: diesel exhaust, mixed motor exhaust, combustion products, asbestos, metals, oil mist, and welding fumes. Results regarding environmental exposures were published separately. Sample Size: 1,042 cases and 2,364 controls Industry Sector: General population Major Limitations: Exposure estimates performed by only one industrial hygienist

OCR for page 122
130 Findings Directly Related Working Conditions (Environmental except sleeper berth) to HOS (include page references): "Slightly increased relative risks were observed in the highest estimated exposure to mixed motor exhaust and to intermediate exposure to diesel exhaust." (p. 6 of 14) "Increased risks of lung cancer were noted in the highest quartiles of cumulative exposure to diesel exhaust, combustion products and asbestos. The risk associated with exposure to diesel exhaust was affected neither by adjustment for smoking habits nor by adjustment for exposure to combustion products and asbestos." (p. 6 of 14) "A positive dose-response relationship was noted for diesel exhaust." (p. 7 of 14) "The present findings add further evidence for an association between diesel exhaust and lung cancer" (p. 9 of 14) Reviewer's Notes: This is a study adding to the literature on the association between exposure to diesel exhaust and lung cancer. Typical biases in questionnaire studies were controlled for and risk esti- mates for lung cancer adjusted for smoking, radon exposure, and ambient nitrogen dioxide levels (as an indicator of road traffic air pollution).

OCR for page 122
131 Reviewer: Susan Buchanan Complete Title: Executive Summary, Diesel Emissions and Lung Cancer: Epidemiology and Quantitative Risk Assessment. Health Effects Institute 1999. Abstract: n/a Methodology: Not given in executive summary Scope of Work: (1) to review the epidemiologic data that form the basis of current quantitative risk assess- ments, (2) to identify data gaps and sources of uncertainty, (3) make recommendations about the usefulness of extending or conducting further analyses of existing data sets, and (4) make recommendations for the design of new studies that would provide a stronger basis for risk assessment. "It [the panel] was not charged to evaluate either the broad toxicologic or epidemiologic literature concerning exposure to diesel exhaust and lung cancer for haz- ard identification purposes, which has been done by others." (p. 1) Sample Size: n/a Industry Sector: n/a Major Limitations: This was a limited evaluation of the literature. Findings Directly Related Driver Health (General) to HOS (include page references): "At present, the railroad worker cohort study (Garshick et al. 1988), though part of a larger body of hazard identification studies, has very limited utility for QRA of lifetime lung can- cer risk from exposure to ambient levels of diesel exhaust . . ." (p. 4) "The investigators' analysis of the teamster data reported an exposure-response relation (Steenland et al. 1998) that may be useful for QRA; this relation will be better understood with further exploration of uncertainties and assumptions, particularly those relating to the reconstruction of past exposures and the selection of controls." (p. 4) Reviewer's Notes: This summarizes the work of the Diesel Epidemiology Project of the Health Effects Institute (HEI) which set out to address the 4 issues listed above. It does not evaluate the evidence associating diesel exhaust with lung cancer, but it does comment on studies (Steenland and Garshick) reviewed for the HOS literature search in Part I.

OCR for page 122
132 Reviewer: Susan Buchanan Complete Title: Mortality Associated with Sleep Duration and Insomnia. Kripke, D.F., Garfinkel, L., Wingard, D., Klauber, M., Marler, M. Arch Gen Psych 59. 131136. 2002. Abstract: Background: Patients often complain about insufficient sleep or chronic insomnia in the belief that they need 8 hours of sleep. Treatment strategies may be guided by what sleep durations predict optimal survival and whether insomnia might signal mortality risks. Methods: In 1982, the Cancer Prevention Study II of the American Cancer Society asked participants about their sleep duration and frequency of insomnia. Cox proportional haz- ards survival models were computed to determine whether sleep duration or frequency of insomnia was associated with excess mortality up to 1988, controlling simultaneously for demographics, habits, health factors, and use of various medications. Results: Participants were more than 1.1 million men and women from 30 to 102 years of age. The best survival was found among those who slept 7 hours per night. Participants who reported sleeping 8 hours or more experienced significantly increased mortality hazard, as did those who slept 6 hours or less. The increased risk exceeded 15% for those reporting more than 8.5 hours sleep or less than 3.5 or 4.5 hours. In contrast, reports of "insomnia" were not associated with excess mortality hazard. As previously described, prescription sleeping pill use was associated with significantly increased mortality after control for reported sleep durations and insomnia. Conclusions: Patients can be reassured that short sleep and insomnia seem associated with little risk distinct from comorbidities. Slight risks associated with 8 or more hours of sleep and sleeping pill use need further study. Causality is unproven. Methodology: The Cancer Prevention Study of the American Cancer Society (CSPII) provided data from 1.1 million participants who completed health questionnaires in 1982. Survival or date of death was ascertained 6 years later. 32 covariates were entered into the models of sleeping duration and mortality risk. Scope of Work: To explore whether sleep duration predicts mortality. Sample Size: 636,095 men and 480,841 women Industry Sector: General population Major Limitations: n/a Findings Directly Related Driver Health (General) to HOS (include page references): "Among both women and men, the best survival was experienced by those reporting a usual sleep duration of 7 hours." (p. 5 of 10) " Reported sleep had to be less than 3.5 hours among women and less than 4.5 hours among men for the added risk associated with short sleep to exceed 15%." (p. 5 of 10) "Comparison of the 32-covariate models with the simplified CPSII models and the less- controlled CPSI tabulations showed that most mortality risk associated with short sleep could be explained by comorbidities." (p. 6 of 10) Reviewer's Notes: Short sleep duration of as low as 4.5 hours does not affect mortality. This study offers an opposing view to the studies showing adverse health effects of sleep deprivation.

OCR for page 122
133 Reviewer: Susan Buchanan Complete Title: The relative importance of whole body vibration and occupational lifting as risk factors for low-back pain. K.T. Palmer, M.J. Griffin, H.E. Syddall, B. Pannett, C. Cooper, D. Coggon. Occup Environ Med 2003;60:715721. Abstract: Aims: To explore the impact of occupational exposure to whole body vibration (WBV) on low back pain (LBP) in the general population and to estimate the burden of LBP attribut- able to occupational WBV in comparison with that due to occupational lifting. Methods: A questionnaire including sections on WBV at work, LBP, and potential risk factors was mailed to a community sample of 22,194 men and women of working age. Sources and durations of exposure to occupational WBV were ascertained for the past week and per- sonal vibration doses (eVDV) were estimated. Analysis was confined to subjects reporting exposures in the past week as typical of their work. Associations of LBP with eVDV, driv- ing industrial vehicles, and occupational lifting were explored by logistic regression and attributable numbers were calculated. Results: Significant associations were found between daily lifting of weights greater than 10 kg at work and LBP, troublesome LBP (which made it difficult to put on hosiery), and sciatica (prevalence ratios 1.3 to 1.7); but the risk of these outcomes in both sexes varied little by eVDV and only weak associations were found with riding on industrial vehicles. Assuming causal associations, the numbers of cases of LBP in Britain attributable to occupational WBV were estimated to be 444,000 in men and 95,000 in women. This compared with an estimated 940,000 male cases and 370,000 female cases of LBP from occupational lifting. Conclusions: The burden of LBP in Britain from occupational exposure to WBV is smaller than that attributable to lifting at work. Methodology: A postal survey was sent to 22,194 adults in Britain regarding exposure to vibration and health. Subjects were selected at random from patient lists of general practices and from members of the armed services randomly selected from pay records. Exposure to vibration was assessed by asking about driving or riding any of a checklist of vehicles. Duration of exposure was also assessed. Logistic regression was adjusted for non-occupational expo- sure to WBV. Scope of Work: To assess the burden of LBP caused by exposure to WBV and to compare it with LBP caused by heavy lifting. Questionnaires were sent to general public and armed services in Britain. Sample Size: 4,250 men and 3,061 women were included in the final analysis. Industry Sector: n/a Major Limitations: Exposure was assessed by questionnaire only. May have response bias; those with back pain or exposure to vibration were more likely to complete the survey. Findings Directly Related Working Conditions (Environmental except sleeper berth) to HOS (include page references): Very weak association found between estimated vibration dose and presence of low back pain. "The data on WBV do not provide strong evidence to suggest a cause-effect relation (and do not distinguish the risks of sitting and driving from those of merely sitting)." (p. 717) "Use of industrial vehicles in general did not appear to confer an increased risk in men." A significant association was found in women, although many fewer women had these exposures. Reviewer's Notes: Studies using populations of exposed workers instead of just the general population show stronger associations between WBV and low back pain. This may be due to the multiple possibilities for bias inherent in a cross-sectional survey of the general population.

OCR for page 122
134 Reviewer: Susan Buchanan Complete Title: Impact of sleep debt on metabolic and endocrine function. Spiegel, K., Leproult, R., Van Cauter, E. Lancet 1999;354:14351439. Abstract: Background: Chronic sleep debt is becoming increasingly common and affects millions of people in more-developed countries. Sleep debt is currently believed to have no adverse effect on health. We investigated the effect of sleep debt on metabolic and endocrine func- tions. Methods: We assessed carbohydrate metabolism, thyrotropic function, activity of the hypothalamo-pituitary-adrenal axis, and sympathovagal balance in 11 young men after time in bed had been restricted to 4 h per night for 6 nights. We compared the sleep-debt condi- tion with measurements taken at the end of a sleep-recovery period when participants were allowed 12 h in bed per night for 6 nights. Findings: Glucose tolerance was lower in the sleep-debt condition than in the fully rested condition (p < 0.02), as were thyrotropin con- centrations (p<0.01). Evening cortisol concentrations were raised (p = 0.0001) and activity of the sympathetic nervous system was increased in the sleep-debt condition (p < 0.02). Interpretation: Sleep debt has a harmful impact on carbohydrate metabolism and endocrine function. The effects are similar to those seen in normal aging and, therefore, sleep debt may increase the severity of age-related chronic disorders. Methodology: Eleven healthy young men spent 16 nights in the clinical research center. For the first 3 nights, they spent 8 hours in bed; for 6 nights, they were in bed for 4 hours; and the last 7 nights, they were in bed for 12 hours. They were assessed for carbohydrate metabolism and hormonal profiles and compared sleepiness, sympathovagal balance, and saliva-free cortisol concentrations in all three conditions. Scope of Work: To evaluate the metabolic and hormonal variables in people in whom sleep had been restricted and extended. Sample Size: 11 healthy volunteers Industry Sector: n/a Major Limitations: Very small population. (n = 11) Limited population (healthy young men) Findings Directly Related Driver Health (General) to HOS (include page references): "During the sleep-debt condition, responses were consistent with a clear impairment of car- bohydrate tolerance." (p.1437) "The normal rise in thyrotropin at night was strikingly decreased in the sleep-debt condi- tion compared with that in the sleep-recovery condition . . ." (p. 1438) "Based on the analysis of the concentrations of free cortisol in saliva, the rate of decrease of free cortisol concentrations between 1600 h and 2100h was about six times slower in the sleep-debt condition than in the sleep-recovery condition." (p. 1438) "Therefore, although the primary function of sleep may be cerebral restoration, sleep debt also has consequences for peripheral function that, if maintained chronically, could have long-term adverse effects on health." "The metabolic and endocrine alterations seen during the sleep-debt condition therefore mimic some of the hallmarks of aging, which suggests that chronic sleep loss could increase the severity of age-related pathologies, such as dia- betes and hypertension." (p. 1438) Reviewer's Notes: Changes in metabolic function seen during sleep deprivation in this study are similar to that seen in patients with type 2 diabetes. Changes in cortisol levels with sleep deprivation are similar to that seen in normal aging.

OCR for page 122
135 Reviewer: Susan Buchanan Complete Title: Short Sleep Duration Is Associated with Reduced Leptin, Elevated Ghrelin, and Increased Body Mass Index. Shahrad Taheri, Ling Lin, Diane Austin, Terry Young, and Emmanuel Mignot Plos Med. 2004 December; 1(3): e62. Abstract: Sleep duration may be an important regulator of body weight and metabolism. An associ- ation between short habitual sleep time and increased body mass index (BMI) has been reported in large population samples. The potential role of metabolic hormones in this asso- ciation is unknown. Methods and Findings: Study participants were 1,024 volunteers from the Wisconsin Sleep Cohort Study, a population-based longitudinal study of sleep disor- ders. Participants underwent nocturnal polysomnography and reported on their sleep habits through questionnaires and sleep diaries. Following polysomnography, morning, fasted blood samples were evaluated for serum leptin and ghrelin (two key opposing hormones in appetite regulation), adiponectin, insulin, glucose, and lipid profile. Relationships among these measures, BMI, and sleep duration (habitual and immediately prior to blood sampling) were examined using multiple variable regressions with control for confounding factors. A U-shaped curvilinear association between sleep duration and BMI was observed. In persons sleeping less than 8 h (74.4% of the sample), increased BMI was proportional to decreased sleep. Short sleep was associated with low leptin (p for slope = 0.01), with a predicted 15.5% lower leptin for habitual sleep of 5 h versus 8 h, and high ghrelin (p for slope = 0.008), with a predicted 14.9% higher ghrelin for nocturnal (polysomnographic) sleep of 5 h versus 8 h, independent of BMI. Conclusion: Participants with short sleep had reduced leptin and ele- vated ghrelin. These differences in leptin and ghrelin are likely to increase appetite, possi- bly explaining the increased BMI observed with short sleep duration. In Western societies, where chronic sleep restriction is common and food is widely available, changes in appetite regulatory hormones with sleep curtailment may contribute to obesity. Methodology: All employees aged 30 to 60 yr of four state agencies in south central Wisconsin were mailed a survey on sleep habits, health, and demographics in 1989. Mailed surveys were repeated at 5-yr intervals. A stratified random sample of respondents was then recruited for an extensive overnight protocol including polysomnography at baseline. Collection of morning, fasted blood levels of leptin, insulin, ghrelin and adiponectin were added to the protocol in 1995. A 6-day diary of sleep duration was added as part of a protocol to assess daytime sleepiness after the initiation of the cohort study. Multiple regression was used to evaluate the relationship of age, sex, and BMI on hormones. Partial correlations adjusted for age, sex, and BMI were calculated for hormones, with and without control of other potential confounders. The relationships between hormones and sleep were evaluated using multiple linear regression after control for potential confounders including age, sex, BMI, SDB (sleep disordered breathing), and morningness tendencies. Scope of Work: To investigate the associations among sleep duration (acute and habitual), metabolic hor- mones, and BMI in the population-based Wisconsin Sleep Cohort Study. Two key oppos- ing hormones in appetite regulation, leptin and ghrelin, play a significant role in the inter- action between short sleep duration and high BMI. Leptin is an adipocyte-derived hormone that suppresses appetite. Ghrelin is predominantly a stomach-derived peptide that stimu- lates appetite. Other mediators of metabolism that may contribute include adiponectin and insulin. Adiponectin is a novel hormone secreted by adipocytes and is associated with insulin sensitivity. Sample Size: 1,024 participants in the overnight study and blood sample. 720 in the diary portion. Industry Sector: General population Major Limitations: Baseline response rate was 51%.

OCR for page 122
136 Findings Directly Related Driver Health (General) to HOS (include page references): "We found a significant U-shaped curvilinear relationship between average nightly sleep and BMI after adjustment for age and sex. The minimum BMI was predicted at 7.7 h of average nightly sleep. The most striking portion of the curve was for persons sleeping less than 8 h, where increased BMI was proportional to decreased sleep." (p. 4 of 11) In the multiple regression model, there was a significant increasing trend in leptin for aver- age nightly sleep duration. There was a significant decreasing trend in ghrelin with total sleep time. (Low leptin and elevated ghrelin are usually associated with increased appetite.) There was no significant correlation between sleep duration (acute or chronic) and serum adiponectin, insulin, and glucose. "[These findings] also represent the first demonstration of a correlation between peripheral hormone levels and both self-reported (questionnaire and diary data) and polysomno- graphically determined sleep amounts in a general population sample." (p. 5 of 11) "When controlling for BMI, we found no significant correlation between insulin, glucose, or adiponectin levels and various measures of sleep duration." (p. 7 of 11) Reviewer's Notes: Study shows association between sleep duration and obesity, and sleep duration and hor- mones which increase appetite. No association was found with sleep duration and glucose or insulin levels.

OCR for page 122
137 Reviewer: Susan Buchanan Complete Title: Working Long Hours. White J, Beswick J. United Kingdom Health and Safety Labora- tory. 2003. Abstract: n/a Methodology: Literature review. Literature searches were conducted by the HSE Information Centre search team. The team searched the following databases: OSH-ROM, RILOSH; HSELINE; CISDOC: NIOSHTIC2; Medline; Psychlit; EMED; and Healsafe. The key words used were: long working hours; working time; fatigue; health; safety; work-life balance; acci- dents; psychological effects; task; industry. Shiftwork was specifically omitted. In order to keep the review to a manageable size, it was decided to concentrate solely on articles relat- ing to long working hours, and not those relating to shiftwork, and on literature from the last 10 years. Articles from academic journals as well as articles from health and safety related and other journals were retrieved. The articles included in this review were mostly selected on the basis of their abstract. The findings of the review reflect these constraints. Scope of Work: To review the literature on the relationship between long working hours and fatigue, health and safety, and work-life balance outcomes. Sample Size: n/a Industry Sector: n/a Major Limitations: n/a Findings Directly Related Driver Health (General) to HOS (include page references): Several studies investigating `karoshi' in Japan were reviewed. Karoshi refers to a syn- drome of cardiovascular attacks attributable in part to the long-hours culture of the Japa- nese. Few other health effects were included in this write-up: one study assessing the effect of long hours on immunity and one showing higher rates of diabetes were mentioned. "There appears to be a link between working long hours and cardiovascular disorder but several factors (e.g., existing medical conditions or insufficient sleep) may mediate this link."(p. 20) "There appears to be evidence linking working long hours with poor lifestyle behaviors and other physical health problems, such as lowered immunity and diabetes mellitus." (p. 20) "From the available evidence, there is sufficient reason to be concerned about a possible link between long hours and physical health outcomes, especially for hours exceeding 48 to 50 per week. However, samples were not very diverse, as much research seems to focus on men in Japan." (p. 20) Reviewer's Notes: This literature review reinforces the notion that long work hours may contribute to risk of cardiovascular disease. However, other health effects of long hours were barely mentioned. Most of this extensive report was devoted to fatigue, performance, and lifestyle issues, not to health effects.

OCR for page 122
138 Reviewer: Peter Orris Complete Title: Diesel and Health in America: the Lingering Threat. Schneider, C.G., Hill, L.B., Clean Air Task Force, Boston, MA, February 2005. Abstract: The U.S. Environmental Protection Agency has issued regulations that will require dra- matic reductions in emissions from new diesel vehicles starting in 2007--but only the new ones. These regulations, to be phased in over the next quarter century, apply only to new engines. The lifespan of the average diesel vehicle is nearly 30 years. Many diesels are driven over a million miles. Because of this longevity, we will be left with the legacy of pollution from dirty diesel vehicles for decades to come. Pollution from dirty diesels on the road now can be dramatically reduced using a combination of cleaner fuels, retrofit emis- sion controls, rebuilt engines, engine repowerings, and accelerated purchase of new, cleaner vehicles. The Clean Air Task Force commissioned Abt Associates, to quantify the health impacts of fine particle air pollution from America's diesel fleet. Using this information, we were able to estimate the expected benefits--in lives saved--from an aggressive but fea- sible program to clean up dirty diesel buses, trucks, and heavy equipment across the United States. It then reviews the degree to which diesel vehicles increase the level of fine particle pollution in the air we breathe, and recommends reduction measures that will save thou- sands of lives each year. Methodology: Collected available environmental particulate data, reviewed the literature as to health effects, modeled the amount of exposure from the current diesel truck fleet in the United States and calculated the human and economic costs of not putting in available protective technologies across the board. Scope of Work: To review the relationship between diesel exhaust and health impacts on the population as a whole and estimate the human and economic costs of continued inaction with respect to utilizing available technology to reduce exposure. Sample Size: n/a Industry Sector: n/a Major Limitations: Modeling exercise based on partial data allowing debate as to the magnitude of the quanti- tative conclusions reached. Findings Directly Related Driver Health (General) to HOS (include page references): Reducing diesel fine particle emissions 50% by 2010, 75% by 2015, and 85% by 2020 would save nearly 100,000 lives between now and 2030. Fine particle pollution from diesels shortens the lives of nearly 21,000 people each year. This includes almost 3,000 early deaths from lung cancer. Tens of thousands of Americans suffer each year from asthma attacks (over 400,000), heart attacks (27,000), and respiratory problems associated with fine particles from diesel vehicles. These illnesses result in thousands of emergency room visits, hospi- talizations, and lost work days. Together with the toll of premature deaths, the health damages from diesel fine particles will total $139 billion in 2010. Nationally, diesel exhaust poses a cancer risk that is 7.5 times higher than the com- bined total cancer risk from all other air toxics. In the United States, the average lifetime nationwide cancer risk due to diesel exhaust is over 350 times greater than the level U.S. EPA considers to be "acceptable" (i.e., one cancer per million persons over 70 years). Residents from more than two-thirds of all U.S. counties face a cancer risk from diesel exhaust greater than 100 deaths per million population. People living in eleven urban

OCR for page 122
139 counties face diesel cancer risks greater than 1,000 in a million--one thousand times the level EPA says is acceptable. The risk of lung cancer from diesel exhaust for people living in urban areas is three times that for those living in rural areas. Reviewer's Notes: This literature review is consistent with the conclusion that increased weekly working hours and the probable concomitant increased exposure to diesel exhaust is likely to contribute to an increased risk of cancer. It is also consistent with the conclusion that this impact is likely mitigated by changes in cab and engine design currently incorporated in new vehicles.