Insomnia and Cardiovascular Disease in Nursing Professionals- A Study on Day and Night Workers

Disentangling the effects of insomnia and night work on cardiovascular diseases a study in nursing professionals A SilvaCosta1 RH Griep2 and L Rotenberg2 1Escola Nacional de Sau de Pu blica Fundac a o Oswaldo Cruz Fiocruz Rio de Janeiro RJ Brasil 2Laborato rio de Educac a o em Ambiente e Sau de Instituto Oswaldo Cruz Fiocruz Rio de Janeiro RJ Brasil Abstract Cardiovascular diseases CVDs are known to be associated with poor sleep quality in general populations but they have not been consistently associated with specific work schedules Studies of CVD generally do not simultaneously consider sleep and work schedules but that approach could help to disentangle their effects We investigated the association between insomnia and a selfreported physician diagnosis of CVD in day and night workers considering all sleep episodes during nocturnal and diurnal sleep A crosssectional study was conducted in 1307 female nursing professionals from 3 public hospitals using baseline data from the Health and Work in Nursing a Cohort Study Participants were divided into two groups i day workers with no previous experience in night shifts n281 and whose data on insomnia were related to nocturnal sleep and ii those who worked exclusively at night n340 and had data on both nocturnal and diurnal sleep episodes as they often sleep at daytime Multiple logistic regression analysis was performed Among day workers insomnia complaints increased the odds of CVD 279fold 95 CI101671 compared with workers who had no complaints Among night workers reports of insomnia during both nocturnal and diurnal sleep increased the odds of reported CVD 307fold 95 CI130724 Workers with insomnia had similar probabilities of reporting CVD regardless of their work schedule suggesting a relationship to insomnia and not to night work per se The results also highlighted the importance of including evaluation of all sleep episodes diurnal plus nocturnal sleep for night workers Key words Cardiovascular diseases Insomnia Night work Nurse Sleep Introduction The association between cardiovascular diseases CVDs and sleep complaints such as difficulty falling asleep sleep maintenance or duration is well documented in general populations 12 Myocardial infarction coronary heart disease and stroke are related to sleep character istics in the general population as shown by epidemiolog ical investigations of insomnia 13 and sleep duration 4 CVDs are also thought to be associated with shift work 59 because of circadian stress caused by i psychosocial mechanisms related to work stress workfamily conflicts and the difficulty of recovering after work ii physiological mechanisms that influence inflammation blood clotting blood pressure and activation of the autonomic nervous system and hypothalamicpituitaryadrenal HPA axis and iii behavioral factors such as physical inactivity weight gain nutritional changes smoking and sleep duration and quality 10 All of these pathways have been linked directly or indirectly to sleep disturbances 1114 For instance a review of the association between insomnia and CVD shows that any deterioration in sleep quality or quantity may be associated with increases in nocturnal blood pressure and heart rate Inflammation was proposed as a possible explanation for this association because sleep loss is associated with increased cellular inflammatory signaling 1 Although the relationships between CVD and sleep complaints are well known in general populations the influence of work schedules has not been widely evaluated In this context a specific characteristic of night workers is that they often sleep during the day Therefore the analysis of their sleep should include day sleep not only because that is when they sleep but also because diurnal sleep corresponds to a chronobiological challenge with possible health repercussions 15 Studies of CVD that simultaneously investigate sleep complaints and work schedules could help to disentangle their effects that is determine whether the CVDs are related to night work per se or whether the relationship is dependent on sleep complaints The aim of this study was Correspondence A SilvaCosta alinecosiocfiocruzbr Received March 13 2014 Accepted July 22 2014 First published online November 21 2014 Brazilian Journal of Medical and Biological Research 2015 482 120127 httpdxdoiorg1015901414431X20143965 ISSN 1414431X Braz J Med Biol Res 482 2015 wwwbjournalcombr to investigate the association between complaints of insomnia and selfreported physician diagnosis of CVD in day and nightshift nursing workers considering all sleep episodes Subjects and Methods This crosssectional study was conducted in nursing professionals ie nursing aidesassistants and registered nurses from 3 public hospitals in Rio de Janeiro Brazil N1509 Regarding the tasks carried out by nursing workers nursing aides and assistants perform activities involving participation in nursing help hygiene care and patient comfort According to Brazilian legislation nursing aides and assistants can carry out their activities only with orientation and supervision provided by professional nurses Nurses perform administrative functions manage personnel and procedures and care for seriously ill patients including those whose condition requires knowl edge of its scientific basis performance of more complex procedures or making immediate decisions All nursing workers registered nurses nursing aides assistants who provided patient care were invited to participate Only female workers n1307 were included in the present analysis because of sex differences in sleep complaints 16 The procedures used to contact workers complied with ethical guidelines for conducting research with human subjects as follows The study was briefly explained to participants they were informed that involvement was completely voluntary and that they could withdraw at any time with no negative ramifications All participants signed the consent forms The project was approved by the ethics committees of the Oswaldo Cruz Foundation and the participating hospitals Data were collected using a comprehensive ques tionnaire examining workhealth relations among nursing personnel Respondents were asked to provide informa tion about their sociodemographic characteristics physi cal and mental health symptoms lifestyles and management of time spent in nonprofessional activities age marital status education degree monthly income smoking physical activity body mass index sleep complaints selfreport of physician diagnosis of CVD domestic work hours professional work hours profes sional category time spent performing nursing activities and number of working nights The instrument also included scales evaluating psychosocial factors at work demandcontrol and effortreward imbalance The ques tionnaire comprised two parts to accommodate the complexity of defining work schedules for nursing profes sionals due to the large number of workers holding two jobs in Brazilian hospitals 1718 and to changes in individual work schedules 19 For the first part trained interviewers recorded information provided by partici pants including insomnia complaints to increase the accuracy of the data The second part which included the selfreported physician diagnosis of CVDs was self administered after the interviewers explained the purpose of the research and provided instructions on how to complete the questionnaire 1718 Variable definitions and classification Work schedules To exclude the possible influence of past experience with night work on insomnia complaints 18 all analyses of day workers only included workers with no previous nightwork experience This group was compared with those who worked only at night at the time of data collection This procedure was designed to allow the comparison of homogeneous groups based on current work schedules day or night only regardless of the number of jobs held Interviewers asked the question Do you regularly at least once a week4 times a month work night shifts in nursing assistance somewhere to classify participants work schedules at all jobs The interviewers were instructed to define regularly as at least once a week when asking the question and as at least 4 times a month for participants who considered their weekly schedules to be highly variable The format of this question was based on the previously observed high variability of an individual workers number of working nights which may lead respondents to have difficulty defining the usual number of working nights 17 Participants who answered yes were considered current night workers which is similar to the classification used by Marquie and Foret 20 Those who answered no were classified as day workers Day workers previous experience with night work was defined using the question Have you ever worked at night Possible answers were i yes regularly once a week ii yes regularly 2 or 3 times a week iii yes regularly 4 or more times a week iv yes rarely v yes occasionally and vi no Participants who responded that they had regularly worked from 1 to 4 or more times per week were classified as former night workers Those who responded that they had rarely occasionally or never worked at night were classified as day workers with no nightwork experience Previous nightwork experience varied from less than 1 year to 26 years Former night workers n400 were excluded from the analysis as were participants who worked during the day at one job and at night at the second job n285 The study sample comprised data from nurses who worked during the day and had no previous experience in night work n281 and those who worked only at night at the time of data collection n340 There was one participant with missing data Selfreported physician diagnosis of CVD CVDs were classified based on respondents selfreports of a medical diagnosis of hypertension coronary disease myocardial infarction or heart failure as defined by the World Health Organization WHO 21 A report of at least one of these Insomnia night work and cardiovascular diseases in nurses 121 wwwbjournalcombr Braz J Med Biol Res 482 2015 diseases diagnosed by a doctor was the criteria used to classify participants As the question for CVD evaluation was the same for day and night workers and for workers with and without insomnia complaints we do not expect that differences between the groups resulted from the way this information was obtained Insomnia complaints All workers were asked about insomnia using the following questions In relation to your sleep during the night during the last 4 weeks at home how often did you i have difficulty falling asleep ii wake up and have difficulty going to sleep again and iii wake up before the desired time and not manage to sleep again For all questions the possible responses were never rarelysometimes ie no sleep complaint and almost alwaysalways ie sleep complaint Respondents who reported any of the described sleep problems were assigned to the insomnia group 2224 Thus day workers were evaluated for nighttime sleep insomnia Moreover considering that night workers often sleep during the day the instrument for collecting data included questions about insomnia complaints relating to daytime sleep The night workers thus answered the following questions In relation to your sleep during the day before or after a night shift during the last 4 weeks how often did you with the same questions and response alterna tives used for insomnia complaints related to nocturnal sleep Thus while day workers were evaluated for insomnia related to nocturnal sleep night workers were evaluated for the presence or absence of insomnia episodes during sleep i at night ii during the day and iii both nighttime and daytime The kappa statistic was used to assess the reliability of sleep variables The kappa value for insomnia complaints among day workers was 063 95CI036 089 indicating substantial stability For night workers kappa values for nocturnal and diurnal insomnia com plaints were 060 95CI038082 and 050 95CI022078 indicating substantial and moderate agreement respectively 25 Data analysis Descriptive analyses of sociodemographic lifestyle and workrelated variables were performed using the chi square or MannWhitney test P005 Tests were used to screen potential confounders including age race smoking and alcohol habits body mass index physical activity marital status monthly family income education level professional and domestic work hours professional category time spent on nursing activities number of jobs demandcontrol and effortreward imbalance effort reward cutoff was the third tertile Variables showing at least minimal association P020 with the outcome and the exposure and variables described in the literature as potential confounders were selected for inclusion in multiple logistic regression models The logistic regres sion was used to test the association between insomnia complaints and selfreporting of physician diagnosis of CVDs All analyses were performed separately for day and night workers with results reported as odds ratios OR and 95CI The SPSS software version 180 SPSS Inc USA was used for data analysis Results Most workers were nursing aidesassistants 789 Professional nurses were younger than the nursing aides assistants 354 vs 382 years old P0032 and had a higher income US49880 vs US28060 P0001 The professional work hours P0278 domestic work hours P0828 number of jobs P0721 smoking habits P0125 and marital situation P0140 of profes sional nurses and nursing aidesassistants were not significantly different Neither insomnia complaints nor CVDs were significantly different between professional nurses and nursing aidesassistants The proportions of professional nurses and nursing aidesassistants did not differ between groups therefore the data for all workers within each group were combined for all analyses The mean SD age of workers was 376132 years The average durations of nursing work were 107114 and 135112 years and the average numbers of professional work hours worked per week were 405121 and 451170 for day and night workers respectively The prevalence of selfreported physician diagnosis of CVD was 18 among day workers and 21 among night workers Nocturnal insomnia complaints were reported by 23 and 24 of day and night workers respectively The prevalence of diurnal sleeprelated insomnia complaints was 35 among night workers 13 of whom reported both diurnal and nocturnal sleeprelated insomnia complaints Table 1 shows that participants who reported CVDs were older worked more hours per week combined professional and domestic activities and were more often overweight or obese than those who did not reported having a diagnosis of CVD Table 2 describes the sociodemographic and work characteristics of nursing workers with insomnia com plaints Among the day workers 27 reported CVDs 35 of night workers with both day and night insomnia complaints reported CVDs and 535 were classified in the group exposed to effortreward imbalance Night workers with complaints of day and night insomnia worked longer domestic hours than did those without complaints of day and night insomnia 245 and 178 hours respectively The association between insomnia and selfreported CVD diagnosis was statistically significant after adjusting for sociodemographic lifestyle and workrelated vari ables Among day workers nocturnal insomnia com plaints increased the chances of selfreported physician diagnosis of CVDs 279fold 95 CI101671 com pared with those with no insomnia complaints Among 122 A SilvaCosta et al Braz J Med Biol Res 482 2015 wwwbjournalcombr night workers diurnal and nocturnal insomnia complaints increased the odds of selfreported physician diagnosis of CVDs OR307 95 CI130724 Table 3 Discussion In the present study insomnia complaints were associated with selfreported physician diagnosis of CVDs among day workers The same result was observed for night workers provided that both diurnal and nocturnal sleep episodes were considered It is noteworthy that these associations were adjusted for several confounding factors including psychosocial aspects known to be related to CVD and insomnia The probability of selfreporting a physician diagnosis of CVD was similar for day and night workers with insomnia suggesting that this was associated with insomnia and not to night work per se This result helps to disentangle the relationships among insomnia night work and CVD Prospective epidemiological studies conducted in the general population have revealed associations between insomnia and CVD Chien 26 found that the risk of developing CVD was 178times greater in individuals who reported insomnia than in those who did not Another recent study showed that complaints of difficulty falling asleep and maintaining sleep were associated with increases of 45 and 30 respectively in the risk of acute myocardial infarction 27 Phillips and Mannino 28 observed that the risk of developing CVD was 50 greater in participants who had difficulty falling asleep awoke repeatedly and woke feeling tired than in those without such complaints A review of insomnia and CVDs 1 pointed out that resting heart rates tend to be slightly elevated in individuals with insomnia which can increase cardiovascular risk Night shifts and rotating shifts have been associated with several chronic diseases including CVD 8 Nevertheless the prevalence of CVD did not differ in day and night workers in the present study Night workers are exposed both to cardiovascular risks common to the general population and to circadian misalignment due to the negative influence of night work on the cardiovascular system 10 Also a higher prevalence of insomnia com plaints among night workers compared to day workers would be expected because of the negative effect of night work on sleep 2931 However in this study day and night workers did not differ with regard to nightsleep difficulties confirming previous data gathered from nur sing professionals 32 The similarity of nightsleep insomnia complaints in night and dayshift workers is Table 1 Sociodemographics life style and work characteristics among nursing workers according to the prevalence of selfreported physician diagnosis of cardiovascular diseases CVD Selfreported physician diagnosis of CVD No n489 Yes n121 Total Age years 348 124 491 992 376 132 Monthly family income US 34430 22590 32380 24710 34010 23130 Weekly domestic work hours 153 159 258 181 173 168 Weekly professional work hours 438 154 402 137 438 151 School education Fundamentalhigh school 401 633 447 College education 599 367 553 Overweightobese 374 655 431 Smoking habits 106 157 116 Engaged in 2 or 3 jobs 184 165 181 Marital status Single 446 231 403 Marriedliving with partner 423 471 433 Divorcedseparatedwidowed 131 298 164 Professional category Registered nurses 225 157 211 Nurse assistantsaides 775 843 789 Time on nursing activities years 99 108 216 89 123 114 Number of working nights per 2week span 59 21 58 22 59 21 Effort reward imbalance 319 331 321 High demand and low control 193 221 198 Data are reported as meansSD or otherwise indicated P005 statistically significant association chisquare or MannWhitney test Insomnia night work and cardiovascular diseases in nurses 123 wwwbjournalcombr Braz J Med Biol Res 482 2015 Table 2 Sociodemographics work characteristics and prevalence of selfreported physician diagnosis of cardiovascular diseases among nursing workers according to insomnia complaints Insomnia complaints Day workers Night workers Night sleep Night sleep Day sleep Day and night sleep No n217 Yes n64 No n256 Yes n84 No n140 Yes n76 No n293 Yes n46 Age years 369 137 374 133 375 130 395 126 362 122 359 116 381 131 376 117 Monthly family income US 34380 242 32880 221 32140 205 28880 209 31100 22220 31730 182 31280 208 31570 198 Weekly domestic work hours 149 132 177 161 177 187 218 189 156 162 234 203 178 189 245 176 Weekly professional work hours 407 116 396 139 450 173 448 161 470 170 468 167 446 169 476 172 School education Fundamentalhigh school 54 59 36 36 38 33 37 33 College education 46 41 64 64 62 67 63 67 Overweightobese 38 41 47 47 48 45 46 49 Smoking habits 15 19 12 20 10 14 14 15 Engaged in 2 or 3 jobs 124 172 20 26 27 21 21 26 Marital status Single 41 41 41 31 44 29 40 28 Marriedliving with partner 44 47 42 49 44 46 43 46 Divorcedseparatedwidowed 15 12 17 20 12 25 17 26 Professional category Registered nurses 24 20 19 19 21 22 18 26 Nurse assistantsaides 76 80 81 81 79 78 82 74 Time on nursing activities years 105 114 115 116 129 118 149 105 127 115 113 102 133 114 138 102 Number of working nights per 2week span 59 21 60 20 61 22 59 22 59 19 61 24 Cardiovascular diseases 16 27 19 29 17 25 19 35 Effort reward imbalance 323 397 265 506 209 458 291 535 High demand and low control 166 197 143 256 88 261 157 256 Data are reported as meansSD or otherwise indicated P005 statistically significant association chisquare or MannWhitney test 124 A SilvaCosta et al Braz J Med Biol Res 482 2015 wwwbjournalcombr consistent with the findings of Akerstedt et al 33 who conducted a questionnairebased survey of a representa tive sample of the Swedish population They reported that nightshift workers did not consider shift work as a major source of sleep disturbances and observed that their complaint levels bear no resemblance to those seen in insomniac patients The authors argued that shift work ers might not consider their sleep to be disturbed and that sleep disturbances may partly be overlooked andor considered part of the job 33 In their study the similarity of nocturnalsleep insomnia complaints made by day and nightshift workers may be explained by the exclusive analysis of night sleep which is the most common study design Among night workers the OR of selfreporting a physician diagnosis of CVD related to nocturnal sleep complaints OR181 was much smaller than that for both nocturnal and diurnal sleep OR279 The findings of this study reveal the importance of not restricting the analyses of insomnia to nocturnal sleep in the case of night workers Moreover in that group the higher prevalence of day compared with nightsleep insomnia complaints 35 vs 24 shows that the exclusive analysis of complaints referring to night sleep does not capture the entire impact of work schedules and highlights the relevance of considering all sleep episodes This importance stems from the fact that night workers often sleep during the day and are also exposed to difficulties of a chronobiological nature with health implications 15 A potential biological explanation for the association of insomnia and sleep debt with cardiovascular risks 34 is related to an association of insomnia with both glucose metabolism disorders and high blood pressure This relationship cannot be described as a linear cascade rather it is a complex multifactorial process involving a neuroendocrinemetabolic network 35 Several studies have shown that sleep deprivation increases sympathetic nervous system activity leading to increased blood pressure and heart rate 3637 Inflammation is also pointed out as a possible explanation for this association 1 MeierEwert 38 reported that inadequate sleep might increase the risk of CVD in apparently healthy individuals due to the activation of inflammatory processes which could contribute to the association between sleep com plaints and cardiovascular morbidity Furthermore the combined effects of overtime work and insufficient sleep may critically increase nervous system activity potentially inducing acute myocardial infarction 39 Several limitations of this study should be considered First it did not examine the direction of causality in the association between sleep problems and cardiovascular outcomes a reverse causality is possible Barone and MennaBarreto 35 described the interaction of diabetes which is strongly associated with cardiovascular risk and sleep as a vicious cycle Second although the analyses performed in this study were adjusted for potential confounding factors the possibility of residual effects or those of uncontrolled variables cannot be excluded Third because CVDs were evaluated on the basis of self reported medical diagnoses the data were subject to reporting bias However this bias was not expected to differ between day and night workers Metabolic diseases immune system disorders and depression all of which could influence the relations between the studied expo sure and the outcome were not investigated Also the prevalence of both CVD and insomnia complaints observed in this study may have been influenced by the healthy worker effect in which there is a selection of those more tolerant to work and who tend to be healthier 15 Finally the data collection instrument used in this Table 3 Association between insomnia complaints and selfreported physician diagnosis of cardiovascular diseases among nursing professionals Work schedule Insomnia complaint Selfreported physician diagnosis of CVD Model 1 Crude OR 95CI Model 2 Adjusted OR 95CI Model 3 Adjusted OR 95CI Day work No complaint concerning nocturnal sleep 1 1 1 Complaint concerning nocturnal sleep 233 128461 267 104688 279 101671 Night work No complaint concerning both diurnal and nocturnal sleep 1 1 1 Complaint concerning both diurnal and nocturnal sleep 247 124492 337 146779 307 130724 No complaint concerning nocturnal sleep 1 1 1 Complaint concerning nocturnal sleep 184 102329 205 101410 181 088375 No complaint concerning diurnal sleep 1 1 1 Complaint concerning diurnal sleep 182 088376 235 097568 201 081504 Insomnia complaints refer to nocturnal andor diurnal sleep episodes Model 1 unadjusted model Model 2 analysis adjusted for age race smoking habits weekly domestic work hours and body mass index Model 3 analysis adjusted for model 2 plus work factors weekly professional work hours and effort reward imbalance CVD cardiovascular diseases Insomnia night work and cardiovascular diseases in nurses 125 wwwbjournalcombr Braz J Med Biol Res 482 2015 study included workrelated factors questions about professional work hours and two psychosocial scales demandcontrol and effortreward imbalance As argued by McNeely 40 studies that investigate the health effects of nurses work typically measure only physical or psychological demands resulting in underestimations In the present study other organizational and psychoso cial aspects that were not considered may have influ enced the results Studies of the relationship between shift work and cardiovascular risk face the difficulty of accounting for heterogeneity of individual work schedules and the number of working nights per week 9 In the present study night workers worked exclusively at night and day workers had no previous night work experience This distinction reduced heterogeneity among workers and constitutes a study strength In sum this study has two main contributions First it demonstrates the relevance of evaluating sleep according to work shift and sleep pattern nocturnal andor diurnal episodes which has not been previously reported in the literature Second workers with insomnia have similar chances of reporting CVD regardless of their work schedule thus suggesting that this is related to insomnia and not to night work per se Finally the study indicates that sleep disturbance is a public health problem that deserves to be better understood and addressed by both policymakers and workers themselves As insomnia is the most common sleep complaint our findings highlight the importance of considering all sleep episodes on the investigation and treatment of insomnia in patients with CVD Acknowledgments Research supported by CNPq and FAPERJ L Rotenberg and RH Griep are Irving Selikkoff International Fellows of the Mount Sinai School of Medicine ITREOH Program Their work was supported in part by Grant 1 D43 TW00640 from the Fogarty International Center of the National Institutes of Health References 1 Spiegelhalder K Scholtes C Riemann D The association between insomnia and cardiovascular diseases Nat Sci Sleep 2010 2 7178 doi 102147NSSS7471 2 Ohayon MM Observation of the natural evolution of insomnia in the American general population cohort Sleep Med Clin 2009 4 8792 doi 101016jjsmc200812002 3 Sofi F Cesari F Casini A Macchi C Abbate R Gensini GF Insomnia and risk of cardiovascular disease a meta analysis Eur J Prev Cardiol 2014 21 5764 doi 1011772047487312460020 4 Meisinger C Heier M Lowel H Schneider A Doring A Sleep duration and sleep complaints and risk of myocardial infarction in middleaged men and women from the general population the MONICAKORA Augsburg cohort study Sleep 2007 30 11211127 5 Knutsson A Health disorders of shift workers Occup Med 2003 53 103108 doi 101093occmedkqg048 6 Fujino Y Iso H Tamakoshi A Inaba Y Koizumi A Kubo T et al A prospective cohort study of shift work and risk of ischemic heart disease in Japanese male workers Am J Epidemiol 2006 164 128135 doi 101093ajekwj185 7 Tuchsen F Hannerz H Burr H A 12 year prospective study of circulatory disease among Danish shift workers Occup Environ Med 2006 63 451455 doi 101136oem 2006026716 8 Wang XS Armstrong ME Cairns BJ Key TJ Travis RC Shift work and chronic disease the epidemiological evidence Occup Med 2011 61 7889 doi 101093occmedkqr001 9 Leclerc A Shiftwork and cardiovascular disease Eur J Epidemiol 2010 25 285286 doi 101007s10654010 94562 10 Puttonen S Harma M Hublin C Shift work and cardiovas cular disease pathways from circadian stress to morbidity Scand J Work Environ Health 2010 36 96108 doi 105271sjweh2894 11 Kivimaki M Virtanen M Elovainio M Kouvonen A Vaananen A Vahtera J Work stress in the etiology of coronary heart disease a metaanalysis Scand J Work Environ Health 2006 32 431442 doi 105271sjweh1049 12 Eller NH Netterstrom B Gyntelberg F Kristensen TS Nielsen F Steptoe A et al Workrelated psychosocial factors and the development of ischemic heart disease a systematic review Cardiol Rev 2009 17 8397 doi 101097CRD0b013e318198c8e9 13 Boggild H Knutsson A Shift work risk factors and cardiovascular disease Scand J Work Environ Health 1999 25 8599 doi 105271sjweh410 14 Spiegel K Tasali E Penev P Van Cauter E Brief communication Sleep curtailment in healthy young men is associated with decreased leptin levels elevated ghrelin levels and increased hunger and appetite Ann Intern Med 2004 141 846850 doi 1073260003481914111 20041207000008 15 Costa G Sau de e trabalho em turnos e noturno In Fischer FM Moreno CRC Rotenberg L Editors Trabalho em turnos e noturno na sociedade 24 horas Sa o Paulo Atheneu 2004 16 Krishnan V Collop NA Gender differences in sleep disorders Curr Opin Pulm Med 2006 12 383389 doi 10109701mcp0000245705694406a 17 Rotenberg L Griep RH Fischer FM Fonseca MJ Landsbergis P Working at night and work ability among nursing personnel when precarious employment makes the difference Int Arch Occup Environ Health 2009 82 877 885 doi 101007s0042000803834 18 Rotenberg L SilvaCosta A Diniz TB Griep RH Longterm deleterious effects of night work on sleep Sleep Sci 2011 4 1320 126 A SilvaCosta et al Braz J Med Biol Res 482 2015 wwwbjournalcombr 19 RibeiroSilva F Rotenberg L Soares RE Pessanha J Ferreira FL Oliveira P et al Sleep on the job partially compensates for sleep loss in nightshift nurses Chronobiol Int 2006 23 13891399 doi 10108007420520601091931 20 Marquie JC Foret J Sleep age and shiftwork experience J Sleep Res 1999 8 297304 doi 101046j1365 2869199900170x 21 World Health Organization WHO Cardiovascular dis eases httpwwwwhointtopicscardiovasculardiseases enindexhtml 22 Ohayon MM Epidemiology of insomnia what we know and what we still need to learn Sleep Med Rev 2002 6 97111 doi 101053smrv20020186 23 Pires ML BeneditoSilva AA Mello MT Del Giglio S Pompeia C Tufik S Sleep habits and complaints of adults in the city of Sao Paulo Brazil in 1987 and 1995 Braz J Med Biol Res 2007 40 15051515 doi 101590S0100879X 2006005000170 24 Robaiana JR Lopes CS Rotenberg L Faerstein E Fischer FM Moreno CRC et al Stressful life events and insomnia complaints among nursing assistants from a university hospital in Rio de Janeiro The ProSaude Study Rev Bras Epidemiol 2009 12 501509 doi 101590S1415 790X2009000300018 25 Landis JR Koch GG The measurement of observer agreement for categorical data Biometrics 1977 33 159 174 doi 1023072529310 26 Chien KL Chen PC Hsu HC Su TC Sung FC Chen MF et al Habitual sleep duration and insomnia and the risk of cardiovascular events and allcause death report from a communitybased cohort Sleep 2010 33 177184 27 Laugsand LE Vatten LJ Platou C Janszky I Insomnia and the risk of acute myocardial infarction a population study Circulation 2011 124 20732081 doi 101161CIRCULA TIONAHA111025858 28 Phillips B Mannino DM Do insomnia complaints cause hypertension or cardiovascular disease J Clin Sleep Med 2007 3 489494 29 Niedhammer I Lert F Marne MJ Effects of shift work on sleep among French nurses A longitudinal study J Occup Med 1994 36 667674 30 Pires ML Teixeira CW Esteves AM Bittencourt LR Silva RS Santos RF et al Sleep ageing and night work Braz J Med Biol Res 2009 42 839843 doi 101590S0100 879X2009005000011 31 Rajaratnam SM Howard ME Grunstein RR Sleep loss and circadian disruption in shift work health burden and management Med J Aust 2013 199 S11S15 doi 105694mja1310561 32 Portela LF Rotenberg L Waissmann W Selfreported health and sleep complaints among nursing personnel working under 12 h night and day shifts Chronobiol Int 2004 21 859870 doi 101081CBI200038513 33 Akerstedt T Ingre M Broman JE Kecklund G Disturbed sleep in shift workers day workers and insomniacs Chronobiol Int 2008 25 333348 doi 101080 07420520802113922 34 Nilsson PM Nilsson JA Hedblad B Berglund G Sleep disturbance in association with elevated pulse rate for prediction of mortality consequences of mental strain J Intern Med 2001 250 521529 doi 101046j1365 2796200100913x 35 Barone MT MennaBarreto L Diabetes and sleep a complex causeandeffect relationship Diabetes Res Clin Pract 2011 91 129137 doi 101016jdiabres201007011 36 Lusardi P Zoppi A Preti P Pesce RM Piazza E Fogari R Effects of insufficient sleep on blood pressure in hyperten sive patients a 24h study Am J Hypertens 1999 12 63 68 doi 101016S0895706198002003 37 Tochikubo O Ikeda A Miyajima E Ishii M Effects of insufficient sleep on blood pressure monitored by a new multibiomedical recorder Hypertension 1996 27 1318 1324 doi 10116101HYP2761318 38 MeierEwert HK Ridker PM Rifai N Regan MM Price NJ Dinges DF et al Effect of sleep loss on Creactive protein an inflammatory marker of cardiovascular risk J Am Coll Cardiol 2004 43 678683 doi 101016jjacc200307050 39 Liu Y Tanaka H Overtime work insufficient sleep and risk of nonfatal acute myocardial infarction in Japanese men Occup Environ Med 2002 59 447451 doi 101136 oem597447 40 McNeely E The consequences of job stress for nurses health time for a checkup Nurs Outlook 2005 53 291 299 doi 101016joutlook200510001 Insomnia night work and cardiovascular diseases in nurses 127 wwwbjournalcombr Braz J Med Biol Res 482 2015