IRCCS Maggiore Hospital, Mangiagalli and Regina Elena Foundation. Milano. Italy. Stockholm. Sweden

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1 This article was downloaded by:[universita Studi di Milano] [Universita Studi di Milano] On: 12 July 2007 Access Details: [subscription number ] Publisher: Informa Healthcare Informa Ltd Registered in England and Wales Registered Number: Registered office: Mortimer House, Mortimer Street, London W1T 3JH, UK Chronobiology International The Journal of Biological and Medical Rhythm Research Publication details, including instructions for authors and subscription information: Influence of Flexibility and Variability of Working Hours on Health and Well-Being Giovanni Costa a ; Samantha Sartori a ; Torbjorn?kerstedt b a Department of Occupational and Environmental Health, University of Milano and IRCCS Maggiore Hospital, Mangiagalli and Regina Elena Foundation. Milano. Italy b IPM and Division of Psychosocial Factors and Health, Karolinska Institute. Stockholm. Sweden Online Publication Date: 01 October 2006 To cite this Article: Costa, Giovanni, Sartori, Samantha and?kerstedt, Torbjorn, (2006) 'Influence of Flexibility and Variability of Working Hours on Health and Well-Being ', Chronobiology International, 23:6, To link to this article: DOI: / URL: PLEASE SCROLL DOWN FOR ARTICLE Full terms and conditions of use: This article maybe used for research, teaching and private study purposes. Any substantial or systematic reproduction, re-distribution, re-selling, loan or sub-licensing, systematic supply or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material. Taylor and Francis 2007

2 Chronobiology International, 23(6): , (2006) Copyright # Informa Healthcare ISSN print/ online DOI: / INFLUENCE OF FLEXIBILITY AND VARIABILITY OF WORKING HOURS ON HEALTH AND WELL-BEING Giovanni Costa, 1 Samantha Sartori, 1 and Torbjorn A kerstedt 2 1 Department of Occupational and Environmental Health, University of Milano and IRCCS Maggiore Hospital, Mangiagalli and Regina Elena Foundation, Milano, Italy 2 IPM and Division of Psychosocial Factors and Health, Karolinska Institute, Stockholm, Sweden Flexible working hours can have several meanings and can be arranged in a number of ways to suit the worker and/or employer. Two aspects of flexible arrangement of working hours were considered: one more subjected to company control and decision (variability) and one more connected to individual discretion and autonomy ( flexibility). The aim of the study was to analyze these two dimensions in relation to health and wellbeing, taking into consideration the interaction with some relevant background variables related to demographics plus working and social conditions. The dataset of the Third European Survey on working conditions, conducted in 2000 and involving 21,505 workers, was used. Nineteen health disorders and four psycho-social conditions were tested by means of multiple logistic regression analysis, in which mutually adjusted odds ratios were calculated for age, gender, marital status, number of children, occupation, mode of employment, shift work, night work, time pressure, mental and physical workload, job satisfaction, and participation in work organization. The flexibility and variability of working hours appeared inversely related to health and psycho-social well-being: the most favorable effects were associated with higher flexibility and lower variability. The analysis of the interactions with the twelve intervening variables showed that physical work, age, and flexibility are the three most important factors affecting health and well-being. Flexibility resulted as the most important factor to influence work satisfaction; the second to affect family and social commitment and the ability to do the same job when 60 years old, as well as trauma, overall fatigue, irritability, and headache; and the third to influence heart disease, stomachache, anxiety, injury, and the feeling that health being at risk because of work. Variability was the third most important factor influencing family and social commitments. Moreover, shift and night work confirmed to have a significant This paper was presented at the 17th International Symposium on Shiftwork and Working Time, September 18-22, 2005, Hoofddorp, The Netherlands. Address correspondence to Prof. Giovanni Costa, Department of Occupational and Environmental Health, University of Milano and IRCCS Maggiore Hospital, Mangiagalli and Regina Elena Foundation, Clinica del Lavoro L. Devoto, Via san Barnaba 8, 20122, Milano, Italy. Tel.: þ ; Fax: þ giovanni.costa@unimi.it 1125

3 1126 influence on sleep, digestive and cardiovascular troubles, as well and health and safety at work. Time pressure also showed a relevant influence, both on individual stress and social life. Therefore, suitable arrangements of flexible working time, aimed at supporting workers coping strategies, appear to have a clear beneficial effect on worker health and well-being, with positive consequences also at the company and social level, as evidenced by the higher feeling to be able to work until 60 years of age. Keywords Flexible working hours, Flexibility, Variability, Health, Psycho-social wellbeing INTRODUCTION G. Costa et al. Flexible working times have been advocated for some time and now appear to be one of the best ways to cope with the demands of the modern working life (Baum and Young, 1973; Golden and Figart, 2000; Hörning et al., 1995). The increasing interest in temporal flexibility (Goudswaard and de Nanteuil, 2000) is due, on the one hand, to policies related to working time reduction and employment, and, on the other, to a progressive transfer of attention from the quantitative to the qualitative aspects of work and social activities. There are large differences on conceptualization and approaches to flexible working hours in relation to cultural, historical, and socio-economical factors, but, above all, there are different points of view between employers and employees. For the former, they are tools for a prompt adjustment of production and service systems to market demands and technological innovations; for the latter, they are important tools to improve working and social life, increasing employment and time sovereignty. That leads, on the one hand, to changing operational times according to varying customer and service times (e.g., shift and night work, split shifts, weekend work, seasonal work), and, on the other hand, to a reduction of individual working hours and an increased autonomy in working-time regulation (e.g., part-time work, shortened work week, self-determined start and end times, and bank of hours). Work-life balance is a concept with increasing importance in ergonomics, which has to take into account both diversities among groups and individuals (e.g., older workers, women, family responsibilities, income levels, and expertise) and their social interactions (e.g., consumer s role, participation in social groups, and leisure activities). Undoubtedly, flexible work hours may result in changes in total working time, work shift duration, amount of night work, and greater variability in working time schemes, which may have effects on family, social life, and health. It can be argued that, in general, the greater the individual-based flexibility, the better the health and work satisfaction; whereas, company-based flexibility might have a more negative interference. However, due to their different possible combinations, the expected effects on health and working conditions cannot be assessed a priori, but

4 they have to be carefully analyzed, taking into account several intervening personal and social factors. Moreover, the result of their interactions may depend (and largely differ) on such individual factors as the time of occurrence in the worker s life, their duration, etc. In a previous analysis of the Third EU Survey on working conditions (Costa et al., 2004), the authors tried to evaluate possible relations between different flexible working hours and health. An index of arrangement of working hours more subjected to company control and decision was defined as variability, and an index more related to individual discretion and autonomy was defined as flexibility. In general, the individualoriented flexibility was associated with better health conditions than the company-based variability. The aim of the present study was to analyze in greater depth the relation between these two dimensions of working time organization in relation to health and well-being, considering the interaction with some relevant background variables related to demographics and working and social conditions. METHODS Influence of Working Hours on Health and Well-Being 1127 The dataset of the Third European Survey on working conditions done in 15 European countries (Paoli and Merllié, 2001) involved 21,505 people, including self-employed (3,595) and employed (17,910) workers, both men (11,815) and women (9,690), standardized by age, work sector, and country. The questionnaire that was used to acquire the dataset was composed of about 70 questions concerning demographics, work sector, mode of employment, working hours, work environment, income level, work risk factors, and health. The research was conducted according to ethical guidelines of the journal (Touitou et al., 2004). In order to explore the possible influence of some aspects of flexible working hours, keeping in mind that no direct questions on flexible working hours or direct indices of flexibility were included, two new variables were created, derived from some questions of the survey. These new variables were named as follows: Variability. Variability is based on responses to the questions about having or not having to work the same number of hours every day, the same number of days every week, and with fixed starting and finishing times. It is considered to be an index of more or less variable working times, entailing a form of flexible arrangement of working hours more subjected to company control and decision. Working hours were considered variable if people replied no to all the three questions, partially variable if they replied no to one or two questions, and fixed if they replied yes to all the three questions.

5 1128 G. Costa et al. Flexibility. Flexibility is based on responses to the questions about taking a break when one wished, deciding when to take holidays or days off, and influencing one s own working hours. It is considered to be an index of a working hours arrangement more connected to individual discretion and autonomy. Working hours were considered flexible if people replied yes to all three items, partially flexible if they replied yes to one or two items, and rigid if they replied no to all three items. The influence of variability and flexibility were tested on the most important health and well-being outcomes by means of multiple logistic regression analysis, taking into account the most important background factors encompassing personal, social, and work domains, such as: gender: women vs. men; age: 25 39, 40 54, over 54 vs. under 25 years of age; marital status: unmarried, separated/divorced vs. married; number of children: 1 2 children, more than 2 children vs. none; mode of employment: employed vs. self-employed; shift work vs. day work; night work vs. day work; time pressure: high vs. low; mental load: high vs. low; heavy physical workload: high vs. low; social environment: no participation in work organization vs. participation; job: clerks, manual workers vs. professionals; flexibility: partially flexible, rigid vs. flexible; variability: partially fixed, fixed vs. variable. The dependent variables were the nineteen possible health disorders listed in the question concerning health status: hearing problems, vision problems, skin problems, backache, headache, stomach ache, muscular pains in shoulders and neck, muscular pains in upper limbs, muscular pains in lower limbs, respiratory difficulties, heart disease, injury, stress, overall fatigue, sleeping problems, allergies, anxiety, irritability, and trauma. All of the variables were dichotomized in relation to the presence or absence of the medical disorder or condition. Four questions were also posed that related to psycho-social conditions: 1. In general, do your working hours fit in with your family or social commitments outside work very well, fairly well, not very well, or not at all well? 2. Do you think you will be able to do the same job you are doing now when you are 60 years old?

6 3. Do you think your health or safety is at risk because of your work, or not? 4. On the whole, are you very satisfied, fairly satisfied, not very satisfied, or not at all satisfied with working conditions in your main paid job? Multiple logistic regression analysis was carried out using the STATA 9.0 package (StataCorp, 2001), and both crude and mutually adjusted odds ratios and 95% confidence intervals were estimated. RESULTS Influence of Working Hours on Health and Well-Being 1129 Only 1,423 (6.7%) out of 21,363 workers stated having both flexible and variable working hours. On the other hand, 2,373 (11.1%) workers had both rigid and fixed working hours. The others declared having different combinations of the two conditions: fixed and partially flexible working hours being the most frequently reported (25.7%), followed by partially variable and partially flexible (18.2%). The two variables appeared to be almost completely independent of one other (Kohen s kappa ¼ ). Both flexibility and variability appeared to have a significant influence on almost all the outcomes of the 23 conditions related to health and well-being (see Table 1). In particular, a lack of flexibility ( rigidity ) of working hours proved to be highly associated with job dissatisfaction (OR ¼ 3.13) and the feelingofnotbeingabletodothesamejobattheageof60(or¼ 2.40). It was also associated with lower health and safety in terms of hearing problems (OR ¼ 1.97), trauma (OR ¼ 1.76), injury (OR ¼ 1.75), irritability (OR ¼ 1.79), sleep problems (OR ¼ 1.66), stomachache (OR ¼ 1.67), backache (OR ¼ 1.65), and headache (OR ¼ 1.64), as well as with unfavorable adjustment to family and social commitments (OR ¼ 1.53). On the other hand, less variable ( fixed ) working hours proved to be favorably associated with family and social commitments (OR ¼.29), heart disease (OR ¼.39), sleep problems (OR ¼.43), stomachache (OR ¼.48), anxiety (OR ¼.54), irritability (OR ¼.56), and stress (OR ¼.56). Taking into consideration the interactions between flexibility and variability and the other twelve intervening (or possibly confounding) variables, multiple logistic regression analysis showed physical work, age, and flexibility to be the three most important factors affecting health and well-being (see Table 2). Flexibility was found to be the first most important factor to influence work satisfaction; the second to affect family and social commitments, trauma, overall fatigue, irritability, headaches, and ability to do the same job at the age of 60; the third to influence heart disease, stomachache, anxiety, injury, and the feeling of health being at risk because of work. was found to be the first most important factor for musculo-skeletal troubles, injury, trauma, respiratory and skin problems, overall fatigue, headaches, and the feeling of not being able to do the

7 TABLE 1 Results of the Multiple Logistic Regression Analysis on the Effect of Flexibility and Variability of Working Hours on Health and Psychosocial Outcomes. Crude Odds Ratios and 95% Confidence Interval Outcome Condition Flexibility Variability Hearing problems a 1.80 ( ) NS b 1.97 ( ) NS Vision problem a NS NS b 0.80 ( ) NS Skin problems a 1.39 ( ) NS b 1.54 ( ) 0.79 ( ) Backache a 1.38 ( ) NS b 1.65 ( ) 0.74 ( ) Headaches a 1.28 ( ) NS b 1.64 ( ) 0.78 ( ) Stomach ache a 1.25 ( ) NS b 1.67 ( ) 0.48 ( ) Muscular pains in shoulders and a 1.24 ( ) NS neck b 1.43 ( ) 0.75 ( ) Muscular pains in upper limbs a 1.28 ( ) 0.84 ( ) b 1.53 ( ) 0.78 ( ) Muscular pains in lower limbs a 1.24 ( ) 0.86 ( ) b 1.66 ( ) 0.81 ( ) Respiratory difficulties a 1.34 ( ) NS b 1.51 ( ) NS Heart disease a NS 0.59 ( b NS 0.39 ( ) Injury a 1.55 ( ) NS b 1.75 ( ) 0.75 ( ) Stress a 1.10 ( ) NS b 1.30 ( ) 0.56 ( ) Overall fatigue a 1.10 ( ) 0.87 ( ) b 1.61 ( ) 0.73 ( ) Sleeping problems a 1.37 ( ) 0.82 ( ) b 1.66 ( ) 0.43 ( ) Allergies a 1.42 ( ) NS b 1.60 ( ) 0.78 ( ) Anxiety a NS 0.84 ( ) b 1.34 ( ) 0.54 ( ) Irritability a 1.24 ( ) NS b 1.77 ( ) 0.56 ( ) Trauma a NS 0.73 ( ) b 1.76 ( ) 0.44 ( ) Working hours fit in well with family or social commitments (0 ¼ well, 1 ¼ not well) Health or safety is at risk because of work (0 ¼ yes, 1 ¼ no) Able to do the same job when 60 years old (0 ¼ yes, 1 ¼ no) Satisfied with working conditions in the main paid job (0 ¼ yes, 1 ¼ no) a NS 0.58 ( ) b 1.53 ( ) 0.29 ( ) a 0.80 ( ) 1.22 ( ) b 0.62 ( ) 1.40 ( ) a 1.59 ( ) 0.89 ( ) b 2.40 ( ) 0.88 ( ) a 1.69 ( ) NS b 3.13 ( ) 0.89 ( ) Note. Condition a refers to partially flexible or partially variable vs. flexible or variable, respectively; condition b refers to fixed or rigid vs. flexible or variable, respectively. 1130

8 TABLE 2 The Three Most Significant Factors Associated with the 23 Health Outcomes According to the Logistic Regression Analysis. Mutually Adjusted Odds Ratios are Reported into Brackets (all at p,.01) Outcome First factor Second factor Third factor Hearing problems Vision problems Skin problems Backache Headaches Stomach ache Muscular pains in shoulders and neck Muscular pains in upper limbs Muscular pains in lower limbs Respiratory difficulties Heart disease Injury Stress Overall fatigue Sleeping problems Allergies Anxiety Irritability Trauma Working hours fit in well with family or social commitments Health or safety at risk because of work (2.41) Age yrs (1.70) (2.52) (4.02) (2.18) Age yrs (2.14), age over 54 yrs (1.93) (3.42) (4.68) (3.96) (2.68) Age.54 yrs (9.94), age yrs (7.39), age yrs (3.44) (3.45) Age yrs (2.12) (2.45) Age yrs (3.12), age over 54 yrs (3.10) (2.18) Age yrs (2.49), age yrs (2.16), age.54 yrs (2.09) Age yrs (1.87) (3.03) Night work (2.47) Social environment (3.07) (1.82) (1.59) (1.97) (1.70) (1.55) Shift work (1.86) Age yrs (1.70), age over 54 yrs (1.68) Age over 54 yrs (2.00) (1.94) (2.24) (2.06) (1.93) Time pressure (1.84) (1.87) Night work (2.51) (1.86) (1.78) (1.85) (2.23) (2.41) Night work (1.72) Age over 54 (1.79) Mental load (1.51) Shiftwork (1.56) Age (1.48) Time pressure (1.48) (1.80) Time pressure (1.58) (1.76) (1.70) Age over 54 yrs (1.65) (1.84), Night work (1.81) (1.47) Heavy physical work (1.67) Clerks (.52) Heavy physical work (1.63) Time pressure (1.48) (1.63) Heavy physical work (1.84) Age yrs (2.10) Lack of variability (.43) (1.62) (continued) 1131

9 1132 TABLE 2 Continued Outcome First factor Second factor Third factor Will be able to do the same job when 60 years old Satisfied with working conditions in the main paid job (2.00) (2.83) G. Costa et al. (1.72) (1.88) Note. Odds ratio above 1 means a negative effect, below 1 means a positive effect. Age yrs (.50) (1.33) same job when 60 years old; the second for heart disease, job dissatisfaction, and anxiety; and the third for irritability, stress, and sleep problems. Aging was found to be the first most important factor for heart disease, sleep problems, anxiety, stomachache, stress, irritability, and vision problems; the second for musculo-skeletal troubles; the third for trauma, hearing, and respiratory difficulties. As for the other factors, it is worth noting that:. variability was the third most important factor to influence family and social commitments.. night work was the first most important factor concerning working hours not fitting in well with family and social commitments, the second for sleep problems and health and safety at risk because of work, and the fourth for heart disease.. shift work was the second most important factor for stomachache.. time pressure was the second most important factor for stress and the third for pains in shoulders and neck and headaches.. job: manual work was the first most important factor for hearing problems; the second for musculo-skeletal troubles, injury, allergies, skin and respiratory difficulties; and the third for job dissatisfaction. On the other hand, clerks complained less about overall fatigue.. social environment, in terms of a lack of participation in work organization, was the most important factor influencing the feeling that health and safety are at risk because of work. The interaction among these factors appears quite complex, as evidenced by the two following conditions. Regarding social interference (i.e., working hours not fitting in well with family and social commitments; see Figure 1), night work (OR ¼ 2.47) and lack of flexibility of working hours (OR ¼ 2.41) were the most significant risk factors, followed by shift work (OR ¼ 1.69), lack of participation

10 Influence of Working Hours on Health and Well-Being 1133 FIGURE 1 Mutually adjusted odds ratios (and 95% CI) for working hours fit in not well with family and social commitments. (OR ¼ 1.50), and time pressure (OR ¼ 1.43). Interestingly, being employed (OR ¼.33) and having more fixed working hours (OR ¼.43) appeared to be positive factors, as well as being a manual worker (OR ¼.83) with low physical work (OR ¼.80), and being a woman (OR ¼.78). Regarding sleep problems (Figure 2), besides the well-known association with aging (OR ¼ 3.12 for those over 40), night work (OR ¼ 2.51) was the most important risk factor, followed by shift work (OR ¼ 1.61), lack of flexibility of working hours (OR ¼ 1.53), and time pressure (OR ¼ 1.51). Also, in this case manual workers appeared to be at a lower risk than clerks and professionals (OR ¼ 0.63), as did having less variable working hours (OR ¼ 0.57).

11 1134 G. Costa et al. FIGURE 2 Mutually adjusted odds ratios (and 95% CI) for sleeping problems. It is also worth noting that the feeling of not being able to do the same job when at 60 years old was mainly associated with poor participation in work organization (OR ¼ 2.01, 95% C.I. ¼ ) and a lack of flexibility of working hours (OR ¼ 1.72, 95% C.I. ¼ ), as well as, though to a lesser extent, night work (OR ¼ 1.34, 95% C.I. ¼ ) and manual work (OR ¼ 1.28, 95% C.I. ¼ ). DISCUSSION Flexible working hours may take on several meanings and be arranged in a number of ways to suit the worker and employer (e.g., from part-time to overtime, from split shifts to night work, from on-call to on-project

12 Influence of Working Hours on Health and Well-Being 1135 work). This article attempted to verify whether, in the condition of full-time work, some arrangement of working hours aimed at reducing their fixity and rigidity were able to improve worker s health and wellbeing. Thus, two aspects of flexible arrangement of working hours were considered: the first was more subjected to company control and decision and related to less fixed working timetables (variability), and the second was more connected to individual discretion and autonomy and related to a less rigid planning of working time ( flexibility). Flexibility and variability of working hours appeared inversely related to health and psycho-social well-being. The most favorable effects were associated with higher flexibility and lower variability. This seems to be easily understood, not only because of the totally different control the workers exert on them, but also because they deal with different domains in terms of biological and psycho-social adaptation. In fact, having more fixed working hours makes possible a more stable regimen of basic physiological functions (e.g., sleep and meals) and a better planning of everyday life in terms of social integration with family members and leisure activities. On the other hand, the possibility of reducing some constraints of working hours enables the worker to match working time with personal needs or preferences, thus limiting the inevitable work/non-work conflict (Loudon and Bohle, 1997). Also, Janssen and Nachreiner (2004) found that a high variability in both duration and position of working hours is associated with impairment in health and wellbeing. This is particularly true if it is company-controlled, while it is less pronounced if it is self-controlled. While the company s demand for higher variability is prevalently related to the short-term adaptation to economic and productive pressures, the individual s demand for higher flexibility is more related to mid- and long-term planning and the harmonization of working and non-working life. A proper balance between these two components can counteract some of the deregulatory trends in working time and prove that the flexibility of arrangements of working hours are not merely a tool to compensate for inadequate planning, poor organization, or chaotic market structures (International Labour Office, 1995). Obviously, the strong positive influence of more flexible working hours on almost all health and psycho-social outcomes considered may not be exclusively direct; they may be mediated and/or modulated by other favorable working conditions that can be more easily associated with flexible working hours. In other words, more flexible working hours is one factor pointing to a better work organization, in comparison with more traditional ones, which are normally adopted not as an isolated measure, but in association with other ergonomic interventions (e.g., on workload, human relations, job tasks). Therefore, such better health and psycho-social conditions can be the effect of generally improved working conditions,

13 1136 G. Costa et al. among which flexible working hours play an important role. This was revealed by a multifactorial analysis, which clearly showed that both organizational (e.g., workload, working hours, and job) and individual (e.g., age and gender) factors act concurrently in affecting health and well-being. The results of multiple regression analysis appeared quite consistent and reliable, considering the rationale behind the relations between intervening factors and health outcomes. For example, heavy physical workload is the most crucial factor for musculo-skeletal disorders, overall fatigue, trauma, and injuries, and age has a considerable effect on heart diseases, sleep problems, vision troubles, anxiety, and irritability, as well as musculo-skeletal problems. Other important aspects related to the working hours organization, such as shift and night work, were confirmed to have a significant influence on sleep, digestive, and cardiovascular disorders, as well as on health and safety at work, as widely reported in the literature (Åkerstedt, 2003; Folkard and Tucker, 2003; Knutsson, 2003). Time pressure also showed a relevant influence both on individual stress and social life. It is worth stressing that a low grade of participation in work organization is the most important factor that influences the feeling that health and safety are at risk because of work, thus emphasizing the importance of the workers involvement in decisions about their working conditions, including their working hours (Kogi and Di Martino, 1995). Suitable arrangements of flexible working time, aimed at supporting workers coping strategies, appear to have a clear beneficial effect on their health and well-being, with positive consequences also at company and social level, as evidenced by the higher feeling to being able to work until 60 years of age. In a large Swedish survey, Åkerstedt et al. (2003) foundthathavingvariedlengthofworkshifts,lowinfluenceoverwork hours, and unwanted overtime increased the risk of quitting work before the normal age of retirement. This is a crucial point especially now taking into consideration the effects of the globalization, both in developing and developed countries (International Labour Office, 2004), the progressive aging of the population, consequent delayed retirement age (Härmä and Ilmarinen, 1999), and the massive entry of women into the labor market. More individually tailored and flexible arrangements of working hours are certainly one of the necessary tools for dealing properly with diversity and equity (Nachreiner, 2004), as well as for achieving the right balance between profitability and humanity (Knauth, 2000). ACKNOWLEDGMENT The study was funded by the SALTSA project Flexible working hours, health and well-being, contract no. Dnr / , V-kod

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