ann. behav. med. (2009) 37:184–196 DOI 10.1007/s12160-009-9087-6
ORIGINAL ARTICLE
Exploring the Benefits of Conscientiousness: An Investigation of the Role of Daily Stressors and Health Behaviors Daryl B. O’Connor, Ph.D. & Mark Conner, Ph.D. & Fiona Jones, Ph.D. & Brian McMillan, Ph.D. & Eamonn Ferguson, Ph.D.
Published online: 26 March 2009 # The Society of Behavioral Medicine 2009
Abstract Background and Purpose This study investigated the impact of conscientiousness and its facets on health behaviors and daily hassles (stressors) and the moderating effects of conscientiousness on the hassles–health behavior relationship Methods Four hundred and twenty-two employees completed daily diaries over 4 weeks. Day-to-day within-person effects of daily hassles on health behaviors were examined, together with the influence of conscientiousness. Results Using hierarchical multivariate linear modeling, the results showed that conscientiousness was associated with lower consumption of high-fat snacks and more fruit and higher caffeine intake and smoking (in smokers) across the 28-day study period. Facets of conscientiousness were also found to moderate the effects of daily hassles on vegetable consumption, smoking, and likelihood of exercising each day. Participants with higher levels of order exercised more on days when they experienced daily hassles, whereas participants with lower levels of self-efficacy consumed less vegetables on stressful days. Among smokers, those with higher levels of self-discipline reported smoking more on days when they encountered hassles. Conclusions These findings indicate that conscientiousness and its facets may influence health status directly via changes in health behaviors and indirectly through influencing stress–health behavior relations. D. B. O’Connor (*) : M. Conner : F. Jones : B. McMillan Institute of Psychological Sciences, University of Leeds, Leeds, UK LS2 9JT e-mail:
[email protected] E. Ferguson Department of Psychology, University of Nottingham, Nottingham, UK
Keywords Stress . Health behaviors . Personality . Coping . Daily diaries . Hassles
Introduction There is a growing body of research that has demonstrated that conscientiousness is associated with longevity and health status [1–5]. Friedman et al. [2], using data from the Terman Life Cycle Study, reported that childhood conscientiousness predicted longevity and the magnitude of this effect (as a risk factor) was comparable to those from elevated serum cholesterol and systolic blood pressure levels in adulthood. Much of the work has focused on potential explanatory mechanisms that may transmit these beneficial effects over the life course. For example, Friedman et al. [3] found that the protective influence of childhood conscientiousness on health status was accounted for, in part, by its impact on health behaviors such as alcohol use and smoking. More recently, from a diathesisstress perspective, researchers have also found that conscientiousness has the capacity to moderate stress-related changes in health behaviors such that individuals low in conscientiousness respond more negatively to stressful encounters compared to highly conscientious individuals [6–7]. Taken together, these findings suggest multiple pathways through which conscientiousness may exert its protective influence: directly via changes in health behaviors or indirectly through influencing stress–health behavior relations. A third pathway may also exist where conscientiousness directly influences the number of daily hassles (stressors) an individual experiences, thereby, reducing any direct effects of stressors on various bodily systems over time [8]. However, to date, no research has investigated simultaneously the direct effects of conscientiousness on
ann. behav. med. (2009) 37:184–196
health behaviors and daily stressors and its moderating effects on the stress–health behavior link. Consequently, the present study set out to elucidate the relationship between conscientiousness, stress (assessed as daily hassles), and health behaviors in a sample of employed men and women using a multilevel prospective diary design. The study adds to our understanding of the role of conscientiousness in relation to health behaviors not only in terms of direct and moderating effects but also by being the first study to explore these relationships using daily assessments. Therefore, this research addresses the important question of the extent to which conscientiousness is related to the daily initiation of health behaviors. A meta-analysis of the leading behavioral contributors to the conscientiousness–mortality relationship, conducted by Bogg and Roberts [1], showed conscientiousness to be negatively related to health-damaging behaviors (e.g., excessive alcohol use r=−0.25; unhealthy eating r=−0.13; tobacco use r=−0.14) and positively related to healthenhancing behaviors (e.g., physical activity r=0.05). Since the publication of this review, three important additional prospective studies have been reported [4–5, 9]. Two describe how the effects of childhood conscientiousness on health status 40 years later are partially mediated by smoking, body mass index, educational attainment, and healthy eating habits [4–5]. The third showed that both childhood and adult conscientiousness predicted adult mortality, but the effects of adult, not childhood conscientiousness, were mediated by adult smoking and alcohol use [9]. Moreover, other recent work has attempted to explain the impact of conscientiousness on health behaviors in terms of its impact on self-regulation processes. This is because the characteristics and activities associated with conscientiousness (e.g., the ability to control one’s behavior and to complete tasks) are likely to facilitate the performance of aversive or difficult health behaviors that individuals are motivated to perform [10]. Four studies have reported evidence of this relationship [11–14]. For example, Conner et al. [11] reported conscientiousness to moderate the impact of intentions to exercise on exercise behavior but only for exercise completed in nonusual weeks. Similarly, Rhodes et al. [12–13] reported conscientiousness to significantly moderate the intention–exercise behavior relationship, with higher levels of conscientiousness associated with stronger intention–behavior relationships. To date, most of the available evidence has utilized a trait approach and predicted health outcomes from personality traits using cross-sectional or prospective designs (cf., [1]). Of the 194 studies reviewed by Bogg and Roberts [1], only ten investigations were longitudinal with a large majority relying on “snapshot” and/or retrospective measurements of health behaviors. Bogg and Roberts [1] also acknowledge the difficulty in drawing inferences based upon
185
the large number of cross-sectional studies. As a result, it is difficult to discern firm conclusions about the process of how conscientiousness influences future health status. Surprisingly, research in this area has not utilized multilevel daily process studies which: (a) permit frequent measurement of within-person variables (e.g., health behaviors) together with between-person factors (e.g., conscientiousness); (b) reduce recall bias; and (c) allow participants to be used as their own controls (see [9]). Indeed, Bogg and Roberts [1] acknowledged that the overreliance on cross-sectional methodologies represents a substantial weakness and they have suggested that future investigations ought to concentrate on using daily diary approaches to “provide a more definitive test of the relationship between conscientiousness and health-related behaviors” (p. 912). In addition, previous research has ignored the growing body of evidence showing that fluctuations in within-person stressful daily hassles are important in understanding health behavior processes (e.g., [15–19]). For example, O’Connor et al. [19] recently showed that daily hassles have the capacity to disrupt habitual health behaviors such that on days when individuals experienced hassles they consumed significantly more high-fat and sugar snacks. Hassles are events, thoughts, or situations which, when they occur, produce negative feelings such as annoyance, irritation, worry or frustration, and/ or make you aware that your goals and plans will be more difficult to achieve (see [16–17, 20]). Nevertheless, to date, no research has examined whether conscientiousness may exert, in part, its positive influence on health indirectly by moderating the effects of daily hassles, such that conscientious individuals may respond to hassles by engaging in more health-enhancing and less health-damaging behaviors. Alternatively, it is also possible that conscientious individuals may simply experience fewer hassles given they are better organized, prepared, and disciplined. Limited evidence exists that indicates that conscientious individuals are more likely to employ problem-focused coping in response to stress and to perceive themselves as being able to meet situational demands; however, no studies have investigated the relationship between conscientiousness, daily hassles, and health behaviors [6–7]. For example, it is feasible that conscientious individuals may engage in certain types of health behaviors, such as exercise, as a way of actively coping with daily stressors. Therefore, in order to explore these possibilities, we used a multilevel diary design to examine day-to-day within-person effects of daily hassles on a range of health behaviors over 28 days (i.e., high-fat snacks, caffeinated beverages, alcohol, smoking, exercise, fruit and vegetable intake) while simultaneously investigating the influence of conscientiousness as a possible moderating variable.
186
Conscientiousness can be measured in a number of different ways using validated measures such as the NEO Personality Inventory, the International Personality Item Pool (IPIP), the Jackson Personality Inventory, the California Personality Inventory, and so forth [21]. Each measure comprises of different facets of conscientiousness and the lower-order structure of conscientiousness has been the subject of much empirical investigation [21–24]. A large amount of previous research into the conscientiousness–health behavior link has focused on global assessments of conscientiousness but very little on the impact of its lower-order facets on the engagement of health behaviors. Costa et al. [23] have conceptualized conscientiousness as having proactive (e.g., need for achievement) and inhibitive (e.g., cautiousness) aspects which may differentially influence health behaviors. However, no studies have explored the links between these lower-order facets and the daily initiation of health behaviors. Therefore, in the current study, we measured five facets of conscientiousness using items from the IPIP (i.e., selfefficacy, order, achievement striving, self-discipline, and cautiousness), a public domain measure of the Big Five personality factors, in order to advance understanding of which were the most critical facets of conscientiousness. In summary, this study had three main aims: (1) to examine the direct impact of conscientiousness and daily hassles on a range of health behaviors, (2) to investigate whether conscientiousness can moderate daily hassles– health behavior relations, and (3) to test whether individuals high in conscientiousness experience less daily hassles across the study period compared to individuals low in conscientiousness.
ann. behav. med. (2009) 37:184–196
analyses focus on the sample of 422. The mean age of the final sample was 40.26 years (range= 18–65 years). Participants spanned a range of public service occupations, including administrative workers and police and social workers, with a majority (63%) in managerial and professional occupations. Only 7% were in semi-routine or routine occupations. Participants were reimbursed approximately $75 for taking part in the study. Design Participants completed an initial questionnaire, followed by four 7-day daily diaries and a final questionnaire at the end of the study. Diaries were returned at the end of each week and checked against postmarks in order to ensure the participants complied with the study protocol and completed their diary during the appropriate week. As a result, no diaries were excluded. This study received ethical approval from the University Department Ethics Committee. An interval-contingent method was employed, where the participants completed their diary at the end of each day for a period of 4 weeks, with the diary returned by post to the researchers at the end of each week. The use of weekly diaries to collect end-of-day data—especially over an extended period of time—is a well-established protocol in the health, clinical, and social psychology literature (e.g., [25–26]) that has been shown to produce reliable data [27]. End-of-day diaries rather than event-contingent diaries were utilized to increase motivation and compliance with the diary protocol. This procedure reduces participant burden when the time span of the study is long (lasting weeks or months; see [28]) and it has been argued that reduced burden increases participant compliance [27].
Method
Measures
Participants
Participants completed a daily diary form at the end of each day in which they recorded daily hassles and a range of daily health behaviors and they completed a series of questionnaires at the beginning and the end of the study.
Participants were recruited from a large local government organization in the UK. A total of 466 individuals (215 males; 251 females) aged 18–65 years took part in the first round of the study, which consisted of a 1-week daily diary and completion of an initial demographics questionnaire (e.g., age, height, weight). A total of 449 of these individuals (207 males; 242 females) completed the second 1-week daily diary; 443 (202 males; 241 females) completed the third 1-week daily diary; 437 (200 males; 237 females) completed the fourth 1-week daily diary and 428 (197 males; 231 females) completed a final questionnaire. Complete data across all the diaries and final questionnaire were available from 422 participants (193 male, 229 female). There were no differences on the main study variables between the completers and noncompleters. Therefore, all subsequent
Daily Diary Measures Daily Hassles In each 7-day daily diary, participants were requested— using free responses—to report each stressor or hassle experienced and then to rate its intensity on a scale extending from “not stressful” (0) to “very stressful” (4). The results for “actual number” and a combined “total intensity” of hassles by the “actual number” of hassles measure were substantively similar; therefore, only the results for the actual number of hassles are reported. Daily
ann. behav. med. (2009) 37:184–196
hassles were defined as events, thoughts, or situations which, when they occur, produce negative feelings such as annoyance, irritation, worry, or frustration and/or make you aware that your goals and plans will be more difficult or impossible to achieve (see [16–17, 19]). Examples of hassles were provided in each diary booklet. The use of open-ended daily diaries allowed respondents to record day-to-day minor life events or hassles that are part of everyday life and have the advantage of not constraining respondents to a limited number of events, unlike using daily hassles checklists. Thus, in the current study, measuring hassles using a free-response format allowed a large number of stress occurrences in each respondent to be identified, making it possible to look at whether a range of health behaviors coincided with hassles on a number of occasions, enabling a realistic view of daily health behaviors in response to stress. Good interrater reliability and validity have been demonstrated previously for this technique (see [17, 18–20]). Daily Health Behaviors The following health behaviors (fruit consumption, physical exercise, high-fat snack consumption, cigarette use, alcohol and caffeine intake) were assessed each day as outlined below. Between-meal snack consumption was measured by asking participants to list each of the foods they had eaten between meals on each day. For the purpose of this investigation, we were only interested in snacks categorized as being high in fat based upon validated food composition tables [29]. All coding was conducted by a panel of four health psychologists, trained to Ph.D. level with a mean of 13-year research experience, resulting in good interrater reliability with all kappas above 0.70. Portions of fruit consumption were assessed by asking participants to report the number of portions of fruit eaten each day using guidance from the UK Department of Health’s Five-A-Day campaign. Daily cigarette use was assessed by asking participants how many cigarettes they had smoked each day. The response option, “I did not/do not smoke” was also provided. Daily alcohol consumption was assessed by asking participants how many of the following they had consumed on each day: pints of beer/lager/cider, measures of spirits, and glasses of wine. The response option “I did not drink any alcohol today” was also provided. Answers to these questions were combined and converted into units (one unit corresponding to approximately 8 g of ethanol, i.e., a small glass of wine or half a pint of beer). Daily caffeinated beverage consumption was assessed using a single question: “how many drinks containing
187
caffeine have you had today?” with open-response format. Participants were provided with the following information as an aid to identifying caffeinated drinks: “Drinks containing caffeine include tea and coffee, ‘colas,’ e.g., Pepsi or Coke, ‘energy drinks,’ e.g., Lucozade, Red Bull, and many soft drinks, e.g., Irn Bru.” Daily exercise was measured by asking participants if they had participated in any exercise that day (yes=1, no= 0) and if they endorsed the “yes” response they were asked to describe the exercise. This was used to check that responses approximated to descriptions of moderate or vigorous exercise as defined by the International Physical Activity Questionnaire [30]. Questionnaire Measures Conscientiousness was assessed using a 50-item measure from the IPIP [24]—a public domain measure of the Big Five personality dimensions (www.ipip.ori.org/ipip/). Similar to the NEO inventory [23, 31], the IPIP consists of facet scales for each of the five major personality domains. The IPIP facets have been found to correlate highly with its NEO inventory counterparts (rs
