摘要：Objectives. We assessed whether adequate sleep is linked to more healthful eating behaviors among motor freight workers and whether it mediates the effects of workplace experiences. Methods. Data were derived from a baseline survey and assessment of permanent employees at 8 trucking terminals. Bivariate and multivariate regression models were used to examine relationships between work environment, sleep adequacy, and dietary choices. Results. The sample (n = 542) was 83% White, with a mean age of 49 years and a mean body mass index of 30 kg/m2. Most of the participants were satisfied with their job (87.5%) and reported adequate sleep (51%); 30% reported job strain. In our first model, lack of job strain and greater supervisor support were significantly associated with adequate sleep. In our second model, educational level, age, and adequate sleep were significantly associated with at least 2 of the 3 healthful eating choices assessed ( P < .05). However, work experiences were not significant predictors of healthful food choices when adequate sleep was included. Conclusions. Adequate sleep is associated with more healthful food choices and may mediate the effects of workplace experiences. Thus, workplace health programs should be responsive to workers' sleep patterns. Epidemiological evidence has consistently demonstrated that inadequate sleep duration and compromised sleep quality, independent of other known contributing factors, confer additional risks for weight gain 1 – 4 and obesity 5 – 8 as well as chronic disease. Such findings are of concern given the apparent decrease in the average sleep duration of US adults from 8.5 hours in the 1960s to only 7 hours per night on average by 2000. 9 – 11 Sleep adequacy can be broadly defined as a combination of sufficient sleep duration and sleep quality. Laboratory studies of sleep physiology suggest that, among most adults, adequate sleep duration is approximately 7 to 9 hours. 12 – 14 Large-sample research among adults has shown that those who sleep approximately 7 hours per night are at the lowest risk of mortality. 10 Recent research from both laboratory-based and epidemiological studies indicates that sleep restriction is associated with increased hunger and appetite. 9 , 15 One study in which individuals were randomized to 2 nights of sleep restriction or to adequate sleep showed that, after control for food intake, subjective appetite and hunger were elevated across the entire waking day among those with inadequate sleep, and this elevation was strongly associated with increased ghrelin (a peripheral hunger signal from the stomach to the hypothalamus) and reduced circulating leptin (a peripheral satiety signal from the adipocytes to the hypothalamus), which together drive appetite. 16 A recent controlled clinical study of sleep inadequacy among middle-aged individuals imposed sleep durations of 5.5 hours or 8.5 hours per night, with food freely available to participants. This study demonstrated that the leptin and ghrelin hunger drive was normalized, or the same, in both conditions because the participants with 5.5 hours of sleep time ate on average about 200 kcal (837 kJ) more of food, primarily in the form of snacks, further supporting a role for adequate sleep duration in the control of eating behavior. 17 Complementary cross-sectional epidemiological evidence links short sleep duration with the physiological signal of decreased satiety and increased hunger (reduced leptin and increased ghrelin levels), which is associated in turn with increased body mass index. 7 Additional physiological changes in metabolism among young men resulting from sleep restriction include insulin resistance and hormonal changes 18 – 21 that increase the likelihood of obesity, especially visceral adiposity. Although epidemiological and field studies have linked sleep difficulties with job strain and negative workplace experiences, 15 , 22 workplace effects on dietary preferences are less well understood. Motor freight workers often work long hours, and a variety of factors influence their sleep duration and quality: irregular shifts, mealtimes, and sleep patterns; unsatisfactory sleeping accommodations; and anxiety over traffic, schedules, and economic pressures. 23 – 26 Typically they are on duty for 10 or more hours broken by 8 hours of rest that may or may not provide adequate time and circumstances for sleep. Many drivers work close to the maximum number of hours permitted under the rules of the US Department of Transportation because compensation schedules are tied to work completed. Drivers frequently drive at night to avoid traffic delays and deliver cargo on time. According to one study, a greater percentage of professional drivers (40%) than workers in other job categories (18%) reported experiencing high job strain. 27 The “obligatory vigilance” of extended driving is also a stressful component of the occupation and may cause fatigue. 28 Work practices for professional drivers may influence obesity rates and chronic disease risk, and a larger proportion of male truck drivers than the general adult male population are overweight. 29 A US Department of Transportation survey showed that 90% of truck drivers are at least overweight and 50% are obese, which is approximately double the prevalence of obesity among men in the general adult population. 30 We examined the important role of work experiences in both sleep adequacy and dietary choices among motor freight workers given that, as noted, these individuals are at elevated risk of inadequate sleep and poor dietary patterns. We used the social contextual model of health behavior as a framework to describe the roles that work experiences and job conditions play in shaping workers' health behaviors, including dietary patterns. 31 , 32 Although sleep is a health behavior, obtaining adequate sleep can be affected by socioeconomic factors and workplace experiences, among many other factors. In this study, we tested the hypothesis that adequate sleep is linked to more healthful eating behaviors among motor freight workers and mediates the effects of workplace experiences on diet ( Figure 1 ). We predicted that work experiences, including supervisor support, job satisfaction, and job strain, would be associated with sleep adequacy and that sleep adequacy would be associated with dietary patterns. Open in a separate window FIGURE 1 Conceptual framework of workplace experiences related to dietary choices and sleep adequacy.
