Association between work schedules and motivation for lifestyle change in workers with overweight or obesity: a cross-sectional study in Japan

Abstract

Objective: To investigate the association between work schedules and motivation for behavioural change of lifestyle, based on the transtheoretical model (TTM) in workers with overweight or obesity.

Design: A cross-sectional observational study.

Setting: A healthcare examination centre in Japan.

Participants: Between April 2014 and March 2016, we recruited 9243 participants who underwent healthcare examination and met the inclusion criteria, namely, age 20-65 years, body mass index (BMI) ≥25 kg/m2 and full-time workers.

Exposure: Night and shift (night/shift) workers were compared with daytime workers in terms of motivation for behavioural change.

Primary and secondary outcome measures: The primary outcome was action and maintenance stages of change (SOC) for lifestyle in TTM. In a subgroup analysis, we investigated interactions between characteristics, including age, sex, BMI, current smoking, alcohol habits, hours of sleep and working hours.

Results: Overall, 1390 participants (15.0%) were night/shift workers; night/shift workers were younger (median age (IQR): 46 (40-54) vs 43 (37-52) years) and the proportion of men was lesser (75.4 vs 60.9%) compared with daytime workers. The numbers of daytime and night/shift workers in the action and maintenance SOC were 2113 (26.9%) and 309 (22.2%), respectively. Compared with daytime workers, night/shift workers were less likely to demonstrate action and maintenance SOC (adjusted OR (AOR): 0.85, 95% CI: 0.74 to 0.98). In a subgroup analysis that included only those with long working hours (≥10 hours/day), results revealed a strong inverse association between night/shift work and action and maintenance SOC (AOR: 0.65, 95% CI: 0.48 to 0.86). A significant interaction was observed between long working hours and night/shift work (P for interaction=0.04).

Conclusions: In workers with overweight or obesity, a night/shift work schedule was associated with a lower motivation for behavioural change in lifestyle, and the association was strengthened in those with long working hours.

Keywords: behavioural change; obesity; the transtheoretical model (TTM); work schedule.

Conflict of interest statement

Competing interests: None declared.

© Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.

Figures

Figure 1

Flow diagram of the study. TTM, the transtheoretical model.

Figure 2

Adjusted ORs for primary outcome (demonstration of action or maintenance stages) in selected subgroups. *Each OR (for primary outcome: demonstration of action or maintenance stages) was adjusted for age (<40 years vs ≥40 years), sex, comorbidities (diabetes, CAD, CVD, cancer), BMI (25–29.9 kg/m2 vs ≥30 kg/m2), current smoking status (yes vs no), alcohol habits (<3 times/week vs ≥3 times/week), hours of sleep (<7 hours vs ≥7 hours), hours of work (<10 hours vs ≥10 hours). Interactions between work schedules and prespecified subgroups were evaluated in the multivariable logistic regression models. BMI, body mass index; CAD, coronary artery disease; CVD, cerebrovascular disorder; SOC, stages of change.