Effort-reward imbalance, overcommitment, and measures of cortisol and blood pressure over the working day.

OBJECTIVE: To assess the biological correlates of effort-reward imbalance and overcommitment to work using measurements over the working day.
METHODS: Participants were 197 working men and women aged 45 to 59 years, recruited from the Whitehall II epidemiological cohort. Salivary cortisol was sampled on waking, 30 minutes later, and then at 2-hour intervals from 8:00 hours to 22:00 hours. Blood pressure was measured every 20 minutes using ambulatory methods. Effort-reward imbalance and overcommitment to work were assessed with standard questionnaires.
RESULTS: Cortisol responses to waking were positively associated with overcommitment in men, with mean increases between waking and 30 minutes of 14.5 and 4.2 nmol/l in high and low overcommitment groups, after adjustment for age, socioeconomic position, smoking, time of waking up, and job demands. Cortisol averaged from 8 samples over the working day was also related to overcommitment in men, with an average difference of 22% between high and lower overcommitment groups. Overcommitment predicted systolic blood pressure over the day in men after adjustment for age, smoking, body mass index, physical activity, and job control, with adjusted means of 132.2 and 125.8 mm Hg in high and low overcommitment groups. There was a significant interaction between overcommitment, socioeconomic position, and time of day in men (p =.016), because systolic pressure was higher in lower status overcommitted men, and rose over the day. Neither effort-reward imbalance nor overcommitment predicted biological responses in women.
CONCLUSIONS: Chronic neuroendocrine and cardiovascular activation may mediate in part the impact of overcommitment to work on cardiovascular disease risk in men.