The reciprocal relationship between vigor and insomnia: a three-wave prospective study of employed adults.

Vigor is a positive affect experienced at work. It refers to feelings of possessing physical strength, emotional energy, and cognitive liveliness. Accumulated evidence suggests that vigor has a protective effect on health, but the mechanisms of this link remain to be discovered. This study focused on sleep quality as one possible mechanism. We used a full-panel, longitudinal design to investigate the hypothesis that changes in vigor over time have inverse effects on insomnia and vice versa. The study was conducted on a multi-occupational sample of working adults (N = 1,414, 70 % men) at three time points (T1, T2, and T3), over a period of about 3 years. Vigor was assessed by the Shirom-Melamed Vigor Measure, while insomnia was assessed by the Brief Athens Insomnia Scale. Results of SEM-analyses, controlling for neuroticism, and other potential confounding variables, offered a strong support for the study hypotheses, indicating cross-lagged reciprocal inverse relationships between vigor and insomnia. The results suggest that vigor has a protective effect on sleep quality and that vigor might positively influence health through this pathway.