A prospective study of the impact of variability in insomnia symptoms on work productivity

Previous studies have consistently shown that insomnia symptoms are associated with both presenteeism and absenteeism. However, since these studies were cross-sectional, the longitudinal relationship remains unclear. This study aims to clarify how variability in insomnia symptoms impacts presenteeism and absenteeism.

This prospective study included 4242 daytime workers who attended both baseline and follow-up annual medical check-ups. The follow-up period lasted 11-12 months. Participants were categorized into four groups based on the presence or absence of insomnia symptoms: normal (n = 3032, 71.5%), new-onset at follow-up (n = 329, 7.8%), recovery at follow-up (n = 300, 7.1%), and persistent (n = 581, 13.7%). Presenteeism was assessed by asking about work performance over the past month on a scale from 0% to 100%. Absenteeism was evaluated by inquiring about the number of days absent due to injury or illness over the past month.

The new-onset group had significantly worse presenteeism at follow-up than at baseline (Hedges' g = 0.29). The persistence group had significantly worse presenteeism than the other groups at follow-up (Hedges' g = 0.20-0.53). The new-onset group also had significantly worse presenteeism than the healthy and recovery groups at follow-up (Hedges' g = 0.25-0.33). Both the persistence and recovery groups had significantly increased absenteeism regardless of whether measured at baseline or follow-up (incidence rate ratio = 1.51-1.73).

These findings highlight the importance of optimizing treatment for workers with insomnia in workplace environments.