OBJECTIVES: From SISYPHE - a case-control study in occupational health institution in Paris area- we calculated indirect costs associated to insomnia. METHODS: Number and duration of work absence, reported retrospectively over the last 2-year period by a group of insomniac employees and a group of good sleeper employees, were basic data for the calculation of indirect costs. We adopted the perspective of the Sickness Fund (SF) for the private sector and the perspective of the employer (productivity) for the private and the public sector. The costing was performed combining number and duration of work absence, the level of incomes of employees in 2000, the annual number of workdays, the SF rules and employer rules for the coverage of workdays loss in private sector and the published added value for the evaluation of loss of productivity. RESULTS: A total of 568 work absence were reported from 313 employees (public+private sector). Average duration of work absence per employees were 12.9 days (±2.27) and 10.2 (±2.02) days for insomniac and good sleeper respectively. Incremental cost associated to insomnia in the perspective of the SF for employees of private sector was estimated at 130€ per year for insomniac employee. The rate of coverage by the SF represents 26 % of the total coverage (SF+employers). Incremental loss of productivity associated to insomnia is estimated at 1419 € per year for insomniac employee. CONCLUSIONS: Design of SISYPHE allows us to calculate indirect cost associated to insomnia. We observe SF accounts only for one quarter of the total coverage. Loss of productivity is 10-fold higher compared to SF coverage.