This article proposes and tests a model that highlights how organisational embeddedness relates to insomnia. It argues that support rendered by the organisation in general and by supervisors in particular decrease the likelihood that highly embedded employees will experience insomnia. Data collected from 192 managers at four points in time over a 12-month period generally support the proposed model. The article concludes with implications for future research on the relationship between embeddedness and insomnia and the important roles which workplace support systems play in mediating that relationship.