Study objectives: To examine cross-sectionally and prospectively whether informal caregiving is related to sleep disturbance among caregivers in paid work.; Methods: Participants (N=21 604) in paid work from the Swedish Longitudinal Occupational Survey of Health. Sleeping problems were measured with a validated scale of sleep disturbance (Karolinska Sleep Questionnaire). Random-effects modelling was used to examine the cross-sectional association between informal caregiving (self-reports: none, up to 5h per week, over 5h per week) and sleep disturbance. Potential socio-demographic and health confounders were controlled for and interactions between caregiving and gender included. Longitudinal random-effects modelling of the effects of changes in reported informal caregiving upon sleep disturbance and change in sleep disturbance were performed.; Results: In multivariate analyses controlling for socio-demographics, health factors and work hours, informal caregiving was associated cross-sectionally with sleep disturbance in a dose-response relationship (compared to no caregiving, up to 5h of caregiving: β = .03; 95% CI: .01; .06, over 5h: β = .08; 95% CI: .02; .13), results which varied by gender. Cessation of caregiving was associated with reductions in sleep disturbance (β = -.08; 95% CI: -.13; -.04).; Conclusions: This study provides evidence for a causal association of provision of informal care upon subjective sleep disturbance. Even low intensity care provision was related to sleep disturbance among this sample of carers in paid work. The results highlight the importance of addressing sleep disturbance in caregivers.