Aim: To investigate the relationship between two social support dimensions (network and emotional support) and sleep quality and between two social support sources (at and outside work) and sleep quality. Methods: The three-wave prospective Work Lipids and Fibrinogen (WOLF) study from Northern Sweden was used including 2420 participants who had filled out a questionnaire on working life, life style and health. Sleep quality was assessed by the Karolinska Sleep Questionnaire (KSQ). Structure and function of social support were measured as network support both at and outside work by Availability of Social Integration (AVSI) and emotional support both at and outside work by Availability of Attachment (AVAT). Logistic regression was used, utilizing variables created to assess development over time. Moreover, reversed causation was tested. Results: Improved network support at work decreased the risk of disturbed sleep (OR .65; 95% CI .47 - .90) as did improved emotional support outside work (OR .69; 95% CI .49 - .96). Reporting a constant poor network support at work increased the risk of disturbed sleep (OR 1.53, 95% CI 1.10 - 2.11) as did reporting a constant poor emotional support outside work (OR 1.46; 95% CI 1.02 - 2.05). In men constant good network at work decreased the risk of disturbed sleep (OR .49, 95% CI .34 - .71). Reversed causation analyses indicate some bi-directionality. Conclusion: Being able to perceive social support is a human strength promoting sleep. Both dimension (structure and function) and source (at and outside work) of support matters in sleep quality and seem to be related since the structural dimension was more likely to affect sleep when derived from work, whereas the functional dimension affected sleep quality if it was provided outside work. Men’s sleep seems to be more sensitive to network support at work. Disturbed sleep may also alter the perception of social support.