Facebook addiction and depression: Loneliness as a moderator and poor sleep quality as a mediator

•Facebook addiction is positively correlated with depression.•Poor sleep quality mediated the link between Facebook addiction and depression.•Loneliness moderated the link between Facebook addiction and depression. Facebook addiction is considered as one of the potential behavior addictions. Data on Facebook addiction among Facebook users in Vietnam is scarce, although this is a research topic that is increasingly attracting the attention of researchers. This study aims to identify the mediating and moderating effects of poor sleep quality and loneliness in the association between Facebook addiction levels and depression among Vietnamese Facebook users. A cross-sectional study was conducted in October 2020 via an online survey. Participants received an invitation to join the study with a link to the questionnaire via Facebook. A total of 354 Facebook users completed survey about Facebook addiction, sleep quality, loneliness and depression. Results reveal that poor sleep quality partially mediated the association between Facebook addiction and depression (b = 0.117, SE = 0.027, CI = [0.066, 0.172]), and loneliness moderated this relationship (β = 0.023, SE = 0.008, CI = [0.007, 0.039]). This research not only enriches the theory of the association between Facebook addiction and depression, but also a basis for the development of intervention programs to prevent depression for Facebook addictors. Accordingly, the intervention should be paid attention to improving the quality of sleep and reducing loneliness for Facebook users.