Despite most American adults sharing a bed with a romantic partner, sleep research has examined sleep primarily as an individual behaviour. A growing body of research indicates that couple bed sharing may have an impact on sleep quality, but the current study is the first to examine whether such associations may differ based on attachment security. A sample of 179 cohabiting heterosexual couples completed daily sleep diaries and surveys of their attachment security, avoidance and anxiety. Data were analysed using multilevel modelling. Greater attachment security and lower attachment avoidance were associated with greater subjective sleep quality. Greater sleep concordance (time in bed with partners) was associated with better subjective sleep quality for women with lower attachment security and higher attachment avoidance. Findings suggest that couple bed sharing may benefit the subjective sleep quality of women who have lower attachment security.