Achieving healthy sleep supports general health and well-being1,2. Sleep disturbance in type 1 diabetes (T1DM) can be caused by factors including fear of hypoglycaemia and suboptimal glucose control3. For example, hypoglycaemia or hyperglycaemia can disturb sleep, through mechanisms including sympathetic activation and neuropathic pain, respectively4. Several observational studies have suggested that hybrid closed-loop (HCL) system initiation is associated with improved sleep,5,6 but these data could be limited by confounding and other biases. Moreover, different HCL devices could have differing effects on sleep; outcomes could be influenced by user age and the measures by which sleep is assessed. Our objectives, in older adults with T1DM, were to: a) assess the impact of an adaptive HCL system (CamAPS FX) on subjectively and objectively assessed sleep traits in a post hoc analysis of randomised controlled trial (RCT) data; and b) assess the relationship between glucose control and sleep traits in the trial cohort.