Background: This research explores and represents the sleep of people caring for a family member with cognitive impairment or dementia. Methods: A thematic analysis was applied to the open-ended comments from 526 carers from a postal survey concerning sleep, health and caregiving. Themes are presented within a framework of five dimensions of sleep health. Findings: Themes of sleep duration included striking a balance between 'achieving the hours' whilst also sacrificing sleep to manage responsibilities. Themes of sleep efficiency included symptoms of insomnia ('losing sleep over the situation') and 'sleeping on guard' in case night-time support was required. Timing of sleep was themed as either restricted to 'when the one I care for sleeps' or salvaged as a luxury 'quiet time'. Levels of alertness were represented within themes of being 'tired all of the time' whilst also in a state of 'high alert'. Finally, overall sleep satisfaction ranged from themes concerning 'sleeping fine at the moment' to sleep being 'a big problem'. Conclusion: The sleep experience of family carers is unique and often includes tensions between roles and responsibilities and their own need for sleep and well-being. Findings have implications for community support and healthcare interventions for families affected by dementia.