Objectives Sleep disturbances are common in chronic fatigue syndrome (CFS), and one of the key symptom complaints, yet it has been neglected by previous qualitative research. The aim was to explore the specific role of sleep in patients' experience of their illness. Design A qualitative semi-structured interview format facilitated a detailed and open exploration of sleep, and the extent to which its management and problems were linked to the lived experience of CFS. Methods Eleven semi-structured interviews were conducted with individuals with CFS. Data were transcribed verbatim and analysed thematically, to explore and describe patients' experience of their sleep, and its impact on their condition. Results Sleep emerged as a key aspect of the illness experience, and its management and effect on daytime functioning was a central pre-occupation for all 11 participants; all of them saw sleep as playing a critical role in their illness through either maintaining or exacerbating existing symptoms. Exploration of individual experiences presented three overarching themes: (1) sleep pattern variability over illness course and from day to day; (2) effect of sleep on daytime functioning; and (3) attempts at coping and sleep management. Conclusions Each patient with CFS has a unique experience of sleep. Despite the differing narratives regarding the role of sleep in CFS, all participants held the belief that sleep is a vital process for health and well-being which has had a direct bearing on the course and progression of their CFS. Also, every participant regarded their sleep as in some way ‘broken' and in need of management/repair. Patients' insights demonstrate sleep-specific influences on their CFS, and the impact of disturbed sleep should be a consideration for clinical and research work.