Sleep disturbance has been highlighted as one of the key difficulties for people diagnosed with Fibromyalgia Syndrome (FMS). Objective findings have revealed that there may be underlying changes in the sleep structure for this population. However, there is little evidence regarding how people perceive their sleep quality, the nature of the specific difficulties they experience or how sleep affects their daily lives. The purpose of this thesis was to explore the nature and extent of sleep difficulties in people with FMS, the psychological factors that may contribute to poor sleep quality and the impact of sleep on people’s lives. The thesis also aimed to explore a possible strategy for the management of sleep disturbance in FMS. After completion of a literature review of research focusing on sleep and FMS, mixed research methods were applied to address the aims of this thesis. Two quantitative studies, (one utilising a cross-sectional questionnaire and the other using a case-control design), explored the sleep quality in people with FMS and the links between sleep and other symptoms of FMS. A qualitative study using interpretative phenomenological analysis was employed to elaborate on these quantitative findings, to explore what sleep disturbance means to people with FMS. A pilot study was then conducted to explore a possible intervention to improve sleep quality for people with FMS based on the findings of the previous three studies. Sleep disturbance was found to affect a greater number of people with FMS than previously identified. Poor sleep quality had a profound effect on people’s lives, affecting other symptoms of the condition such as pain and fatigue, as well as reducing their ability to engage in daily activities. Night-time awakenings and feelings of high levels of arousal on awakening were found to have the most profound impact in FMS, with people experiencing ‘blocks of sleep’ lasting several hours throughout the night. Psychological factors such as negative affect, perceived levels of stress and beliefs about sleep were found to be significantly associated with poor sleep quality. A brief mindfulness based intervention aiming to reduce stress and cognitive arousal, proved to be feasible and showed positive trends in sleep quality post-intervention in comparison to a PMR control group intervention, and may be a potential treatment intervention for people with FMS. The role of sleep in FMS appears to be more complicated than previously described, with sleep, psychological factors and health outcomes highly interlinked. A revised model displaying the relationships between sleep and pain is proposed based on the findings of this thesis. Non-pharmacological interventions specifically aimed at improving perceived sleep quality should form an important component to treatment approaches for people with FMS.