Insomnia and other sleep disorders are common among patients receiving palliative care, with a frequency of 25–87%. Risk factors for sleep disorders can be divided into 4 groups: physical, psychological, medical care-related, and personal and environmental. Although the pathophysiological mechanism behind sleep disorders among patients receiving palliative care is not clear, some mechanisms have been described. These include the presence of a specific sleep pattern and sleep debt, the coexistence of a neurobiological and cognitive-behavioural component, the influence of pro-inflammatory cytokines, and the influence of a central nervous system tumour on surrounding tissues. Diagnostic methods can be classified into objective methods, such as polysomnography and actigraphy, and subjective methods, such as sleep assessment questionnaires and sleep diaries. Due to the high intensity of the psychological component and the short duration of the study, subjective methods are considered the most appropriate for patients receiving palliative care.