Does effective management of sleep disorders reduce cancer-related fatigue?

Cancer and cancer therapy are often associated with symptoms such as fatigue and sleep disturbances, before, during and after therapy. These symptoms of fatigue and poor sleep often occur in parallel having a significant impact on the physical functioning of patients with cancer. A strong correlation between cancer-related fatigue (CRF) and sleep has been observed in several studies, suggesting that they may be reciprocally related. The co-clustering of these symptoms suggests that they may have similar underlying aetiology and that treatments targeting either symptom may positively affect the other. Studies examining these clusters have shown that these symptoms often co-vary together. The potential mechanisms that link the relationship between insomnia and CRF are intriguing but require further investigation. Despite the high prevalence of insomnia and the often bidirectional relationship between poor sleep and fatigue, there are limited data to support the use of sleep management interventions as a means to reduce fatigue in patients with cancer. Assessment of the available evidence across trials is complicated by different study designs, patient selection criteria, stage of cancer treatment and by the nature of the interventions studied. Improvements from baseline in both sleep parameters and CRF have been documented in a limited number of studies, including two randomized-controlled trials using cognitive behavioural therapy for insomnia (CBT-I). In contrast, the efficacy of pharmacological therapies in reducing both insomnia and CRF is largely lacking. Clearly, treating clinically significant insomnia is likely to have benefits for the patient with cancer and for those who are recovering from cancer. In particular, pharmacotherapies for insomnia, singly or in combination with CBT-I, should be evaluated in multicentre randomized clinical trials to examine their efficacy in improving sleep quality and reducing associated CRF.