['Between 25% and 40% of prostate cancer patients report insomnia symptoms. Although a possible role of androgen deprivation therapy (ADT) and radiation therapy (RTH) and some of their side effects have been postulated, this issue has rarely been investigated. This study aimed to (1) compare the evolution of insomnia symptoms and somatic symptoms, which may affect sleep quality (i.e., hot flashes, night sweats, and urinary symptoms), in patients receiving combined ADT and RTH with that in patients receiving RTH only and (2) assess the mediating role of somatic symptoms in the relationship of ADT and RTH with insomnia symptoms.', 'Sixty men scheduled to receive RTH for prostate cancer, with (n = 28) or without (n = 32) ADT, were assessed prior to receiving any treatment (baseline) and at seven additional times over 16 months (1, 2, 4, 6, 8, 12, and 16 months) using the Insomnia Severity Index and the Physical Symptoms Questionnaire.', 'A significant interaction effect was found indicating an increase in insomnia scores in ADT-RTH patients at 2, 4, and 6 months, as compared with baseline, and stable scores in RTH patients. A significant mediating role of hot flashes and night sweats was found in the relationship between ADT and insomnia symptoms. The relationship with RTH was also significantly mediated by these two symptoms albeit more strongly by excessive urinary frequency.'] Are prostate cancer treatments and their side effects associated with increased insomnia?