However, testosterone suppression does not appear to be the sole driver for the fatigue and insomnia observed in prostate cancer patients, as other local treatments such as radiotherapy (external beam or brachytherapy) and surgery are also contributory, suggesting that an unbalance in the level of inflammatory cytokines such as interleukins and tumour necrosis factor-alpha (TNF-alpha) are involved in dysregulated sleep patterns [119,120]. Here, TNF is linked to insomnia.