For example, insomnia is related to alterations in basal inflammatory markers, as indicated by findings of increased levels of interleukin-6 (IL-6) in some studies (Burgos et al., 2006, Vgontzas and Chrousos, 2002), but not in other studies (Floam et al., 2015, see also comprehensive review on sleep disturbances by Irwin et al. 2016). This evidence concerns the gene IL6 and insomnia.