IGF-1 is a hormone stimulated by growth hormone, particularly during deeper “slow-wave” sleep; ME/CFS patients typically experience little sleep at stages III and IV (Fischler et al., 1997) and have lower serum levels of IGF-1 (Berwaerts et al., 1998), with quality of sleep correlated with circulating levels of pro-inflammatory cytokines, and severity and frequency of symptoms, in the disease (Milrad et al., 2017). This evidence concerns the gene IGF1 and myalgic encephalomeyelitis/chronic fatigue syndrome.