While increases in GM-CSF were found in patients with chronic fatigue syndrome (Montoya et al., 2017), depression (Schmidt et al., 2014), and chronic insomnia disorder (Xia et al., 2021), we hypothesize that increased GM-CSF may be related to a more pronounced pro-inflammatory response associated with a higher symptom burden. Here, CSF2 is linked to myalgic encephalomeyelitis/chronic fatigue syndrome.