INS and obesity due to melanocortin 4 receptor deficiency: As also mentioned in the introduction, increased ceramide levels have been reported in several conditions frequently accompanying obstructive sleep apnea, such as obesity (Haus et al., 2009), coronary artery disease (Poss et al., 2020), insulin resistance (Boon et al., 2013), diabetes (Fretts et al., 2020), hypertension (Spijkers et al., 2011) or heart failure (Ji et al., 2017).