Our finding of elevated CSF NfL levels among participants who reported greater sleepiness is in agreement with previous literature indicating that EDS is a risk factor for cognitive decline and dementia (Cohen-Zion et al., 2001; Foley et al., 2001; Ohayon and Vecchierini, 2002; Merlino et al., 2010; Elwood et al., 2011; Jaussent et al., 2012; Keage et al., 2012; Tsapanou et al., 2015). This evidence concerns the gene NEFL and Mental deterioration.