However, while both growth hormone and ghrelin are known to have clear diurnal patterns of secretion, with nocturnal levels being higher than daytime levels in humans, there have been a surprising lack of investigation into the possibility growth hormone abnormalities in PWS may be due to altered diurnal rhythms (Kyung et al., 2004; Stawerska et al., 2020). This evidence concerns the gene GHRL and Prader-Willi syndrome.