This study examined the effects of two nights of sleep restriction on neuroendocrine hormones (i.e. peptide YY [PYY], ghrelin, glucagon-like peptide-1, adiponectin, and leptin) involved in regulating body weight. Ten healthy male adults aged 18 to 23 years were subjected to two consecutive nights of sleep restriction. Compared to a night of normal sleep, sleep restriction was associated with a significant reduction in PYY levels (P= 0.047) and a significant reduction in satiety levels (P= 0.033). These results suggest that sleep restriction alters the hormonal regulation of appetite in a manner predictive of increased energy intake.