Absence of a diurnal rhythm of oxytocin and arginine-vasopressin in human cerebrospinal fluid, blood and saliva.

•Diurnal variations of central neuropeptide concentrations have been described in several species including humans•We could not show circadian rhythmicity of central OXT and AVP levels in neurocritical care patients under basal conditions•No strong correlations between central and peripheral neuropeptide concentrations could be detected•Correlations of oxytocin CSF and saliva levels may depend on the timepoint of sampling