Oleamide is an endogenous fatty acid amide which can be synthesized de novo in the mammalian nervous system, and has been detected in human plasma.
Oleamide accumulates in the cerebrospinal fluid (CSF) of rats after six hours of sleep deprivation and induces sleep in naive rats and mice. Inhibition of the primary catabolic enzyme of oleamide (fatty acid amide hydrolase) by trifluoromethyl-octadecenone reduces sleep latency and increases total sleep time when given centrally to rats and peripherally to mice[1]
References:
[1]. Mendelson WB, et al. The hypnotic actions of the fatty acid amide, oleamide. Neuropsychopharmacology. 2001 Nov;25(5 Suppl):S36-9.