Mechanistically, Oleamide does not appear to have much affinity for GABAA receptors[7] although it has been demonstrated to potentiate signalling via the GABAA receptor in vitro,[32][37] which also appears to apply to oleic acid itself[37] (contested[32]). Oleamide does not alter binding of GABA to the GABAA benzodiazepine receptor at concentrations up to 50mM.[2][5][30]
May not have significant interactions with GABA or Benzodiazepine receptors directly, but may potentiate signalling of the receptors via other agents. Oleamide is likely a GABA synergist
Oleamide is known to, after intravenous injection, induce a dose-dependent induction of sleep with concomitant decreases in wakefulness and sleep latency (time required to fall asleep)[2][29] and dose-dependent decreases in body temperature.[38] Injections of 25, 50, and 100mg/kg Oleamide reduce sleep latency by 13, 24, and 33% repectively while 200mg/kg had a 28% reduction (dose dependence not present at this dose).[29]
In an open-field test of locomotoin, the ED50 (dose causing half of the observed effect) of reducing locomotion appeared to be an injection of 17+/-1.5mg/kg[2] with another study noting an ED50 of 10-19mg/kg.[22] Other studies have noted dose-dependent decreases in locomotor activity at injection doses as low as 2.5mg/kg,[38] and following injections the reduction in locomotion appears to last up to 60 minutes (most efficacy at 30 minutes) and is normalized 2 hours after injection.[22]
This locomotion induced by Oleamide is further reduced 70% with pretreatment of a 5HT1A antagonist while being partly reversed (77%) by a D2 antagonist.[22]
Oleamide injections appear to cause dose-dependent reductions in the time required to fall asleep and reductions in locomotion in research animals with high reliability
In regards to REM sleep, injections of 25-200mg/kg Oleamide in rats failed to significantly influence REM sleep[29] and lower doses (2.5-20mg/kg) also fail to increase REM despite reducing sleep latency.[38] One study has noted an increase in REM sleep with single and 15 days injections of oleamide (25mcg) intracerebrally,[39] but is the least practical research method used (when assessing how oral supplementation would work).
Although it has at times been implicated in improving REM sleep, this does not seem to be reliably seen