Some science behind the scenes
Nuciferine – is a glutamate antagonist, in effect it has an action much like a GABAA agonist [see Nuciferine and central glutamate receptors- Curtis DR, Lodge D, Bornstein JC; PMID: 41920]. Glutamate is an excitory neurotransmitter that at high doses can cause seizure. Glutamate agonists can be neurotoxic as they may over excite glutamate receptors, glutamate antagonists in contrast stop the neurotoxicity and calm everything down. GABAA is a neurotransitter that has a similar effect, but is an endogenous chemical. The effects of nuciferine are said to “ induce catalepsy, inhibit spontaneous motor activity, conditioned avoidance response, amphetamine toxicity and stereotypy”. [Source Bhattacharya SK, Bose R, Ghosh P, Tripathi VJ, Ray AB, Dasgupta B (Sep 1978). Psychopharmacological studies on (—)-nuciferine and its Hofmann degradation product atherosperminine". Psychopharmacology (Berl.) 59 (1): 29–33] So you slow down and seize up a bit – it affects locomotor activity.