Assertion: caffeine's effect | /r/HasSubevent | an excess of blood
Facets:
value: in the head
type: LOCATION
Source sentences:
text: Because adenosine, in part, serves to regulate blood pressure by causing vasodilation, the increased effects of adenosine cause the blood vessels of the head to dilate, leading to an excess of blood in the head and causing a headache and nausea.