Assertion: brain's neurotransmitter | /r/CapableOf | play key role
Facets:
Source sentences:
text: The exact nature of serotonin's role in sleep has been debated by researchers, but it's believed to influence when, how much, and how well you sleep.﻿﻿ Serotonin does not regulate these tasks alone; other neurotransmitters like dopamine also play a key role.