“…Apart from 18 F-FDG and 99m Tc-ECD tracers, a variety of additional radioligands that specifically target neurotransmitters that are highly implicated in sleep, or sleep control and cognition (e.g. acetylcholine, serotonin, and dopamine) are increasingly available on the market, for in detail review see Dang-Vu et al (2014).…”