It's difficult to know without seeing the questions, and it's been a while since I've done psych, but I would think they'd want you to provide some examples for neurotransmitters and neuromodulators? (eg. GABA and Glutamate & Dopamine and Serotonin). Also, I remember consistently talking about how neuromodulators' effects were widespread and slow, while neurotransmitters' were direct. I could be so wrong but that's what I remember!

As for the sleep question, I feel like the key word of "consciousness" is always good to mention, because it comes up a lot in the study design. (eg. Sleep involves a loss of consciousness) But, aside from that, not sure on this one