Final answer:
Adrenoceptor agonists generally cause a sympathetic response in the CNS, leading to excitation and insomnia, which corresponds to option b) of the given choices.
Step-by-step explanation:
Two central nervous system (CNS) effects of adrenoceptor agonists are excitation and insomnia. Adrenoceptor agonists, such as adrenaline (epinephrine) and noradrenaline (norepinephrine), bind to α-adrenergic and β-adrenergic receptors, leading to a sympathetic response. In terms of their CNS effects, these substances usually cause an increase in alertness, which can result in insomnia, as well as elevated cognitive functions, leading to excitation. β-blockers, on the other hand, typically have antagonist effects, decreasing heart rate and blood pressure. Considering the information provided, option b) Excitation, insomnia is the correct choice for the question about CNS effects of adrenoceptor agonists.