This chapter delivers a detailed examination of central nervous system (CNS) pharmacology, concentrating on three significant drug classes relevant to anaesthesia and perioperative care: anticonvulsants, antidepressants, and hypnotics. The chapter first addresses anticonvulsants, outlining their diverse mechanisms, including sodium channel blockade, GABA enhancement, and modulation of calcium channels and glutamate transmission. It reviews essential anticonvulsant agents such as levetiracetam, lamotrigine, phenytoin, carbamazepine, and sodium valproate, highlighting clinical considerations such as perioperative management and teratogenic risks. The antidepressant section explores major drug classes—SSRIs, SNRIs, TCAs, MAOIs, NDRIs, and TeCAs—focusing on their pharmacodynamics, pharmacokinetics, clinical applications, and notable adverse effects including serotonin syndrome and QT prolongation. Finally, the chapter reviews hypnotics, particularly benzodiazepines and Z-drugs, examining their GABA-A modulatory mechanisms, clinical applications (e.g., status epilepticus, insomnia, alcohol withdrawal), and associated risks such as dependence, withdrawal, and respiratory depression. This comprehensive overview ensures trainees acquire essential knowledge for the safe and effective clinical use of CNS-active drugs in anaesthetic and critical care practice.