What central nervous system effects are commonly associated with nicotine?

Nicotine primarily exerts its effects on the central nervous system by acting as a stimulant, leading to a variety of symptoms associated with its use. Dependence forms when the body becomes accustomed to nicotine, resulting in cravings when the substance is not available. Stimulation occurs as nicotine enhances vigilance and arousal, often leading to increased focus. These effects are what contribute to both the reinforcing qualities of nicotine and the challenges associated with smoking cessation.

The other options present effects that are more characteristic of substances that induce sedation or relaxation, which is not aligned with nicotine's stimulating properties. Memory loss and confusion, as well as increased fatigue and sleepiness, do not accurately describe the effects that nicotine typically produces in users, as it is more associated with enhanced mental alertness rather than cognitive decline or fatigue.