Which of the following antidepressants is least likely to cause sedation?

Paroxetine is a selective serotonin reuptake inhibitor (SSRI), which is known for its antidepressant properties with a relatively favorable side effect profile regarding sedation. SSRIs tend to be less sedating compared to other classes of antidepressants, particularly when compared to tricyclic antidepressants (TCAs) or other medications that have antihistaminic effects.

Trazodone, although effective for depression, is often used off-label for sleep due to its sedative properties, as it acts on serotonin receptors and also has antihistaminic effects. Doxepin, another TCA, has significant sedating properties because of its strong antihistaminic activity, making it effective for insomnia but likely to cause sedation. Clomipramine, also a TCA, has similar sedative characteristics due to its side effect profile.

In summary, paroxetine's mechanism of action and side effect profile align with its lower likelihood of causing sedation, making it the correct choice in this context.