Name an atypical antidepressant that is primarily used for its sedative effects.

Mirtazapine is recognized as an atypical antidepressant that is often used for its sedative effects. This medication works by antagonizing certain receptors in the brain, including histamine H1 receptors, which contributes to its sedating properties. Additionally, mirtazapine's effects on serotonin and norepinephrine balance help improve mood, making it effective in treating depression.

Unlike other options listed, such as duloxetine, bupropion, and fluoxetine, which may have activating effects or are more commonly associated with treatment for anxiety or depression without significant sedation, mirtazapine's primary clinical use includes its ability to help patients who struggle with both depression and insomnia. This sedative quality makes it a unique choice among antidepressants, particularly for individuals who also suffer from sleep disturbances related to their depressive symptoms.