A 70-year-old non-addict man with the history of diabetes, hypertension and allergic rhinitis was referred for abnormal behavior during the night. The behaviors included shouting, punching, walking during sleep, leaving the house and dream enactment. He also had history of snoring and excessive daytime sleepiness, suspicious of obstructive sleep apnea (OSA). He was suffering from depression for which he was on antidepressants, i.e., mirtazapine, sertraline and olanzapine by a psychiatrist. The abnormal sleep behaviors developed after start of mirtazapine. After ruling out all other causes, he was finally diagnosed to be suffering from drug-induced parasomnia overlap disorder (POD) caused by mirtazapine along with OSA based on international classification of sleep disorders–3rd edition (ICSD-3). He had resolution of the parasomnia episodes after stoppage of mirtazapine.
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