在許多哺乳動物體內，松果體所分泌的褪黑激素荷爾蒙對於其睡眠與覺醒之晝夜節律扮演一個很重要的角色。患有急性精神錯亂症狀或譫妄的病人，特別是有潛在性認知障礙的患者，經常受苦於睡眠障礙和晝夜節律紊亂。為能提供近來對譫妄的病因及潛在病理生理機轉的認知，本文描述譫妄之致病機轉及譫妄症狀與失智症症狀比較之概述，並呈現褪黑激素相關之晝夜節律紊亂所引發的譫妄。最後，本文論述現行譫妄的治療方法，並檢視褪黑激素於譫妄及失智症之治療及預防效果，包括近年來的研究成果及臨床試驗報告。

The pineal hormone melatonin plays a major role in circadian sleep-wake rhythm in many mammals, including humans. Patients with delirium, especially those with underlying cognitive impairment, frequently suffer from sleep disturbances and disturbed circadian rhythm. In order to provide an update on the understanding of the etiology and potential pathophysiological mechanisms of delirium, we overview delirium and delirium symptoms that correspond with symptoms in dementia followed by a presentation of the circadian rhythm disorders in delirium in relation to melatonin deficiency. Finally, this review examines the therapeutic benefit of melatonin treatment in disorders related to delirium and dementia including the recent randomised clinical trials addressing this topic.