Melatonin deficiency hypothesis in delirium: a synthesis of current evidence.

The pineal hormone melatonin plays a major role in circadian sleep-wake rhythm in many mammals, including humans. Patients with acute confusional state or delirium, especially those with underlying cognitive impairment, frequently suffer from sleep disturbances and disturbed circadian rhythm. In this review, an overview is given of delirium and delirium symptoms that correspond with symptoms in dementia, such as sundowning, 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 placebo-controlled randomized clinical trials addressing this topic.