Delirium is an acute-onset syndrome that exacerbates patients' condition and significantly increases consequential morbidity and mortality. There is no comprehensive, cellular and tissue-level, pathophysiological theory. The melatonin hormone imbalance has been shown to be linked to circadian rhythms, sleep-wake cycle disturbances, and delirium incidence. There has been relatively little research about melatonin in delirium, and there has been no such study done in the group of elderly patients of a general medicine ward yet. The aim of our study was to compare melatonin hormone concentration in relation to the presence of delirium in elderly patients hospitalized in the general medicine ward. Blood samples were collected four times a day for two days (at 12:00, 18:00, 00:00 and 6:00), on the day when delirium was diagnosed and 72 h after the delirium resolution. Delirium was diagnosed with the Confusion Assessment Method and the criteria of the Diagnostic and Statistic Manual of Mental Disorders, 4th Revision. The mean age of 30 patients (73.3% women) was 86.5 ± 5.2 years. Delirium was diagnosed most often on the second and third day of hospitalization. A lot of predisposing and precipitating factors for delirium were identified. There was a significant difference in the melatonin hormone concentration measurement at 12:00 when patients had acute delirium and after its resolution [18.5 (13.8, 27.5) vs 12.9 (9.8, 17.8), p<0.01]. Different patterns of the melatonin hormone concentration were shown in analyses in the subgroups defined according to the patients' diagnosis of dementia. We found that the delirium recovery was, in fact, associated with the alteration of the daily profile of melatonin.
