Nocturnal serum melatonin levels in sulfur mustard exposed patients with sleep disorders

Abstract

Background: Sulfur mustard (SM) exposure causes respiratory disorders, progressive deterioration in lung function and mortality in injured victims and poor sleep quality is one of the most common problems among SM-exposed patients. Since melatonin has a critical role in regulation of sleep and awareness, this study aimed to evaluate the serum melatonin levels in SM-injured subjects.

Methods: A total of 30 SM-exposed male patients and 10 controls was evaluated. Sleep quality was evaluated by the Pittsburgh Sleep Quality Index (PSQI); daytime sleepiness was measured by the Epworth Sleepiness Scale (ESS), and the risk of obstructive sleep apnoea was determined by the STOP-Bang questionnaire. Polysomnography (PSG) and pulmonary function tests (PFTs) were also available. Nocturnal serum melatonin levels were measured using an ELISA kit.

Results: The mean of PSQI, ESS and STOP-Bang scores in patients (11.76±3.56, 12.6±3.03 and 5.03±1.09, respectively) were significantly (p<0.01) higher than those in the controls (2.78±0.83, 4.69±1.15 and 1.18±0.82, respectively). PFTs also showed declined respiratory quality in SM-patients. There was a significant difference regarding the PSG results between patients and controls (p<0.01). The mean of nocturnal serum melatonin levels in patients (29.78±19.31 pg/mL) was significantly (p=0.005) lower than that in the controls (78.53±34.41 pg/mL).

Conclusions: Reduced nocturnal serum melatonin and respiratory disorders can be the reasons for poor sleep quality among these patients.

Trial registration number: IRCT2015092924267N1, Pre-results.

Keywords: Chronic pulmonary problems; Nocturnal melatonin; Sleep quality; Sulfur mustard.