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.