Effect of Melatonin Administration on Sleep Quality in Sulfur Mustard Exposed Patients with Sleep Disorders

Sulfur mustard (SM) is a toxic agent that targets several tissues. It is the leading cause of persistent lung disease, progressive deterioration in lung function, and mortality among injured patients. Disturbed sleep and poor quality of sleep are common in SM-exposed patients with chronic respiratory problems. Melatonin is an alternative medication that has been widely used to treat poor sleep quality caused by several specific conditions. This study aimed to evaluate the efficacy of melatonin administration in improvement of sleep quality in SM-injured patients. In this randomized, double-blind and placebo-controlled trial study a total of 30 SM-exposed male patients were recruited. Patients received 3 mg melatonin (N = 15) or placebo (N = 15), orally in a single dose, 1 h before bedtime for 56 consecutive days. Sleep quality was evaluated by Pittsburgh Sleep Quality Index (PSQI); daytime sleepiness was measured by Epworth Sleepiness Scale (ESS), and the risk of obstructive sleep apnea was determined by STOP-Bang questionnaire. Compared with placebo, melatonin administration significantly improved global PSQI score, particularly sleep latency (P = 0.03) and subjective sleep quality (P = 0.004). Mean of global PSQI score was declined significantly (P = 0.01) from 10.13 ± 3.44 to 6.66 ± 3.08 in melatonin group. No differences in ESS and STOP-Bang scores were observed between two groups. Melatonin was effective in improving global PSQI score and sleep latency, but not daytime sleepiness and obstructive sleep apnea in SM-exposed patients. Further long-term studies involving larger number of patients are needed before melatonin can be safely recommended for the management of sleep disturbances in these patients.