Urinary levels of 6-sulphatoxymelatonin and their associations with sleep disorders and behavioural impairments in children with autism spectrum disorder

BACKGROUND: Autism spectrum disorder (ASD) is a neurodevelopmental condition associated with sleep disturbances that may result from abnormalities in melatonin production. The correlations of melatonin levels with the severity of sleep disorder and/or severity of ASD were reported. OBJECTIVES: To evaluate urinary levels of the melatonin metabolite, 6-sulphatoxymelatonin (aMT6s), in children with ASD, and their associations with sleep abnormalities and behavioural impairments. METHODS: Study involved 77 children with ASD and 84 controls aged 2.5-15.5 years. Sleep disorders were assessed by Children's Sleep Habits Questionnaire. Morning and afternoon levels of aMT6s were determined by radioimmunoassay method. Urinary creatinine levels were assessed by an enzymatic method. RESULTS: The urinary aMT6s/creatinine values indicate that the night-time melatonin levels are significantly lower in ASD than in controls, but there are no significant differences in the daytime levels. In the ASD group, on average, a 6.8-fold difference between night-time and daytime values of urinary aMT6s/creatinine was found, whereas for the controls a 12.5-fold difference was observed, indicating a lower night-time increase in melatonin levels. In ASD group, the difference in night-time-daytime aMT6s/creatinine value correlated with some types of sleep problems, but not with the severity of ASD. CONCLUSION: The results indicate that in ASD there are differences in the patterns of melatonin secretion that may be associated with sleep impairment (Tab. 4, Fig. 2, Ref. 28).