Melatonin improves sleep-wake patterns in psychomotor retarded children

Abstract

Five children with severe psychomotor retardation (mean age 8.2 ± 3.6 years) and irregular sleep-wake patterns underwent 1 week of wrist actigraphic monitoring before and after treatment with 3 mg melatonin. Three underwent multiple measurements of urinary sulfatoxymelatonin levels. Urine sulfatoxymelatonin levels were abnormally low, without any significant day/night differences. Melatonin treatment increased nighttime sleep from 5.9 ± 0.8 to 7.3 ± 0.5 hours (paired t test, P < 0.01) and sleep efficiency from 69.3% ± 6.2% to 88.3% ± 2.3% (P < 0.01). Daytime sleep decreased from 3.2 ± 1.2 to 1.7 ± 1.2 hours (P < 0.05). Thus, no change in 24-hour total sleep time (9.1 ± 1.5 vs 9.0 ± 1.6 hours) occurred. Administration of 3 mg melatonin to five severely psychomotor retarded children resulted in a significant improvement in their sleep-wake patterns.

Introduction

Melatonin is a neurohormone produced by the pineal gland, normally secreted exclusively during darkness. Recent research has revealed that melatonin has a dual effect: sleep promotion and circadian pacemaker phase shifting [1]. Sleep disturbances among institutionalized mentally retarded children are well documented [2], [3], but it is not known whether these are related to melatonin secretions. Zhdanova et al. [4] reported that 0.3 mg melatonin improved the objective and subjective sleep quality of children with Angelman syndrome. In three of their patients, they observed delayed melatonin peaks. Administration of 2.5-5 mg melatonin to multiply disabled children with severe sleep disorders resulted in substantial improvement in their sleep as reported by their caregivers [5]. The most significant improvement was observed in blind children who probably had circadian rhythm disorders [5]. The beneficial effects of melatonin were also reported in an insomniac child with a pineal tumor [6] and in children with Rett syndrome [7] and tuberosclerosis [8]. Recently, we reported the improvement in sleep in an institutionalized psychomotor retarded child after melatonin administration [9]. For the present study, we sought to determine whether the administration of melatonin could influence the sleep-wake schedule of psychomotor retarded children with erratic sleep schedules. Here, we report the complete results of this study. The study was approved by the chairman of the Rambam Medical Center’s committee for human subjects’ research.