[Vegetative cardiac rhythm regulation as a function of the morning melatonin levels in teenagers-northerners on a background of mental effort]

Abstract

Seventy normal 12-15 y.o. teenagers in the Arkhangelsk oblast of Russia (in latitude 61 north) were investigated in the pubertal period (June, September, December). Immune-enzyme analysis was used to determine melatonin levels in blood serum at 8.30-9.30 a.m. In the daytime, cardiac rhythm variability was assessed on a background of mental calculation. It was shown that morning melatonin in blood serum of teenagers-northerners may be indicative of sympathetic cardiac rhythm regulation, particularly during mental effort. In June (the longest light period) the vegetative regulation had a minimal effect on mental effort. Dependence of the sympathetic activity on the level of morning melatonin in teenagers was conspicuous in September when the light period shortens.