Effect of Melatonin on the Human Electrocardiogram and Simple Reaction Time Responses

Abstract

It has been suggested that melatonin may have therapeutic potential for alleviating jet lag. In an attempt to define further the effects of low pharmacological doses of melatonin on the human body, 5 mg of melatonin was given orally to one subject in a blind experiment. The electrocardiogram (ECG) was recorded together with simple reaction time (SRT) responses over a 5-h period after taking melatonin. The main part of the project was carried out under artificial domestic lighting conditions and involved ten evening sessions. Microprocessor analysis of the ECG of one subject clearly showed that melatonin had the effect of lengthening the RR interval, that between the peak of the P wave and the onset of the R wave, and the interval between the onset of the R wave and the peak of the T wave. A model to explain the cubic curve, which was fitted by regression analysis to the data, implies that the natural evening increase in melatonin may also increase these intervals. The results suggest that melatonin may affect both the phase and the amplitude of the observed ECG phenomenon. Analysis of more than 40,000 SRT responses to both visual and auditory stimuli implied that these responses might also be lengthened by melatonin. Frequency histograms of the responses and observations on premature and missed responses were not able to reproduce the results of other workers who found that higher doses (240 mg) of melatonin decreased the number of incorrect responses to simple reaction time tasks.

Melatonin and sleep in humans

“…As melatonin does not appear to exert its hypnotic effects via endocrine mediators, recent studies have shifted their attention to the chronobiological properties of melatonin [Arendt et al, 1987[Arendt et al, , 1988Dahlitz et al, 1991;Folkard et al, 1990;Palm et al, 1991;Petrie et al, 1989;Sack et al, 19911. It has already been argued that melatonin's effect on sleep may be related to the phase shifting effects on the circadian system [Redman et al, 19831.…”

“…However, at night-time, when endogenous melatonin levels are higher, additional sedative-hypnotic effects over and above the normal nocturnal elevation in sleeppropensity are not observed. In general, melatonin administration during the sleep period has been reported to facilitate sleep only in subjects subjected to artificially induced insomnia [Waldhauser et al, 19901, or insomnias related to chronobiological disorders [Arendt et al, 1987[Arendt et al, , 1988Dahlitz et al, 1991;Folkard et al, 1990;Palm et al, 1991;Petrie et al, 1989;Sack et al, 19911.…”

Serum melatonin concentrations in coronary heart disease patients with hypercholesterolaemia

“…[8][9][10][11][12][13] Op metaboliese vlak inhibeer melatonien cholesterolsintese in menslike leukosiete.…”

Pineal Effects on Adrenal Medulla, Area postrema and Brain Water Content in Relation to Intracranial Surgery

“…In this relation, it should be men tioned that the existence of melatonin recep tor in the suprachiasmatic nuclei, which is a center of circadian rhythms in the body, has been reported in many animal species includ ing man [5, 7, 9], In addition, direct effects of timed release of melatonin on almost all cells in the body have also been postulated to be involved via intracellular Ca2+-related mecha nisms in the circadian timing mechanism [33], Concerning the biological timing, pineal effects on the heart rate, the seasonal rhythm and aging have also been considered [2,[34][35][36][37] Morphological components and their indi cators, shown in parentheses, in group 1 in volve the following: small clear vesicles in the preganglionic nerve endings (numerical den sity); cell, cytoplasm, nucleus and nucleolus (size); mitoses (frequency); mitochondria in the whole cytoplasm (number); small clear vesicles in the Golgi apparatus (numerical density); mitochondria in the perivascular zone of the cytoplasm (numerical density); exocytoses in the plasma membrane facing the perivascular space (frequency of exocytosis-positive cell profiles and number per unit area or cell).…”

“…In this paper, we aimed to clarify (1) changes in functional structures of the adrenal medulla following pineal manipulation; (2) possible central route and mechanisms of pi neal influences on the adrenal medulla; (3) whether and how the pineal gland and the autonomic nervous system including the ad renal medulla participates in the control of the brain circulation either under physiologi cal conditions or in response to intracranial surgery, mainly from data of our laboratory.…”