Table of Contents
Journal of Hormones
Volume 2013 (2013), Article ID 236325, 4 pages
http://dx.doi.org/10.1155/2013/236325
Clinical Study

Salivary Melatonin Concentrations in a Sitting and a Standing Position

1Faculty of Design, Kyushu University, Fukuoka 815-8540, Japan
2Graduate School of Design, Kyushu University, Fukuoka 815-8540, Japan

Received 28 May 2013; Revised 19 August 2013; Accepted 27 August 2013

Academic Editor: Tullio Florio

Copyright © 2013 Tomoaki Kozaki et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This study aimed to examine differences in salivary melatonin concentrations between the sitting and standing positions. Ten subjects (age range: 20–22 years; 5 males and 5 females) participated in the study and provided written consent. In the sitting condition, the subjects sat on a chair from 23:30 h to 1:00 h, whereas in the standing condition, the subjects sat on a chair from 23:30 h to 0:30 h and stood on the floor from 0:30 h to 1:00 h. Saliva samples were obtained at 0:25 h and 1:00 h from all subjects. The experiment was performed under a dim light condition (<10 lx). No significant differences were observed in melatonin concentrations between the two positions at 0:25 h; however, melatonin concentrations in the standing condition were significantly greater than those in the sitting condition at 1:00 h. These results show that melatonin secretion is significantly greater in the standing position than that in the sitting position.