35th Annual International Conference of the IEEE EMBS 2013
Watchara Sroykham, Student Member, IEEE and Yodchanan Wongsawat, Member, IEEE
Abstract— Melatonin is a circadian hormone transmitted via suprachiasmatic nucleus (SCN) in the hypothalamus and sympathetic nervous system to the pineal gland. It is a hormone necessary to many human functions such as immune, cardiovascular, neuron and sleep/awake functions. Since melatonin enhancement or suppression is reported to be closely related to the photic information from retina, in this paper, we aim further to study both the lighting condition and the emotional self-regulation in different lighting conditions together with their effects on the production of human melatonin. In this experiment, five participants are in three light exposure conditions by LED backlit computer screen (No light, Red light (~650nm) and Blue light (~470nm)) for 30 minute (8-8:30pm), then they are collected saliva both before and after the experiments. After the experiment, the participants are also asked to answer the emotional selfregulation questionnaire of PANAS and BRUMS regarding each light exposure condition. These results show that positive mood mean difference of PANAS between no light and red light is significant with p=0.001. Tension, depression, fatigue, confusion and vigor from BRUMS are not significantly changed while we can observe the significant change in anger mood. Finally, we can also report that the blue light of LEDbacklit computer screen significantly suppress melatonin production (91%) more than red light (78%) and no light (44%).
I. INTRODUCTION Melatonin or N-Acetyl-5-methoxytryptamine is a circadian hormone. It is rhythmically produced by the pineal grand in the brain with a low level during daytime and a high level during nighttime. The level of melatonin rises during the evening (8-11pm). It will reach the peak level between 2- 4am and decrease to the baseline level during late morning (8-10am). This mechanism is controlled by the suprachiasmatic nucleus (SCN) which is inhibited by light and is stimulated by darkness. Melatonin is also known as a hormone necessary to many human functions such as immune, cardiovascular, neuron and sleep/awake functions. In recent, technology development has led to energysaving and effective electronic devices. The Light-Emitting Diode (LED) is one of those. It is widely used in display of This project is supported in part by the government funding of Mahidol University. W. Sroykham is with the Department of Biomedical Engineering, Mahidol University, 25/25 Putttamonthon 4, Salaya, Nakornpathom 73170 Thailand and with Center for Biomedical Instrument Research and Development, Institute of Molecular Biosciences,Mahidol University, 25/25 Putttamonthon 4, Salaya, Nakornpathom 73170 Thailand(e-mail: watchara.sro@mahidol.ac.th). Y. Wongsawat is with the Department of Biomedical Engineering, Mahidol University, 25/25 Putttamonthon 4, Salaya, Nakornpathom 73170 Thailand (corresponding author, phone: 66-82-889-2138 Ext 6361; fax: 66- 82-889-2138 Ext 6366; e-mail: yodchanan.won@mahidol.ac.th). electronic device such as smart mobile phone, television, desktop computer, notebook computer and tablet. However, the light form this device can suppress human melatonin production. Recently Studies, Wood et al (2013) showed that melatonin production can be suppressed after 1-2 hours by tablet with blue LEDs [1]. Cajochen et al (2011) showed that LED-backlit computer screen can significantly suppressed human melatonin production more than a non-LED backlit computer screen [2]. Furthermore, Figueiro et al (2011) showed that light from cathode ray tube computer screen can slightly suppressed human melatonin production and has suggested that the light from electrical devices at nighttime can suppress human melatonin production [3]. Lewy et al also showed that melatonin secretion in human can be suppressed by artificial light [4].
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