Examinations of the methods used to power supply of different light sources and their effect on bioelectrical brain activity

Abstract

Objective: The article represents the preliminary study, with the aim of the experiment being to examine whether different types of light sources used commonly in building interiors combined with various color temperature have an effect on EEG activity. The effect of frequency pulsation and color temperature on brain activity in EEG examinations in the beta 2 band was assumed.

Material/participants: Twenty healthy men aged 19-25 years participated in the experiment.

Methods: The research stand was lit by: LED diodes with color temperatures of 3000K, 4200K, 6500K, with the power supplied using the pulse width modulation (PWM) method with the current frequency of 122Hz, linear fluorescent tubes (3000K, 6500K), with the power supplied with the frequency of 50Hz and 52kHz from the electromagnetic and electronic ballasts, and the conventional light bulb, with the power supplied directly from the mains electricity, used as a reference light. System Flex 30 apparatus with TrueScan software was used to record the EEG signal. The examination used two factors (speed and accuracy) of the Kraepelin's work curve to describe changes in work performance for various types of lighting.

Results: The results demonstrate that the use of different types of emission of light and color temperature of the light have an effect on bioelectrical brain activity and work performance.

Conclusions: The highest activity of brain waves concerns the beta band in the frequency range of 21-22Hz, regardless of the type of the light source (LED, fluorescent tube). The methods used to supply power and color temperature of fluorescent tubes do not significantly affect bioelectrical brain activity during "work", but previous lighting with fluorescent tubes during work has an essential effect on bioelectrical brain activity during rest. Regardless of the color temperature, LED lighting with PWM power supply leads to the highest bioelectrical activity (mainly in the range of 21-22Hz) in the brain during work and rest, which might suggests the usefulness of this method of supplying power for everyday work. Incandescent light does not affect the bioelectrical brain activity during work and rest.

Keywords: Color temperature; EEG; Fluorescent tube; LED; Light pulsation.