Caffeine Maintains Arousal Level and Prevents Change of Electroencephalogram Spectral Powers with Time at Rest

Abstract

Caffeine is one of the most commonly used central stimulants. It is frequently used for its mood and performance enhancing effects. The daily caffeine intake of Korean university students and North American adults are approximately 120 mg and 200 mg, respectively. Caffeine increases vigilance and diminishes sleepiness, and administration of these doses stimulates attention and restores performance degraded by factors such as fatigue and boredom. Central stimulating effects of caffeine have been evaluated by quantitative electroencephalography (qEEG) analysis. Although many studies have used qEEG analysis, inconsistencies still remain regarding the effects of caffeine on electroencephalography (EEG) spectral powers. These inconsistencies could be attributed to experimental differences between studies. Many studies have been conducted to clarify the effects of various parameters, such as, dose-dependency, eyes open or closed, and vigilance control. However, recording duration for qEEG analysis has not been well considered. According to multiple sleep latency test (MSLT) studies, sleep latency in normal adults during the day is around 15 min. Considering that the duration of the EEG recordings are generally 10–30 min, sleep can occur during recording and thus EEG rhythms can change. Accordingly, the selection of a part from a recording for qEEG analysis can affect the outcome of studies on the effects of caffeine on EEG spectral powers. In contrast to subjective questionnaires or neuropsychological tests, qEEG analysis has the advantage of being able to provide objective descriptions of temporal changes. Therefore, we examined the effect of caffeine effect on temporal change by qEEG by dividing the recording period into two segments and by comparing the qEEG parameters of