Physiology & Behavior, Vol. 256, No. 1, November 2022
Caffeine Suppresses Alpha Activity, Physiology & Behavior, Vol. 256, No. 1, November 2022. Barry et al. ([4, 5])
Demonstrated an association between a global decrease in EEG alpha power during
and eyes-closed resting state and an increase in arousal ~ 30 minutes after caffeine consumption in
healthy young populations. This motivated the present study by Amornpan Ajjimaporn, Prapan
Noppongsakit, Papatsorn Ramyarangsi, Vorasith Siripornpanich, and Rungchai Chaunchiaiyakul,
published in Physiology & Behavior, Vol. 256, No. 1, November 2022.
The effects of low dose caffeine consumption, administered in the morning, on brain wave activity were
investigated in 25 healthy young men university students in Thailand with an average age of 21 years
(±standard deviation was 2 years). Their height was 176 ±7cm, body mass 69.6 ±8.5 kg, % body fat
15±4%, body mass index 22.5 ±1.3. Participants received a placebo (PLA) or a 50 mg caffeinated drink
(CAF) under randomized double-blind crossover conditions, with 1 week between conditions.
Participants were low or mild-habitual caffeine users (i.e., they consumed 1-2 or fewer cups of caffeinated
coffee or tea, or 1 can of caffeinated coca-cola equivalents daily). They were non-smokers, recreationally
active, and they did not take dietary or sports nutrition.
Brain wave activity, EEG, was measured along the midline of the brain at the Pf z (Prefrontal), C z
(Central), P z (Parietal), and the O z (Occipital) regions of the brain. Brain wave activity was measured
before and 30 minutes after drinking a 50 mg caffeinated drink. The intent was to see how the caffeine
influenced the brain waves. The EEG analysis revealed a highly significant main effect of time for the
delta waves over the P z (F2,48 = 14.11, ηp²=0.19, p<0.0001) and O z electrodes (F2,48=4.74, ηp²=0.32,
p<0.0001). The EEG analysis also revealed a highly significant main effect of time for the Alpha waves
over the Fp z (F2,48 = 4.74, ηp²=0.17, p<0.01) and C z electrodes (F2,48=5.50, ηp²=0.20, p<0.01) and the
P z electrode (F2,48 = 7.31, ηp²=0.23, p<0.002) and the O z electrode (F2,48=4.64, ηp²=0.32, p<0.001).
This study investigated the acute effects of a single dose caffeinated drink (50 mg of caffeine) on brain
wave activity in healthy university student South-East Asian males. The main findings demonstrated that
30 minutes following caffeine drinking, the mean absolute power of the Alpha waves appears to diminish
and that a similar pattern, compared to the placebo, is also exhibited in the delta wave activity.
The result of the present study demonstrated that, as compared to a placebo drink without caffeine, EEG
Alpha waves deactivated (became weaker and with less power) over a wide region of the brain extending
all the way from the front of the brain to the back of the brain (Frontal, F z , Central, C z , Parietal, P z and the
Occipital, C z ). An association between attenuated Alpha activity and caffeine consumption suggests that
commercial drinks even with low caffeine dose, the equivalent of an 8-oz cup of instant coffee, a single 1-
oz shot of espresso, an 8-oz cup of black tea, a 12-oz can of soft drinks, etc. can significantly reduce a
person's Alpha brain wave power all across the head from the front of the head to the back of the head.
The authors would like to thank Prof. Mark Williams, Institute of Sport, Nursing and Allied Health,
University of Chichester, the United Kingdom, for his editorial assistance on this manuscript.
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