A review of the recent literature shows the role of caffeine in the physiology, mood, and behavior of persons to be a complex one including changes in arousal, anxiety, and performance. Questions are raised as to what degree the physiological effects of caffeine are due to central nervous system stimulation and/or result from the release of catecholamines. Anxiety resulting from both high levels of caffeine (caffeinism) and caffeine withdrawal plus an association between caffeine and depression are discussed. Performance effects are mixed, with both increases and decreases reported. Effects on mental tasks are related to personality variables. The possible role of differences in initial sensitivity, adaptation to caffeine, and/or interactions with nicotine and alcohol is discussed. The present paper reviews these studies, discusses their implications for both clinical and experimental work, summarizes the major unresolved issues, and makes suggestions for new and continuing areas of research.

This study aimed at studying the effect of electromyography biofeedback (EMG & EEG) training on the tension and migraine headaches of migraine patients in Ahvaz. The sample of the study included 30 participants who were selected through simple random sampling, and were assigned to experimental and control groups. The research design was pre-test, post-test with a control group. The participants were pre-tested using the scales of tension headache (HIS) and migraine headache. The experimental group underwent a biofeedback EMG and EEG treatment for twenty 45-minute sessions (in two months). Then, after the treatment both groups were post-tested. To analyze the data, a multivariate analysis of covariance (MANCOVA) was conducted. Results showed a significant difference between the experimental and control group, that is, electromyography biofeedback reduced the tension and migraine headaches.

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