What caffeine actually does to your brain

http://www.lifehacker.com.au/2010/07/what-caffeine-actually-does-to-your-brain// coffee tea soft drink soda adenosine neuron receptors spinal cord A1 bind adrenaline speed accuracy quality headache menstrual cycle birth control pill half life 6 hours women smokers tolerance hormone serotonin mood enhancer norepinephrine depression fatigue lethargy irritability nausea vomiting /