If you’ve had more than 250 mg of caffeine (two to three cups of brewed coffee) and experienced five or more of the following symptoms, says the guide, you’ve probably been caffeine-buzzed: restlessness, nervousness, excitement, insomnia, flushed face, diuresis (having to pee a lot), gastrointestinal disturbance, muscle twitching, rambling flow of thought and speech, tachycardia or cardiac arrhythmia, periods of inexhaustibility or psychomotor agitation (unintentional motion, say, rapidly bouncing one leg).

This disorder, as it’s described in both the older DSM-IV and new DSM-5, falls under the heading “Caffeine-Related Disorders,” but in DSM-5, that section includes a new entry: caffeine withdrawal. According to DSM-5, symptoms of caffeine withdrawal include fatigue, headache and difficulty focusing.