Caffeine is a drug where you must consume it habitually, or never at all, or else face regular headaches. Like others mention here, I had aura migraines nearly

Caffeine is a drug where you must consume it habitually, or never at all, or else face regular headaches. Like others mention here, I had aura migraines nearly each week, which bad enough to cause vomiting which were seem to be getting worse with age. It took me a while, but I eventually linked it to caffeine withdrawal. Mind you, not even complete withdrawal would still cause me headaches (eg. If I had 2 cups of coffee one day but normally 1 cup otherwise, I'd still get a headache). Quit 10 months ago, and have had only 1 headache since, and feel slightly less anxious. That said, there's also been studies suggesting that it affects motivation in subtle ways (e.g. productive people become more like slackers). But who knows how valid such studies are, given their makeup, and how often studies seem to oppose each other. But then again, I'd imagine almost all drugs affect us in subtle ways we almost never realize, especially after having seen multiple people become abusive - some after having alcohol, others amphetamines - only to deny that they seem like a completely different person when compared to them being sober.