You can’t have tea before bed or you’ll be awake until the wee hours, but your spouse claims it puts them to sleep. Your co-worker and sister both drink roughly the same amount of caffeine per day, but one is always energetic while the other drags through the day.
Basically, caffeine affects some people more than others. Why? Many reasons, but apparently our genetics and biorhythms have a lot to do with it.
While conclusive evidence may still be a pipedream, there are tons of fascinating studies to keep your wheels turning.