How long does Rockstar Energy
stay in your system?

A 16 oz Rockstar contains about 160 mg of caffeine, the same as a Monster and roughly double a Red Bull. Like other large energy drinks, the size and sweetness encourage fast consumption, delivering the full dose quickly rather than spread out the way a hot coffee usually is.

From 160 mg, the 5-hour half-life leaves about 80 mg after five hours and 40 mg after ten. A can finished after lunch can still leave a noticeable amount circulating at bedtime for average and slow metabolizers alike.