You can't see how drinking something with caffeine is going to boost someone's "energy"?
It's not the Caffeine in the drink that's the main incredient. Phenylalanine, Taurine, Glucuronolactone, Malic Acid, Tyrosine, and Citicoline are also present to supposedly boost alertness. The Caffeine is the quickest-acting of the list, and I'm suspect of the Taurine and Phenylalanine as being huge contributors to "energy" per se, but it seems the drink relies on a huge B-vitamin mix and the aforementioned ingredients to promote alertness and awake-ness.
Does it work? Well, it does on me (with qualifications). I grabbed one a couple months ago, skeptical of the stuff but beginning an all-nighter on some stuff at work, so I picked one up as a test. There's no real "energy" boost if what you're looking for is the caffeine burst or jitters, but it certainly helped keep off the 3AM sag from tired-ness being up all night. In fact, if I had to gauge its effects for a time frame of effectiveness, I'd say I was pretty good to go for about six or seven hours into the all-nighter before I started feeling the normal fatigue from being up way too long without sleep. The 5-Hour shot isn't going to give someone any boost above their normal operating condition, but if taken prior to or during a period where fatigue is setting in, the drink helps keep the fuzzy edges from closing in and hampering your alertness-- to a degree. It's not some kind of magical potion, and I'd strongly urge someone to follow the company's suggestion of taking a half-bottle first and saving the rest for later if needed, but I can speak to its efficacy with my own experience. Definitely worth the $3 for the night.
Just bear in mind that while their "energy" name and advertising is all well and good, what you get from it isn't "energy" as much as it is "sustained alertness" and possibly (for some) a bit of flushed skin due to a high dose of Niacin in the drink. It's not a substitute for real energy-producing fuel for the body-- meaning food, particularly the healthy kind. For those who might be experiencing a case of the "blahs" some morning or who feel like they didn't quite get enough sleep the previous evening, it'll help you out (some) in that you'll feel less "blah" and able to operate at your normal level of alertness. It doesn't give you anything that your body isn't already capable of or doesn't already have, so expecting a rush of energy is going to lead to disappointment with this stuff. It works, but not like you'd expect from its advertisements, though I'm sure they have a marketing department who'd love to correct me for my saying so. Use at your own risk, and be sure to read the print on the bottle (even the small stuff) before giving it a glug.
Note: this stuff has a
huge shot of B-vitamins, including more than %8,000 higher than the daily recommended value of B-12 in just one shot. It's not something I'd recommend as a regular supplement for a normal, healthy adult (and not at all for children), because it's not meant for that purpose. People who are older or who have B-12 or B-6 deficiencies (not typical or likely if your reaction is "I don't know") might benefit from it, but there are far more reasonable medical avenues to address such things.