Study: Coffee unrelated to alertness, Stimulating effects may be illusion

The results are interesting, but there's a methodological limitation the article isn't emphasizing as strongly as it should.

An illustrative analogy: Suppose you organize a group of people who often take painkillers for headaches, and a group that takes painkillers only rarely. You find that headaches of the regular painkiller-takers are no better with their painkillers than the non-painkiller-takers are without painkillers. Can you conclude from this that painkillers have no long-term effects on headaches? You can't, because the reason the first group was taking pain killers in the first place was probably because they have bad headaches, while the second group doesn't. The painkillers just bring them into parity.

The problem is the two groups the coffee study compares were not assigned their subjects randomly. They're made up of people who choose freely to drink or not drink coffee. The fact that regular coffee drinkers are no better with coffee than non-drinkers are without coffee doesn't necessarily mean that coffee has no long-term effect. It could well be that non-drinkers already have endogenously whatever benefits caffeine provides, and drinkers do not, and coffee brings them up to parity.

In other words, the current study has nothing to say on what happens to people when their long-term coffee drinking habits are changed from what they would normally prefer them to be, and so you can't infer much about the benefits or drawbacks of such changes. You could control for this by assigning people randomly two two groups, have one group drink coffee regularly for a few months while the other abstains, and then repeat the experiment performed here. The results of this modified experiment would determine whether current ad-lib drinkers should stop drinking coffee and whether current non-drinkers should start.

The headline is a little misleading. For regular and heavy coffee drinkers, the study suggests that a cup of coffee merely brings the person out of caffeine withdrawal, and does not provide any stimulation. Since caffeine withdrawal makes you groggy and less alert, it means that regular caffeine drinkers have to consume caffeine just to reach the level they would have already been at if they weren't consuming caffeine regularly.

For people who don't currently have a tolerance for caffeine, it most certainly does provide stimulating effects.

It also seems like the study gave participants the equivalent of a single cup of coffee. If you need more than that for your buzz, looks like you'd have been out of luck.

If you drink caffeine, you should probably spend an hour or two at some point learning the basics of how it works.

http://en.wikipedia.org/wiki/Caffeine#Mechanism_of_action

Long story really short - you've got this hormone called adenosine that tells you when you're tired. Andenosine floats around and attaches itself in your brain to an andenosine receptor. As it attaches, you feel tired.

Caffeine is shaped similarly to andenosine, so it sort of "blocks" the andenosine from getting to the receptor. You're still tired, you still need rest, but you don't feel tired. So that's the tiredness-removal effect of caffeine, it's stopping the andenosine from getting to the receptor.

Now, your body kind of minorly panics at this and secretes adrenalin - y'know, adrenalin, like when you get excited or sacred? Yeah, that one. When andenosine gets cut off, your body perks up like something is happening and releases adrenalin. So there's the energy boost.

Over time, your body start naturally producing more andenosine to compensate, hence, you need caffeine just to feel normal. And your body starts to realize that you don't need the adrenalin, so you start to produce less of it when having caffeine. If you've ever gone a while without caffeine and then had a coffee, you remember how off the wall hyper you got? That slowly fades because your body starts producing more andenosine (the sleepy hormone) if you're a habitual caffeine user, and less adrenalin.

There's more to it than that, but that's some of the basics. Wikipedia's got some decent stuff, a few minutes here and there skimming on this sort of thing is time well spent.

I am no coffee drinker, but I'm surprised that they think their results are conclusive based on a single instance of a placebo administered. Especially when the results are so neurological, that surely the brain compensates the first time a placebo is given -- and gradually (like with any neurotransmitter-affecting chemical) gets rid of its self-generating effects.

'Tests on 379 individuals who abstained from caffeine for 16 hours before being given either caffeine or a placebo...'

Seems like -- cue Pavlovian response, but in your brain.... I'd be more impressed if they were given the placebo/caffeine for a week and still performed the same on the tests..

I can sort of see this; if I've already had caffeine, any warm beverage seems to continue the resulting productivity flow. It's nice at night because I can be awake as long as I want to be, but then be able to sleep when I come down from the flow state.

Incidentally, yesterday I decided to take a 200mg caffeine pill. After that, I saw several new colors that I have never seen before. And I solved some problems that had been bugging me for a few weeks, and implemented them, and watched TV, and read a book. And slept well.

Caffeine may be bad for spiders building webs, but I'm not convinced that it's useless (or bad) for humans.

I'd just like to point out that illusions are often as good as the real thing.

If your brain believes you are more alert, chances are, to all intents and purposes, you will be more alert.

What about non-addicts? I very rarely drink caffeine (just midterms and finals, basically) but I'm pretty sure that when I do, the effects are no illusion.

It may also be that it's not just the coffee for some of us. I have a whole ritual early in the morning around making my coffee. I grind the beans, put on the water to boil. And I brew the coffee in my French press. After I've had a couple of cups of coffee at the beginning of the day, I feel really good and ready to start my day. The expectation and enjoyment of that cup of coffee should be factored in.

This article mentions nothing about how they measure alertness. How objectively can this possibly be measured?

It seems to me that the measure of alertness may only be indirectly measured in by task specific performance. So there may be driving alertness, data-entry alertness etc...

On the other hand, even if all the chemical effects are quantifiable, so the measure is "objective", does that really mean anything for different individuals?

Also, for a given task, it may turn out that I need the anxiety producing effects of caffeine just to care enough to perform the drudgery.

Whew! Time for a second cup.

For some weeks after I stopped drinking coffe each time I had a cup of, say, barley coffee (which is caffeine free) I would get a buzz. It's an interesting experiment that demonstrated, to me, the strength of the placebo effect.

So basically, being a coffee drinker I control when I feel alert and when I feel groggy. Sounds good to me. Before I was a heavy coffee drinker I was at the whim of my body's rhythms.

This is a depressing article. I like drinking coffee, and now it turns out that it's making me groggy and un-alert by default.

I think I've noticed this at weekends - I drink lots of coffee at work all week, and then at the weekend I'll maybe desist for a day, and end up not doing anything productive. Then when I have a cup, I am suddenly infused with get up and go. I really need to cut down :-/

Baloney.

My world has just been destroyed.