Spiders on drugs and other things you want to know about the world’s favourite psychoactive substance

Three in four Australians have a cup of coffee a day, at least according to market research commissioned by (you guessed it) a coffee company.

But is such a finding all that surprising? After all, caffeine is the most-consumed psychoactive substance on the planet.

It might even be the most consumed drug of any kind, aspirin being the other contender.

Yes, caffeine is a tried and trusted way to start one’s day.

But kicking the caffeine habit is easier said, than done

That’s because caffeine is remarkably similar in structure to another substance called adenosine.

As well as being one of the essential nucleotide bases that make up DNA, adenosine is a substance responsible for putting people to sleep.

Because of its shape, caffeine can covertly bind with the brain receptors intended for adenosine. When this happens, you’ll probably find it harder to fall asleep after a night time coffee fix. As well as blocking sleep hormones, caffeine can also increase sensitivity to stimulants like dopamine.

But sleep you must, so the brain makes more receptors to try and catch the globs of adenosine that trigger your daily slumber. The more of these receptors, the more caffeine you need to hit the level of perkiness you’re accustomed to.

It’s why some people need two, or three, or four caffeine hits a day to keep going.

Getting off caffeine? Don’t go cold turkey

Caffeine and its effects on people have been studied for decades.

Perhaps the most famous published work looking at caffeine came out of NASA in the nineties.

Here, the toxicity of certain chemicals was investigated by feeding drug-laced droplets to garden spiders and observing the webs they spun.

The reasoning from these researchers? The more deformed a web became, the more toxic the chemical. Here’s what they found happened when comparing caffeine to cannabis, Benzedrine (speed) and chloral hydrate.

Other caffeine studies have been done on bees, though only to view their pollinating performance.

In 1994, a team from John Hopkins University studied how withdrawal affected people whose consumption of caffeine met the then definition of ‘substance dependence’.

Among 16 subjects who met the definition and underwent a double-blind caffeine withdrawal protocol, 82% showed “objective evidence” of caffeine withdrawal.

That manifested itself in one participant spending the afternoon in a dark office with their head on a desk, another not going to work at all, one making costly errors on a production line and, tragically, one cancelling their child’s birthday party.

There’s a probability that you, or someone you’ve met, has said they can’t function without caffeine, and the withdrawal symptoms of fatigue, headaches, brain fog, loss of focus, and a negative dip in mood are best avoided by a gradual reduction of daily intake.

Australia’s healthdirect service suggests 400 milligrams of caffeine consumption a day is safe, and slowly reducing the amount of caffeine you have each day is a good way to avoid the pitfalls of withdrawal.

Here are some caffeine quantities to think about

Source	Caffeine (mg)
Milk chocolate (50g)	10.0*
Original Coke (375mL can)	36.4
Black tea (237mL cup)	45.0*
Diet Coke (375mL)	48.0
Instant coffee (2g serve)	50-90.0*
Red bull energy drink (250mL)	80.0
Espresso (60 mL)	125.0*

Just remember, even though the bar of chocolate or can of Coca Cola might appear to be the ‘healthy’ option on this list, black coffee and tea contain no fats or sugars.

They just happen to pack a bigger caffeine punch.