(Note: This article is from the archive and was written c. 2022.)
Caffeine is the most used drug in the world. It is a stimulant that works primarily by blocking adenosine receptors.
Some of you may remember cellular respiration from biology. This is where our cells take glucose (food) and use it plus water and oxygen to create energy in the form of ATP — adenosine triphosphate. This and other adenosine compounds are used to cause actions in cells. Need to walk a protein to another part of the cell? Bam! ATP to the rescue. Reading RNA and need to build a protein? Bam! ATP makes it happen. Need to trigger a Rube Goldberg style intercellular cascade? Bam! ATP can do that.
And as the cells in your body work, as you burn through your glucose stores to create ATP to make actions happen, you’ll have a build up of adenosine. All this adenosine then will connect with adenosine receptors, telling your body you’ve been busy and should get some sleep.
…and this is where caffeine comes in.
Caffeine puts the brakes on that process. It antagonizes the adenosine receptor, meaning it blocks or dampens them from functioning correctly. So you have all this adenosine building up, ready to tell your body you need some rest, and caffeine interferes with the message from getting through. This tricks your body into an alert state, and staves off sleep.
But that’s not all caffeine does. It has downstream effects on serotonin, dopamine, and norepinephrine. These are powerful mood hormones, and also the primary hormones found in the original antidepressants. Sure enough, studies show that caffeine intake can help with mild depression.
One of the ways this happens is that these adenosine receptors are linked to dopamine receptors. When the adenosine binds to its receptor, telling the body you’ve been working and need to rest, it kicks the dopamine off the adjacent dopamine receptor, so the body gets less of the dopamine response. But when we intake caffeine, the adenosine receptor is blocked, so the dopamine continues to activate its dopamine receptor, and we keep getting the infamous “dopamine hit.”
Of course, there’s a catch. Too much dopamine can increase irritability. Caffeine can also exacerbate anxiety. It does this partially through hindering sleep; partially through keeping body cortisol — stress hormones — high; and partially through inhibiting our body’s GABA system, which is our body’s natural way of relaxing.
In other words, a little caffeine can help fight against subclinical depression, too much caffeine can increase your anxiety and irritability.
Caffeine also seems to potentiate acetylcholine, which is tied to increased memory and learning. Oh, and increased urination, too. Doesn’t help that it’s generally consumed as a liquid, either.
Other benefits to drinking coffee seem to be lowered risk of dementia, lowered risk of Parkinson’s disease, and possibly even lowering incidences of type 2 diabetes.
On the other hand, it is a mild contributor to hypertension, can increase episodes of acid reflux largely due to its acidity when imbibed as coffee, and can be harmful in pregnancy if not kept at low doses.
So what to do? The answer for most people seems to be just keep your consumption low. 1–2 cups of coffee in the morning will equate to about 100–200 mg caffeine total, assuming about 100 mg of caffeine per 8 oz cup. Caffeine has an average half life of 4–6 hours. So it takes the average person between 20 to 30 hours to get caffeine out of their system. That’s a full day including the night. For this reason, it’s better not to have coffee as the day progresses, but to keep it to early parts of your day. Additionally, a coffee-free day here and there to make sure your body gets it out of the system, that it’s not accumulating, is a good idea if you find your anxiety levels getting too high.
Consider also switching to tea. Green tea especially has been found to have incredible health benefits, from being more calming due to included l-theanine compounds to helping reduce blood sugar levels. It also has less than half the amount of caffeine compared to an average cup of coffee.
If you stop coffee altogether, be aware of rebound headaches if you were a chronic coffee consumer. We mentioned that caffeine has downstream effects on norepinephrine, and norepinephrine is a vasoconstrictor. This causes your blood vessels to get smaller. If you drink a lot of coffee, your body will use mechanics to compensate and get your vessels a little larger again. Then, when you suddenly stop drinking coffee, there is no longer the extra norepinephrine causing the vasoconstriction, but the balancing mechanics countering the norepinephrine will still be in place, meaning your vessels will get even larger…
…and you’ll get a headache from the extra pressure in your brain.
So take it easy.
At the end of the day, you know your body. But watch out for negative effects from excess caffeine consumption, usually found in the form of poor sleep, increasing anxiety, and/or increasing irritability. If that is happening to you, consider cutting down and replacing much of your coffee habit with teas. And consider having the occasional caffeine-free day.
PS~ If you want to nerd out a bit, caffeine is metabolized by the CYP1A2 system, and some researchers are looking at genetic links with consumption and health benefits.
