It’s estimated as many 90 percent of American consume caffeine at some point during the day: maybe coffee, tea, soda or energy drinks or various foods. Caffeine has benefits, but it can be harmful if we consume too much. Sam Baker talked about this in a KERA Health Checkup with Dr. James Bibb of UT Southwestern Medical Center.
Dr. Bibb: Caffeine’s a product of biosynthesis in plants. It’s actually called trimethylxanthine.
Sam: You called it a drug. Is it addictive?
Dr. Bibb: Caffeine is addictive and it targets all the same pathways and circuits in the brain that are targeted by more severe addictive drugs of abuse. So, it is clearly a drug that can be addictive and one can become a dependent on. And if one stops taking it, once one is used to taking it, it’s possible you can go through withdrawal.
Sam: This depends on how much you consume, I guess?
Dr. Bibb: Well, I think it probably varies from one person to another. A standard amount that people consume a day is two cups of coffee, and that’s about 300 milligrams of caffeine.
Sam: Are there benefits, though, to consuming caffeine?
Dr. Bibb: Caffeine has a number of effects. It’s a vasoconstrictor and it targets the circulatory system. It also targets the brain, as I mentioned earlier, and it causes us to be more aroused, more vigilant, more alert.
Sam: But how can it work against us?
Dr. Bibb: Well, if you take to much you can have tremors. You can have anxiety, difficulty concentrating, and so there’s a point at which people don’t want to take any more caffeine.
Sam: But if you try to stop consuming it, then aren’t we in for headaches or something?
Dr. Bibb: One of the side effects is headaches. It can also cause more severe side effects like sort of depression-like symptoms where it’s hard to have energy; it’s hard to make the transition from rest to activity. And you can have difficulty functioning if you’re going through severe withdrawals and that lasts about nine days.
Sam: If you go without sleep or (get) too little sleep, you begin to build up what’s called sleep debt. I’ve read that with caffeine, it can take a few hours to process out of your body. If you consume too much or do it daily or whatever, do you build up sort of a caffeine debt?
Dr. Bibb: What we think sleep debt is is a buildup of a building block of an energy molecule in the body, ATP. Its building block is adenosine. As we go through our wakeful day, we build up adenosine. And then adenosine at some point gets to very high levels and it binds to adenosine receptors, and that is thought to help us make the transition from being awake to asleep. What caffeine does is block those adenosine receptors and prevents adenosine from binding them. So we have difficulty making this transition from wakefulness to sleep and, also, we stay more alert – which is another function of adenosine is to kind of lower the volume and tone everything down. So, do we build up a caffeine debt and does it take time to clear it out? It takes about six hours for the body to clear out caffeine. And so if you drink coffee at three in the afternoon, there’s a good chance you could trouble falling asleep at night. So that’s why most of us drink coffee in the morning, but we tend to resist it after lunch.
Sam: You’re a neuroscientist. Why are concerned with this subject of caffeine?
Dr. Bibb: One of the things I’m most fascinated by is how synapses are able to respond to environmental experiences, and these synapses make up your circuitry. And it basically serves as the method by which events are recorded and we’re able to learn things that happened and then recall them. Caffeine facilitates that process. It increases the activity of neurons and it can facilitate learning.
Dr. James Bibb is an associate professor at UT Southwestern Medical Center.
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