Why does caffeine make me sleepy?

Why does caffeine make me sleepy?

I have never drank a cup of coffee. I am an avid (decaf) tea person who enjoys the occasional chai latte or hot chocolate, but never coffee. Between witnessing my family’s persistent addiction to coffee, my allergy to dairy, the possibility of coffee staining my teeth, and knowing that caffeine is generally not great for you, I never got around to indulging in Seattle’s drug of choice: coffee. On top of the previously mentioned points, I also have a suspicion that caffeine makes me sleepy. 

I have had limited experiences with caffeine but they have all ended in a similar effect. My first encounter with caffeine was in elementary school. I drank some of my dad’s mountain dew in the car and was passed out in the passenger seat before we got to the destination. A couple weeks ago, I saw a new Starbucks drink combo, it was a green tea latte with chai and the tiktokker said it tasted like a dream. Of course I had to try it. I got lucky and found all the ingredients in my kitchen and made myself a cup. I thought about the caffeine in the green tea and chai but I wasn’t concerned. After drinking just a cup (it did indeed taste like a dream by the way) I fell asleep on the couch for two hours, it wasn’t even nighttime. 

Now I know that correlation is not causation and these may have been two isolated incidents but I can’t help but wonder if caffeine is the culprit to my post-beverage drowsiness. Back to my original point: although I am a high school junior with a rigorous academic load, I have yet to turn to coffee to fuel an allnighter. If it could guarantee me a boost of energy, I would down a cup without hesitation but I would rather not risk it inducing unwanted sleep. 

Which brings me to today, mid-winter break, Tuesday, 10:30am. Having no immediate commitments besides a dentist appointment, I think it is the perfect time to try my first cup of coffee, for science of course. As an added bonus, let’s make it black because I hate myself I guess. My first impression of black coffee: GROSS– What possessed my older sister to drink black coffee at 7am every day when she was my age is a question that is yet to be answered. Before drinking the coffee I noted that I feel wide awake, I had woken up a few hours prior and eaten a light breakfast. After adding a tiny bit of sugar to make it drinkable, I finished my cup in about 15 minutes. So far, I don’t feel any different. I will monitor my alertness over the next couple episodes of Naruto.11:00am: I feel relaxed if anything, nothing drastic. 11:30am, thirty minutes after consuming a cup of black coffee: still no effect, again, relaxed if anything. Definitely not more energized or focused than normal. 11:45am: I feel a little sleepy, but to be fair, I almost always feel a little sleepy at any given time. I don’t feel the urge to take a nap but I would have no trouble falling asleep right now. 12:00pm: my eyes definitely feel heavy, but again, I could continue my day without a nap and be fine. 12:45pm: I think I will be concluding this experiment here in fear of running into a normal midday drowsiness. 2 hours and 15 minutes post-black coffee, I feel normal, sluggish at most. Moral of the story: drinking coffee before cramming for a test is a bad idea.

I have scoured the internet on multiple occasions looking for answers for my seemingly pointless issue. All I have found are two theories. One, dehydration. Two, ADHD. 

Let’s explore the first possible reason. According to Healthline.com, caffeine is a substance called a diuretic. What is a diuretic? In short, it is a substance that increases the frequency in which your body produces urine. You pee a lot. Since human urine is 95% water (yes I googled “urine composition”), excessive trips to the bathroom would thus lead to dehydration. According to Healthline.com, the rapid water loss can affect your blood flow and blood pressure in a couple different ways but they all result in your body feeling lethargic and heavy.

The second possible reason, ADHD, is very interesting to me. As far as I know, it has yet to be scientifically confirmed that there is a definite link between ADHD, sleepiness, and caffeine but something tells me that I shouldn’t rule it out quite yet. Unfortunately I have never been screened for ADHD so I cannot speak upon my own experience however I did speak with two of my friends who have ADHD symptoms for some more insight.

 Molly Reagan (‘21) says that they “can have caffeine,” redbull is their drink of choice, “and go straight to sleep after, no matter how much [they] have.Caroline Valley (‘22) tells me that on the days that she takes her ADHD medication and drinks caffeine (usually an iced black tea or matcha), she feels super hyper and energized but on the days that she skips her meds and drinks caffeine, she feels relaxed if anything. This would make sense because according to Healthline.com, caffeine and ADHD medications are both stimulants. They both reduce the size of blood vessels which then reduces the rate of blood flow causing them both to have similar effects. Wild, right?

 In addition, they both raise dopamine levels. People with ADHD naturally have lower dopamine levels than other people so their medication helps raise their dopamine to a similar level of someone without ADHD. So when Valley has both caffeine and her ADHD meds in her system, her dopamine levels are extra high. Then on days where she only drinks coffee, her dopamine levels rise to a level that is comparable to when she takes her meds, making her relaxed or not noticeably any different. The key is, two stimulants at the same time equals energized/hyper and one stimulant equals relaxed/baseline (although this can be different for different people). 

Reagan also tells me that their caffeine withdrawals can sometimes be soothed with their ADHD meds: “if I don’t have caffeine, I will feel real effects from it immediately like poor mood, fatigue, and irritability— all symptoms my adhd meds also counter.” Reagan’s experience seems to further confirm the theory that ADHD medication and caffeine have similar effects. However, that is not to say that anyone should be self medicating their ADHD symptoms with a Starbucks drink, Reagan explains that “3 years before [they were] diagnosed, [they] developed an unhealthy dependency on caffeine. In this relationship caffeine did not give [them] energy, but rather kept [them] feeling ‘normal’. ADHD medications are much more effective, safe, and accurate. 

As for my question: “why does caffeine make me sleepy?”, the jury is still out.