Caffeine usage affected by complex hormone processes

Finals are coming up and everyone is starting to get stressed, including myself. There is too much to do and not enough time—honestly, I feel an all-nighter or two may be in my future. So what is it that many Vassar students will turn to for support? You’ve guessed it: coffee! That extra caffeine can come in handy during times of need, such as study week and finals, but at what time of day should we drink coffee?

Well, according to Steven Miller, a neuroscientist at the Uniformed Services University of the Health Sciences in Bethesda, Maryland, the most effective time for students to drink coffee is between 9:30 and 11:30 a.m. It is between these times that natural cortisol levels drop. Cortisol is a steroid hormone and its production is strongly related to alertness. Therefore, it is ideal to consume caffeine when cortisol levels are low. (NeuroscienceDC, “The best time for your coffee,” 10.23.2013)

The peak levels of cortisol in our bodies, or rather the times that it is not best to consume coffee, are between 8 and 9 a.m., 12 and 1 p.m., as well as between 5:30 and 6:30 p.m. An article published in The Daily News on these findings by Miller also warns that drinking coffee while cortisol levels are high can produce a tolerance to caffeine. Miller also later adds in that article, “One of the key principles of pharmacology is to use a drug when it is needed. Otherwise, we can develop tolerance to a drug administered at the same dose” (“Best time to drink coffee isn’t first thing in the morning: researcher,” 11.7.2013). As a regular coffee drinker, this may explain why when I am looking to pull an all-nighter, I need at least three espresso shots in my coffee to feel any effect.

However, when examining Miller’s findings in depth, there may be flaws present in his conclusions. To determine that the time between 9:30 and 11:30 a.m. is the most effect time to drink coffee, Miller used concepts of chronopharmacology, or the study of the biological rhythms within our body. This biological clock is an internal 24-hour clock, similar to our circadian rhythm. This clock is important because it controls one’s alertness throughout the day. (The Frisky, “Science figured out the best times of day to drink coffee,” 11.13.2013)

What Miller fails to fully acknowledge, as pointed out by other neuroscientists, is that not everyone is on the same internal clock and therefore not on the same cortisol cycle. Lizette Borreli, a writer for Medical Daily, points this out in a recent article, saying, “Early birds will commonly experience a drop of cortisol levels earlier than those who sleep in.” For example, a late-night worker’s cortisol levels and biological clock are probably very different from, say, someone who works the normal 9 a.m. to 5 p.m. shift. Essentially, Miller’s findings are not to be discredited by any means, but should be taken with a grain of salt. It is best to consume caffeine during the times that natural cortisol levels drop is not in question, but rather when those times are for each of us. (“What’s the best time to drink coffee?” 11.08.13)

Great—so you should drink coffee when your cortisol levels are low; but when exactly is that? Honestly, you probably won’t be able to tell on your own without a doctor running tests on you. I am guessing this is why Miller gave what I would call a “best guess” on the times when cortisol levels may be low.

So what should you do? How will you know when it is the right time to consume your coffee? I drink coffee every day. It is very rare if I show up to my 9 a.m. classes without a to-go cup in hand. Even though Miller’s results may not be perfect, he does have evidence to back up his findings. When I drink coffee, I feel more alert, probably because my cortisol is low. According to Miller, if I had peak cortisol levels at the time of my coffee consumption, I would not feel more alert or focused. While the timing of my coffee consumption may be off by 15 minutes or so from that “best time to drink coffee,” maybe my internal clock is just a tad bit off from others.

So the best advice I can give is to pay attention when you drink coffee and see if it actually makes a difference in your alertness. If not, maybe try consuming coffee at a different time. I would suggest trying Miller’s ideal times first and slowly expanding from there. Either way, enjoy your caffeinated experience!


—Delaney Fischer ’15 is a neuroscience major.

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