Science behind SMART caffeine consumption - how to get the most out of your caffeine, scientifically explained

First, I'll provide a detailed explanation of how coffee modulates your drowsiness, and its positive and negative effects. In the second half, I'll provide tips on strategic caffeine consumption that will help you create an energy reservoir that you could tap into as desired.

Part 1: Science of how caffeine works + positives and negatives 

Here's how the brain modulates drowsiness. Adenosine molecules can either 1) float around in your brain, or 2) bind to receptors. The more adenosine molecules that are bound, the more tired you feel. Adenosine builds up in your body the more you consume ATP throughout the day (ATP consumption allows you to use energy stored in your body). That's why you get more tired as your day progresses. At one point, the adenosine buildup is so great that you fall asleep. Caffeine competes with adenosine for its receptor - if successful, caffeine binds to adenosine receptors instead. This decreases the amount of bound adenosine molecules, which decreases how drowsy you feel.  

Please enjoy my sophisticated illustration of caffeine competing with adenosine in your brain

Caffeine does way more good than bad - a myriad of positive effects have been researched, including  decreased risk of Parkinson’s, Alzheimer’s, and GI cancers. Caffeine is an ingredient in many medicines, including analgesics, muscle medication, migraine relief, and more. It's also a common ingredient in skincare products.These are just a few of many examples - so don't feel guilty if you're a coffee lover! However, there are ways to be smarter about your caffeine indulgence. 

One cup of coffee contains around 70-140 mg of caffeine. Researchers with the Mayo Clinic found that, on average, a person could drink 300-400 mg (about 4 to 5 cups) of coffee a day without adverse effects. The FDA also recommends this amount. Exceeding this can make you agitated and restless, since caffeine stimulates the release of the fight or flight hormone called adrenaline. If you're prone to being anxious or stressed, I would seriously recommend staying under 4-5 cups a day. According to doctors, those with irregular heart conditions should also stay under this number as coffee can increase your heart rate and contribute to arrhythmia. To give you an idea of how difficult it is to actually overdose on coffee: you need to consume 10 g for coffee to be lethal, which equals to roughly 100 cups in quick succession. Other studies suggest that the lethal dose of caffeine is around 100-150 mg per kg of your body. That still ensures you need to drink around 70-100 cups at once for coffee to actually be lethal.  

Scientific studies on caffeine and sleep 

A number of studies have found that caffeine increases sleep latency and reduces sleep duration. A 2017 study by Statistics Canada identified caffeine consumption as one of the leading causes of insufficient and disrupted sleep among Canadians. One study showed that caffeine can trigger repeated nighttime "arousals," during which an individual wakes up briefly, often without being fully conscious. These arousals fragment sleep, which reduces the amount of time spent in deep sleep. This means that even if total sleep time remains unchanged, the quality of sleep may suffer, resulting in grogginess and slower reaction times the following day. According to another study, participants' brain patterns were characteristic of light sleep up to 16 hours after ingesting a double espresso, even though caffeine detectable in their saliva had fallen to zero by the time they went to bed. 

Part 2: How to use all that science to get the most productivity out of your caffeine 

1. Only use caffeine occasionally to avoid developing tolerance - this will ensure your sleep is not impaired. 

Oftentimes, we reach for coffee because we love the flavour or because it gives us a psychological kick (guilty of both, here). Try decaf a few times - you may get a placebo effect. I've tried this and didn't notice a big difference between original and decaf coffee, and so I reach for the caffeinated version when I really need it now instead of as a habitual option after waking up. 

2. For habitual consumers - cycle caffeine 

Cycling refers to either a) a brief period of stopping caffeine consumption, or b) decrease caffeine consumption gradually over time, both in order to reduce tolerance. And when you start using caffeine again, don't go back to the same levels you used to consume prior to cycling - start small. This will decrease withdrawal symptoms such as increased anxiety, restlessness, and headaches. 

3. Cut caffeine around 4pm - 6pm 

This is very important to ensure caffeine doesn't impinge on your sleep. Even if you manage to fall asleep with caffeine in your system, it can cause you to spend significantly longer time in the lighter stages, causing you to feel groggy the next day. We've all had days where we seemed to sleep a decent amount of time, but felt tired the next day. To avoid this, cut coffee around 4 pm - 6 pm. This is because the half life of caffeine is around 5-6 hours, which means half of the amount you consumed remains 5-6 hours after you consume it. This way, the stimulation will wear off by the time you go to bed. You don't want to fall into the dangerous but very common loop of not being able to sleep well because of excess caffeine, waking up and not feeling rested, and reaching for caffeine again, only to continue the cycle. 

4. Have some before your workout

I was able to find lots of scientific studies that found caffeine can help you last longer in your workout. Some studies even found that caffeine can improve athletic performance. Many studies found that caffeine improves performance in cycling, running, and even driving, but it doesn't show as consistent of a pattern when it comes to muscle training.

5. If you're having caffeine to study for a test or meet a work deadline 

If you're going to need lots of stimulation that day, space out your caffeine. You know the half life is around 5-6 hours, and it takes around 2 hours after ingestion for the full effects of caffeine to manifest. Thus, have your next cup around 3-4 hours later, and so on. Drinking too much coffee at once can lead to a big crash later, which you don't want if you need to go hard that day. Not to mention, you only have a limited number of adenosine receptors in your brain anyway, so at one point, caffeine ceases to make such a difference (this will make even more sense when you read #6) - so don't drink too much at once! Practice spaced repetition!

5.5. Avoid excess sugar if you're consuming lots of caffeine that day

Lots of sugar = sugar crash, and lots of caffeine = caffeine crash. You don't want to crash to the power of 2. I recommend staying away from energy drinks if you're looking to study or work the whole day. Energy drinks or other super sugary drinks are better for when you need a quick surge of energy in the next couple of hours, but don't mind crashing around 4-6 hours later. This is not amenable to, say, exam periods. 

6. Don't consume caffeine during your regular cortisol surges

Here's some super fancy science advice for those who are not screwing around when it comes to their coffee. Cortisol is otherwise known as the stress hormone. If you can, avoid caffeine around your average cortisol surges, which scientists have found occurs between 9 am, 12 pm-1 pm, and 5:30-6:30 pm. This is because consuming caffeine during these cortisol surges, according to researchers, diminishes its effects. It is a generally accepted fact among the scientific community that 1) caffeine doesn't do much for your body when cortisol levels are high, and 2) most people's cortisol levels are highest between 8-9 am. Making it a habit to consume caffeine during these cortisol surges can contribute to building tolerance, or drinking excessively to get your buzz, so you're getting all the negatives with none of the positives. By the way, these cortisol surges are regulated by sunlight, which means whatever your individual sleep schedule may be, it's not going to alter the cortisol surges our bodies have been undergoing for millions of years  through evolution.  

7. Eliminate coffee jitters (nervousness, restlessness, anxiety) 

Coffee may actually be making you MORE stressed for the very thing you're taking it for! I realized the very hard way that excess coffee was actually making me even more fearful of the tests I was taking it to study for. To eliminate coffee jitters, ensure you're drinking enough water (up to one glass for every cup of coffee) as this flushes excess caffeine out of your system. Some recommend ingesting water-soluble minerals such as vitamin C and D as these can also be flushed out when you drink water, though I haven't found scientific evidence to suggest this actually helps with jitters. In order to avoid jitters in the first place, try the tips 1-6.

And that's it. If you're gonna have coffee anyway, especially if it's to improve your performance on any task, might as well make sure you're getting the most out of it as possible, right? 

Sincerely, 

Annesa 

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Here are some scientific articles for further reading on the topics I've discussed above. 

Bidel, S., & Tuomilehto, J. (2013). The Emerging Health Benefits of Coffee with an Emphasis on Type 2 Diabetes and Cardiovascular Disease. European endocrinology, 9(2), 99–106. https://doi.org/10.17925/EE.2013.09.02.99

Irish, LA, Mead, MP, Cao, L, Veronda, AC, Crosby, RD. The effect of caffeine abstinence on sleep among habitual caffeine users with poor sleep. J Sleep Res. 2020; 00:e13048. https://doi.org/10.1111/jsr.13048

Kerpershoek, M. L., Antypa, N., & Van den Berg, J. F. (2018). Evening use of caffeine moderates the relationship between caffeine consumption and subjective sleep quality in students. Journal of sleep research, 27(5), e12670. https://doi.org/10.1111/jsr.12670

Lieberman, H. R., Tharion, W. J., Shukitt-Hale, B., Speckman, K. L., & Tulley, R. (2002). Effects of caffeine, sleep loss, and stress on cognitive performance and mood during U.S. Navy SEAL training. Psychopharmacology, 164(3), 250–261. https://doi.org/10.1007/s00213-002-1217-9

Irwin, C., Desbrow, B., Ellis, A., O'Keeffe, B., Grant, G., & Leveritt, M. (2011). Caffeine withdrawal and high-intensity endurance cycling performance. Journal of sports sciences, 29(5), 509–515. https://doi.org/10.1080/02640414.2010.541480

Yoto A, Motoki M, Murao S, Yokogoshi H. Effects of L-theanine or caffeine intake on changes in blood pressure under physical and psychological stresses. J Physiol Anthropol. 2012;31(1):28. Published 2012 Oct 29. https://doi.org/10.1186/1880-6805-31-28

Mielgo-Ayuso, J., Marques-Jiménez, D., Refoyo, I., Del Coso, J., León-Guereño, P., & Calleja-González, J. (2019). Effect of Caffeine Supplementation on Sports Performance Based on Differences Between Sexes: A Systematic Review. Nutrients, 11(10), 2313. https://doi.org/10.3390/nu11102313

Irish, L. A., Mead, M. P., Cao, L., Veronda, A. C., & Crosby, R. D. (2020, May 6). The effect of caffeine abstinence on sleep among habitual caffeine users with poor sleep. Retrieved from https://onlinelibrary.wiley.com/doi/abs/10.1111/jsr.13048