Over 80% of adults consume caffeine (1), but do you know why caffeine works, or how to use it efficiently? If you aim to use caffeine to enhance performance, there’s a good chance that you are consuming more caffeine than you need to. Read on to find out more about how caffeine works, what aspects of cognitive performance are improved, how to stop caffeine interfering with sleep, and how much caffeine is needed to boost performance.
I didn’t become a coffee drinker until I started racing for a French cycling team, back in 2002. Sitting at a café in the town square, before one of my first team training sessions, marked my initiation into the pre-ride coffee ritual. My team-mate gestured to the waiter, ordered “deux cafés”, and a few minutes later, I was staring at a tiny cup of dark, oily liquid. I adjusted the espresso shot to suit my naïve palate with a liberal dose of sugar, downed it, and we hit the road. Despite this inauspicious start, I came to appreciate the nuances in coffee; its provenance, brew methods, and performance-enhancing effects. However, at the time, I didn’t realise that I was probably using more caffeine than I needed to.
Caffeine Is A Powerful Psychoactive Drug
Coffee is one of the world’s most popular caffeine delivery mechanisms, accounting for more than half of the world’s caffeine consumption. For many of us, it’s a very pleasurable way to consume this powerful psychoactive drug. Yes, caffeine is a drug.
Prescription stimulants, such as modafinil, have been getting more press recently. Modafinil has been touted as an illicit ‘study aid’ for students looking for an edge and even as a legitimate means to keep military pilots awake (3). Many people would never consider using modafinil to enhance their performance, but those same people are more than happy to chug away on their coffee throughout the day. While coffee consumption is more socially acceptable than pill-popping, the evidence suggests that the performance-enhancing effects of caffeine are at least as potent as modafinil (2).
Caffeine significantly changes brain function. The effects are primarily the result of caffeine molecules having a similar structure to a molecule called adenosine. During the day, the concentration of adenosine molecules builds up in our brain, as a by-product of our brain cells firing. Adenosine binds to receptors in our brain, and slows the receptor cells down, making us feel sleepy. However, caffeine stops the adenosine binding with the receptors. Also, when caffeine molecules connect with an adenosine receptor, instead of slowing them down, it speeds the cells up and stimulates our nervous system.
The Performance Enhancing Benefits Of Caffeine
Caffeine performance-enhancing effects include improved alertness, vigilance, attention and reaction time, which are great for both sports and work performance. However, most of us are probably consuming more caffeine than we need to.
Regular caffeine intake increases the number of adenosine receptors in our nervous system (4). The increases number of receptors means that we become ‘habituated’ to caffeine – we get used to it. However, even high users of caffeine do not appear to need more caffeine, compared to low users, to maintain the performance benefits (5).
The problem for many caffeine aficionados is that, while high-dose users can still experience performance-enhancing benefits, these benefits also interfere with sleep. Even if you think you are immune to the effects of caffeine, it’s unlikely to be true. Disrupted sleep has probably just become your new normal.
How Caffeine Screws Your Sleep
It takes about 30 minutes for caffeine to reach peak levels in our blood plasma, then we can enjoy its effects for the next 4 to 6 hours. However, this also means that if you drink a ‘grande latte’ with an extra shot at 07:00 am on your morning commute, which contains around 200mg of caffeine, there could still be enough caffeine hanging around, stimulating your nervous system and interfering with sleep, at 11:00 pm.
Even if you stop drinking coffee 6 hours before you go to bed, it could reduce your sleep time by more than 1 hour (6). To compound the issue, consuming caffeine in the hours before you go to bed can delay your circadian rhythm (your body clock). This delay makes it more difficult to go to sleep at the same time the following night. Basically, we are giving ourselves a small dose of jetlag (7).
Which Drinks Contain The Most Caffeine?
Another common misconception is that milky coffees contain less caffeine than an espresso. However, the amount of caffeine in a drink varies significantly, based on both volume and brewing method. Fortunately, in 2019, a group of committed researchers set out to demystify these differences (8). The researchers investigated the effects of eight different brewing methods: three types of Espresso, Moka and the French Press method were included. For the first time in the scientific literature, the extraction characteristics of Cold Brew, V60, and Aeropress were also included. Coffee geeks rejoice.
The espresso brewing method is a very efficient means to extract caffeine from ground coffee. However, the low-volume of the drink means that we don’t consume very much caffeine, relative to other coffee drinks. For example, milk-based beverages such as lattes can contain much more caffeine than espresso, even though the concentration of caffeine is lower because we generally use much larger cups for these drinks.
What Is The Minimum Effective Dose?
The ability of caffeine to enhance performance is dose-dependent and can be influenced by body mass. I could boost my cognitive performance with a dose as low as 0.3mg/kg/hour (9). I weigh 73kg, which means a dose around 22 mg; equivalent to an espresso cup filled with French press coffee, is enough.
A helpful review, published in 2016, summarised the effects of caffeine on cognitive, physical and occupational performance (1).
Doses of approximately 0.5–4.0 mg kg−1 (∼40–300 mg) can improve cognitive function in rested individuals.
Doses of 3–7 mg kg−1 (∼200–500 mg) ingested approximately 1 h before exercise can enhance physical performance in a wide range of exercise types.
The message is simple. If you love coffee, consume it little and often. If you want to drink more, choose a brew method that results in lower caffeine, and stop as early as possible. What’s your preferred coffee type and schedule? Let me know in the comments.
References
1. McLellan, T. M., Caldwell, J. A., & Lieberman, H. R. (2016). A review of caffeine’s effects on cognitive, physical and occupational performance. Neuroscience and Biobehavioral Reviews, 71, 294–312. https://doi.org/10.1016/j.neubiorev.2016.09.001
2. Wesensten, N., Belenky, G., Kautz, M.A., Thorne, D.R., Reichardt, R.M., Balkin, T.J. (2002) Maintaining alertness and performance during sleep deprivation: modafinil versus caffeine. Psychopharmacology. 159 (3) p. 238-247
3. Ooi, Timotheus & Wong, Sheau & See, Brian. (2019). Modafinil as a Stimulant for Military Aviators. Aerospace Medicine and Human Performance. 90. 480-483. 10.3357/AMHP.5298.2019.
4. O’callaghan, F., Muurlink, O., & Reid, N. (2018). Effects of caffeine on sleep quality and daytime functioning. Risk Management and Healthcare Policy, 11, 263–271. https://doi.org/10.2147/RMHP.S156404
5. Dark, H.E., Kamimori, G.H., LaValle, C.R. & Eonta, S.E. (2015) Effects of High Habitual Caffeine Use on Performance During One Night of Sleep Deprivation: Do High Users Need Larger Doses to Maintain Vigilance? Journal of Caffeine Research. 5(4)
6. Christopher, D., Timothy, R., John, S., & Thomas, R. (2013). Caffeine Effects on Sleep Taken 0, 3, or 6 Hours before Going to Bed. Journal of Clinical Sleep Medicine, 9(11), 1195–1200. https://doi.org/10.5664/jcsm.3170
7. Burke, T. M., Markwald, R. R., McHill, A. W., Chinoy, E. D., Snider, J. A., Bessman, S. C., … Wright, K. P. (2015). Effects of caffeine on the human circadian clock in vivo and in vitro. Science Translational Medicine, 7(305). https://doi.org/10.1126/scitranslmed.aac5125
8. Angeloni, G., Guerrini, L., Masella, P., Bellumori, M., Daluiso, S., Parenti, A., & Innocenti, M. (2019). What kind of coffee do you drink? An investigation on effects of eight different extraction methods. Food Research International, 116(June 2018), 1327–1335. https://doi.org/10.1016/j.foodres.2018.10.022\
9. Wyatt, J. K., Cajochen, C., Ritz-De Cecco, A., Czeisler, C. A., & Dijk, D. J. (2004). Low-dose repeated caffeine administration for circadian-phase-dependent performance degradation during extended wakefulness. Sleep, 27(3), 374–381. https://doi.org/10.1093/sleep/27.3.374
