14.11.14

The power of a mid afternoon cup of coffee

As you might have noticed, I spend a lot of time experimenting with different aspects of my diet and lifestyle. I like to look at the impact of things like the number of calories I consume, the balance of macro-nutrients, the amount of sleep I get, the differences between getting up early versus later, and so on.

Obviously, these aren't rigorous scientific studies. I can't double-blind test the results. My sample size of one is not statistically significant. But I enjoy playing with them and, ultimately, personal performance is just that: personal. So, finding what works well for me is valuable.


One of the goals I've been working towards is the best way to get optimal energy levels throughout a working day. I often find that by mid-afternoon on a busy day I'm really starting to slump. I start to lose focus and drift into procrastination.
There is likely a whole set of reasons for this. It's not likely to be down to just one root cause. If I was to guess at one of the primary causes, I'd suspect that it relates to the draining of willpower reserves during the day[1]. My job is quite difficult and requires a lot of decision making, creative thinking, and I also have to work on tasks that I find aversive. Staying on top of all of this requires willpower, which is a limited resource.

Taking my cue from the ideas associated with willpower depletion, I've been experimenting with meal frequency. I've been working on a meal pattern of breakfast, mid-morning snack, lunch, mid-afternoon snack, dinner and supper (occasionally - usually depending on how much exercise I've been doing).  I typically exercise at lunchtime and have lunch immediately after training. If I exercise in the evening, I normally do so before dinner.
I think this has had some success. Although I have noted that typically if I'm working on something particularly aversive or boring I find myself feeling more hungry.

Recently, I've found that I still get an afternoon slump. So, I've started experimenting with increased caffeine intake at around 1500. I pick 1500 as the key time, because I try to avoid consuming caffeine much after 1500. This gives a good amount of time to let any caffeine exit my system before I go to sleep at night. The half-life of caffeine is somewhere between 3 - 10 hours[2].

Before starting this experiment, my general caffeine-related drinking pattern has been to have a cup of brewed coffee at breakfast, followed by a couple of cups of green tea in the morning before lunch and then on in the afternoon after lunch or at around 1500. Taking an extra cup of coffee in the afternoon at about 1500 is a way to significantly increase my caffeine intake. The typical caffeine content of green tea is around 35 mg per cup [3]. The typical caffeine content of a similar sized cup of brewed coffee is 163 mg[4]. This is quite a significant difference.

Although I've only been following this pattern for around a week, I have definitely noticed a difference in alertness and ability to focus after my mid-afternoon coffee. This gets me through to the end of the working day in pretty good shape.
I have noticed a slight impact on my readiness for sleep in the evenings, but this is tolerable.

All of which has made withdrawing from caffeine of all forms very interesting this week. The other caffeine-related hack I'm experimenting with is to take a one week purge from caffeine, once a month, to limit any build-up of caffeine tolerance. I also abstain from caffeine for a week before a major distance running race (i.e. half-marathon or longer), so that I can maximise the benefit of caffeine as an ergogenic aid for endurance performance. There are absolutely loads of studies and references that support the performance benefits of caffeine. This is a good starting point[5] and see references [6] and [7]. Although it should be noted that there are fewer that clearly show abstaining from caffeine beforehand makes a big difference.

References:

[1] Baumeister, R. F., Vohs, K. D., & Tice, D. M. (2007). The Strength Model of Self Control. Current Directions in Pyschological Science, 16, 351-355. doi: 10.1111/j.1467-8721.2007.00534.x
[2] Blanchard, J. & Sawers, S. J. A. (1983). The absolute bioavailability of caffeine in man. European Journal of Clinical Pharmacology, 24, 93-98.
[3] http://www.caffeineinformer.com/caffeine-content/green-tea [retrieved on 06/11/2014]
[4] http://www.caffeineinformer.com/caffeine-content/coffee-brewed [retrieved on 06/11/2014]
[5] http://www.runningwritings.com/2011/08/caffeine-and-running-effectiveness.html [retrieved on 06/11/2014]
[6] Bell, D. G. & McLellan, T. M. (2002). Exercise endurance 1, 3 and 6 h after caffeine ingestion in caffeine users and nonusers. Journal of Applied Physiology, 93. 1227-1234. doi: 10.1152/japplphysiol.00187.2002
[7] Cox, G. R., Desbrow, B., Montgomery, P. G., Anderson, M. E., Bruce, C. R., Macrides, T. A., Martin, D. T., Moquin, A., Roberts, A., Hawley, J. A. & Burke, L. M. (2002). Effect of different protocols of caffeine intake on metabolism and endurance performance. Journal of Applied Physiology, 93. 990-999. doi: 10.1152/japplphysiol.00249.2002

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