|This could be your new wake-up routine: Strong coffee and a bath in blue light.|
I guess Essing, whose previous article "When ‘Study Drugs’ Kill" took a reasonably critical stance towards the use of Adderal and similar drugs by healthy individuals, will be delighted by the results C. Martyn Beaven and Johan Ekström present in their latest paper in the peer-reviewed open access journal PLOS|One (Beaven. 2013). The intention of their experiment was ...
"[....] to compare and contrast the physiological responses to blue light and caffeine, administered both separately and conjointly. Measures of cognitive function, reaction time and wakefulness were assessed and it was hypothesized that similarities would be observed with the administration of 240 mg of caffeine and a 1 h dose of ~40 lx blue light." (Beaven. 2013)Moreover, Beaven and Ekström assumed that combining the caffeine equivalent of two small or one large, strong coffees with the 'enlightening' power of a r ~40lx blue light LED light source (Techlight® RGB, 3W, λmax = 470 nm) would induce alerting and psychomotor effects greater than either intervention in isolation.
www.cognitivefun.net, so just try them out and judge for yourself how significant they are).In view of the fact that you will probably have read the "Sunlight à la Carte" (read more) article I published as part of my Circadian Rhythm Series, you shouldn't be surprised by either, ...
- the experimental design that involved the ingestion of a gelatine capsule containing either 240 mg of caffeine or a visually indistinguishable sugar placebo with a small glass of water (CAF), the exposure to ~40 lx of blue light from a LED light source (Techlight® RGB, 3W, λmax = 470 nm) or a white light alternative (~100 lx) for 1 h (BLU) or a combination of both, or
- the assumption that caffeine and blue light should exert additive effects on both physical and psychological measures of alertness
|Figure 1: Eye color determines the extent of the melatonin suppressing effects of 2h of bright light exposure during the night. The effect is significantly stronger in "dark-eyed" Asians vs. "light-eyed" Caucasians (Higuchi. 2007)|
Contrary to what you may have expected, the suppression was increased for the Asians (see Figure 1), not the Caucasians, of whom you'd argue that their ancestors lived at a latitude, where sun is scarce in the winter time, so that you'd have to make the most of it, when it shines.
If we now turn to the results of the study at hand, we'll see that Beaven and Ekström observed a very similar trend in their study, where he increase in visual reactions in the blue light only condition was significantly more pronounced in the blue-eyed, non-shift worker, non-smoking, low to moderate caffeine and alcohol consuming study participants (13 men, 18 women) than in their darker-eyed peers.
Beware of the consequences of the Yerkes-Dodson law
The researchers go on to explain that "[b]oth blue light exposure and caffeine ingestion improved accuracy in the visual Go/No-Go task", but that their combination "did not result in enhancement in the number of correct responses" (see Accuracy in incongruent task in Figure 2). For caffeine alone similar effects have been observed. These observations form the basis of the"Yerkes-Dodson law", in which it is postulated that the relationship between arousal and performance follows an inverted U-shape curve (Fredholm. 1999). Consequently, Beaven & Ekström suspect that
"[...], it is possible to rationalize that the combined treatment of blue light and caffeine dose exceeded the optimal state of arousal and consequently resulted in impaired accuracy." (Beaven. 2013)At first sight, this hypothesis appears to conflict the improved fast reaction time the researchers observed in the visual Go/No Go task, but when you come to think about it, the stimulating effect of caffeine + blue light that is an advantage, when it comes to relatively simple tasks, may well be too pronounced for an exercise that requires a higher degree of mental focus / contentration.
- Beaven, C. M., & Ekström, J. (2013). A comparison of blue light and caffeine effects on cognitive function and alertness in humans. PloS one, 8(10), e76707.
- Essing, T. (2013). Managing The Risks Of Taking Adderall To Enhance Work Performance. Forbes.com. Dec. 06 2013 < http://www.forbes.com/sites/toddessig/2013/12/06/managing-the-risks-of-taking-adderall-to-enhance-work-performance/ > retrieved on 12-24-2013.
- Fredholm, B. B., Bättig, K., Holmén, J., Nehlig, A., & Zvartau, E. E. (1999). Actions of caffeine in the brain with special reference to factors that contribute to its widespread use. Pharmacological reviews, 51(1), 83-133.
- Higuchi, S., Motohashi, Y., Ishibashi, K., & Maeda, T. (2007). Influence of eye colors of Caucasians and Asians on suppression of melatonin secretion by light. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 292(6), R2352-R2356.
- Petrow, S. (2013). The Drugs of Work-Performance Enhancement. The Atlantic. < http://www.theatlantic.com/health/archive/2013/11/the-drugs-of-work-performance-enhancement/281055/ > retrieved on 12-24-2013.