Motivation and emotion/Book/2013/Caffeine and emotion

Caffeine and emotion:
What is the effect of caffeine on emotion?

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Overview

This chapter aims to provide information and research that is relevant to the interaction between caffeine and emotion in a way that is easy to read and understand in the hope that this information will assist the reader to improve their life, as consistent with the theme of the wider text Motivation and Emotion: Improve Your Life (2013) within which this chapter is situated. It is important to note that the research on this topic is not perfect and there are studies in which results vary from the broader body of the literature, these studies will be reported where relevant but for the most part literature for which results have been recreated or fit within the main body of the research will be reported. The chapter will begin by providing a list of key terms and their definitions, as well as a list of caffeinated beverages and the approximate amounts of caffeine they contain, this will be followed by outlining the effects of caffeine on emotion, including but not limited to, the effects of caffeine on anxiety. The chapter will then go on to make suggestions as to how the effects of caffeine on emotion may be regulated. Finally this chapter will conclude that based upon the literature presented in this chapter it is advisable to limit caffeine intake as it is linked to greater levels of stress, anxiety, tension and depression. Further advice offered based upon the research proposed in this chapter is that it is advisable to limit caffeine consumption to avoid withdrawal effects and keep caffeine levels up during important tasks, if you have consumed caffeine, to avoid negative affect associated with withdrawal. The differences and possible benefits of tea to some other caffeinated beverages are also explained. While research shows that some beverages and situations do not report the same negative emotional outcomes of caffeine consumption it is wise to consider when and how much caffeine you are consuming and how regularly in relation to maintaining positive affect throughout all aspects of your life.

Key terms and definitions

Key terms used throughout this chapter will be defined in this section, as they are defined on Dictionary.com (http://dictionary.reference.com/) as appropriate for their context within this chapter.

Anxiety - A state of mental tension and, or apprehension occurring in some forms of mental disorder. See Also Anxiety
Affect - (In the context of this chapter 'affect', when used as a noun, will be considered synonymous with mood) an emotion or feeling, may be an observable indicator of mental illness.
Caffeine - A drug, commonly consumed in food and beverages including tea and coffee, used in medicine as a stimulant for the nervous system.
Depression - (In the context of this chapter 'depression' and 'clinical depression' will be considered synonymous) A state of emotion characterised by behavioral withdrawal and unhappiness, more intense and or prolonged than considered usual, often without obvious cause. See also Motivation and emotion/Textbook/Motivation/Depression/Depression assessment tools
Withdrawal - Cessation of using an addictive drug, often characterised by side effects, as distinct from behavioral withdrawal. See also Addiction

Beverages - Approximate Caffeine Content

Caffeine content of commonly consumed beverages as reported by Veleber & Templer (1984).

Cup of Brewed Coffee – 125mg 
Cup of Instant Coffee – 92.5mg
Cup of Tea – 67.5mg
Can of Soft Drink – 50mg
Cup of Decaffeinated Coffee – 3mg
Cup of Herbal Tea – 0mg

Caffeine and Emotion: The Literature

There are two major effects observed in the literature of caffeine on emotion; the first is the impact caffeine has on anxiety, and the second is caffeine's ability to improve the moods of some consumers, these two effects of caffeine on emotion will be elaborated in the sections to follow and a third section will outline some other relevant points of the literature relating to the effects of caffeine on emotion.

Caffeine and Anxiety

Literature on the topic of caffeine and emotion is generally in agreement that caffeine causes increased levels of anxiety symptoms in the post test anxiety measures (Veleber & Templer, 1984; Rogers, Heatherly, Mullings, Wu & Leonards, 2006). The relationship between anxiety and caffeine is often attributed to the physiological effects to which caffeine contributes including headache, tremulousness, reflex hyper-excitability and muscular twitches (Veleber & Templer, 1984). One study (Rogers et al., 2006) found that state anxiety in non-consumers of caffeine was affected by caffeine consumption and that both regular caffeine consumers and non-consumers reacted more quickly to social threat words following the consumption of caffeine. Some literature does not refer directly to anxiety as the emotional state with which caffeine interacts, as in Smit and Rogers (2000), such notable symptoms as jitteriness, energetic arousal and tense arousal are still highlighted however and relevant to the literature on the subject.

Caffeine's Ability to Improve the Moods of Some

Many studies observe positive effects of caffeine on mood (James & Rogers, 2005), however there seems to be a very specific combination of variables leading to this effect. Caffeine consumption improves the mood of regular caffeine consumers, they encounter feelings of well being and increased alertness, however if regular caffeine consumers cease to consume caffeine suddenly, mood is negatively affected and they may feel dissatisfied, anxious or restless (Goldstein & Wallace, 1997). There is debate over the possible causes of this negative effect on the moods of regular caffeine consumers with the most widely agreed reason being that caffeine withdrawals cause the negative emotion and associated positive mood change when caffeine consumption is resumed (James & Rogers, 2005). Goldstein and Wallace (1997) whilst acknowledging the signs of withdrawal and withdrawal reversal suggest there could be alternative reasons for these changes in affects; individuals who (without the effects of a stimulant) maintain a lower level of mood and or arousal, may be more prone to becoming regular caffeine consumers and the negative mood change associated with a sudden lack of caffeine may simply be those individuals returning to their non caffeine affected state. Goldstein & wallace (1997) assert that the only way to conclusively identify whether the observed effects are related to withdrawal is to conduct a long term study. One long term study described by James and Rogers (2005) supports the evidence of withdrawal and withdrawal reversal in an experiment designed to observe the effects of tolerance and withdrawal. James and Rogers (2005) conclude that this study showed no positive effects of caffeine on mood once withdrawal effects were accounted for.

Caffeine and Emotion; Broadly

The literature also highlights the effects of caffeine on post caffeine consumption depression measures (Veleber & Templer, 1984). Stress is also an emotional factor recognised to be influenced by caffeine (Mason, 2012). An interesting finding by a study assessing whether perceived mood regulation ability can predict regulation of mood whilst engaging in a task (Hovanitz, Hursh & Hudepohl, 2011), noted that having consumed caffeine prior to the experimental phase of the study saw an increase in reported ability to regulate affect. Participants who reported low levels of ability to regulate mood were less able to correct declining positive affect than those who reported high ability, this suggests a possible relationship between caffeine and ability to inhibit decreasing positive affect (Hovanitz et al., 2011). Hovanitz et al. (2011) define positive affect as; distinctive dimensions in which a person feels enthusiastic, active and alert. Another interesting effect of caffeine in the study by Smit and Rogers (2000), was an increase in boredom beginning at about one hour after the dose of caffeine was consumed.

An Exception

A study by Sünram-Lea, Owen-Lynch, Robinson, Jones, and Hu (2012) into levels of stress and anxiety in a firefighting training exercise found that an energy drink containing glucose and caffeine reduced self reported stress following the exercise. The researchers in the aforementioned study suggested that when stress is combined with a physically demanding task an energy drink containing caffeine may assist to reduce stress levels.

Who is Affected by Caffeine and to What Extent?

The effects of caffeine vary between individuals, this section will discuss the differences in effects observed between several groups which reoccur throughout the literature. In adults the most commonly assessed difference in effects of caffeine are those defined by levels of caffeine consumption, that is to say the effects of caffeine consumption on emotion differ between those who do not consume caffeine regularly, those who consume only a moderate amount and those who consume a high amount. It is interesting to note the debate in the literature as to how the groups, moderate and high consumers, form in the population, there is some suggestion that those who are less negatively affected or more positively affected in terms of mood and cognitive performance tend to consume higher levels of caffeine (Attwood, Higgs & Terry, 2007). An alternative to this view is that those individuals who drink beverages lower in caffeine per beverage such as decaffeinated coffee consume greater amounts of caffeine (Veleber & Templer, 1984). The other focus group assessed in relation the the effects of caffeine on emotion is children. Each of the groups outlined and the extent to which they are affected by caffeine will be elaborated on below.

As more that 80% of the population consumes at least one caffeinated beverage daily, individuals who do not consume caffeine are very rare, this along with the possibility of underlying reasons for the non consumption of caffeine makes them difficult to generalise to the broader public and as a result there is little research into the effects of caffeine on such individuals (James & Rogers, 2005).

Research has also been carried out to investigate whether caffeine's effects on mood and other factors could be predicted by personality traits such as extroversion however this was found to be statistically non significant (Liguori, Grass & Hughes, 1999).

Regular Caffeine Consumers - Both Moderate and High Level

Results vary slightly in the literature pertaining to regular caffeine consumers however there are observable trends in results which have been recreated and studied repeatedly and as such these results will be reported. A study by Attwood, Higgs and Terry (2007) found that even small amounts of caffeine, levels likely to be found in one caffeine containing beverage, can affect the mood of regular caffeine consumers, even when they were tolerant to the thirst inducing effect. It is important to note that when dividing caffeine consumers into groups studies rarely concern themselves with the way in which people consume their caffeine, some beverages for example appear to have different effects to others due to substances other than caffeine present and thus relevant to the question of the effects of caffeine on emotion.

Children and Caffeine on Emotion

A study by Heatherley et al. (2006) investigated the affects of caffeine on 9-10 year old children, finding that, just as in adults (James & Rogers, 2005), the cognitive ability and mood of regular caffeine consumers improved after consuming caffeine, the researchers propose however that this should not be interpreted as caffeine having positive effects as this result may also be explained by the withdrawal reversal effect, that is; regular caffeine consumers abstain from the consumption of alcohol for a period before testing, and show cognitive performance and moods less favourable than those observed in the non-consumption group, following caffeine consumption these habitual caffeine consumers improve in cognitive performance and affect, however not exceeding the levels of the non-consumer group, leading researchers to believe that these effects may be the result of withdrawal reversal. A similar study by Goldstein and Wallace (1997) produced similar results, though posed the question that children may have some differences in reactions to caffeine as indicated by children's lack of complaints of headache, a common caffeine withdrawal symptom in adults, and relatively high complaints of muscular pain which is comparatively rare in adults. Regular caffeine consumers are often tolerant to the thirst provoking effect of caffeine however they are still susceptible to its affects on mood (Smit & Rogers, 2000).

Regulating the Effects of Caffeine on Emotion

While the message obtained from the literature about caffeine and emotion is that it is unlikely to have any positive effects, caffeine consumption is widely accepted and often culturally expected, James and Rogers (2005) note that caffeine non consumption is rare if not non existent in contemporary western culture with more than 80% of people consuming one or more caffeinated beverages daily. There are options to reduce your caffeine intake however such as decaffeinated coffee, tea and soft drinks, these beverages do still contain some caffeine. The approximate caffeine content of commonly consumed beverages is listed above at Beverages - Approximate Caffeine Content. Based upon the literature presented in this chapter it is advisable to limit caffeine intake as it is linked to greater levels of stress (Mason, 2012), anxiety (Veleber & Templer, 1984; Rogers et al., 2006; Heatherley et al., 2006), tension and depression (Veleber & Templer, 1984).

Energy Drinks

It is possible that in the right circumstances, such as when physical exertion is necessary, a caffeinated energy drink may assist to reduce stress (Sünram-Lea et al., 2012) however there are other possible contributors to this outcome which have not been ruled out such as the widely accepted mood improving effects of physical activity.

Tea

It is widely known that coffee contains caffeine, and the emotional effects explained throughout this chapter are often attributed to drinking coffee however tea, which contains comparable levels of caffeine, has a very different reputation. Tea is often considered relaxing (Rogers, Smith, Heatherley & Pleydell-Pearce, 2008), while coffee is considered stimulating. A measure of jitteriness found that Caffeine and a placebo scored highest followed by caffeine and theanine together, theanine alone and a double placebo respectively (Rogers et al., 2008). Significant levels were recorded of responses to measures of an anxiety scale for items 'pounding heart', 'hands trembling', 'feeling hot' and 'alert' in the caffeine and placebo group while the only significant response for the caffeine and theanine condition was 'alert' (Rogers et al., 2008). These findings suggest that; if you feel that you require a stimulant in order to perform better cognitively however you are concerned about maintaining your emotional state tea is going to be more effective than coffee. Consuming the substances present in tea still increases jitteriness when compared with a double placebo however it is to a reduced extent.

Avoiding Caffeine Tolerance and Withdrawal

As the literature has shown there are considerable tolerance and withdrawal effects of caffeine, the good news is that these effects are not as long term as one might fear. Caffeine has a half life, in adults, of about six hours meaning that if someone does not consume caffeine over night levels of caffeine in the body are significantly reduced by the morning (James & Rogers, 2005). Tolerance to caffeine in adults has been found to peak at three to five days of continuous use (James & Rogers, 2005), after which point negative affects of caffeine such as increased anxiety become less frequent. Caffeine withdrawals occur when a caffeine consumption stops suddenly however these symptoms stop after three to five days and not exceeding one week(James & Rogers, 2005). What this means, in a practical, real life context is that though negative affect is associated with stopping your consumption of caffeine this effect is not long lasting and may be as short as three days and no longer than seven days. Drastically reducing your caffeine intake is likely to save you money and will also mean that you don't feel so sluggish without your caffeine hit, and the best part is it should only take a week for you not to feel like you need it anymore! Alternatively, if you are considering increasing your level of caffeine intake, in order to rely on the tolerance effect of high and regular caffeine consumption you should be warned that this is one area on which the research is not unanimous, Attwood et al. (2007) report that small doses of caffeine affect mood levels even when the consumer is tolerant to other effects of caffeine such as thirst promotion. Based upon the research proposed in this chapter it is advisable to limit caffeine consumption to avoid withdrawal effects and keep caffeine levels up during important tasks, if you have consumed caffeine, to avoid negative affect associated with withdrawal.

Conclusion

This chapter has aimed to provide information and research that is relevant to the interaction between caffeine and in the hope that this information will assist the reader to improve their life, as consistent with the theme of the wider text Motivation and Emotion: Improve Your Life (2013) . It is important to note that the research on this topic is not perfect and there are studies in which results vary from the broader body of the literature, these studies have been conveyed where relevant. In conclusion this chapter has reported the major findings of the literature in relation to two major effects observed in the literature of caffeine on emotion; the first being the impact of caffeine on anxiety, and the second; caffeine's ability to improve the moods of some consumers, concluding that; based upon the literature presented in this chapter it is advisable to limit caffeine intake as it is linked to greater levels of stress, anxiety, tension and depression. Further advice offered based upon the research proposed in this chapter is that it is advisable to limit caffeine consumption to avoid withdrawal effects and keep caffeine levels up during important tasks, if you have consumed caffeine, to avoid negative affect associated with withdrawal. Another option to consider in the event where you feel a stimulant would be advantageous is drinking tea instead of coffee or a caffeinated soft drink, this is because tea contains theanine which counteracts the effects of caffeine to an extent and reduces most of the anxiety indicators usually associated with caffeine consumption. While drinking tea is not the perfect solution, it may be less detrimental than consuming other caffeinated beverages. While research shows that some beverages and situations do not report the same negative emotional outcomes of caffeine consumption it is wise to consider when and how much caffeine you are consuming and how regularly in relation to maintaining positive affect throughout all aspects of your life. It is hoped that this information, along with the definitions of key terms and information as to the caffeine content of commonly consumed beverages will assist you in deciding how to tackle caffeine’s contribution to your emotional state.

References

Attwood, A. S., Higgs, S. & Terry, P. (2007). Differential responsiveness to caffeine and perceived effects of caffeine in moderate and high regular caffeine consumers. Psychopharmacology, 190(4), 469-477. doi: 10.1007/s00213-006-0643-5

Goldstein, A. & Wallace, M. E. (1997). Caffeine Dependence in School Children? Experimental and Clinical Psychopharmacology, 5(4), 388-392. doi: 10.1037/1064-1297.5.4.388

Heatherley, S. V., Hancock, K. M. F. & Rogers, P. J. (2006). Psychostimulant and other effects of caffeine in 9- to 11-year-old children. Journal of Child Psychology and Psychiatry, 47(2), 135-142. doi: 10.1111/j.1469-7610.2005.01457.x

Hovanitz, C. A., Hursh, A. N. & Hudepohl, A. D. (2011). Dimensions of Affect Modulated by Perceived Mood Regulation Ability. Applied Psychophysiology & Biofeedback, 36(2), 133-119. doi: 10.1007/s10484-011-9154-1

James, J. E. & Rogers, P. J. (2005). Effects of caffeine on performance and mood: withdrawal reversal is the most plausible explanation. Psychopharmacology, 182(1), 1-8. doi: 10.1007/s00213-005-0084-6

Liguori, A., Grass, J.A. & Hughes, J. R. (1999). Subjective effects of caffeine among introverts and extraverts in the morning and evening. Experimental and Clinical Psychopharmacology, 7(3), 244-249. doi: 10.1037/1064-1297.7.3.244

Mason, A. (2012). How your diet can affect stress levels. Occupational Health, 64(12), 25-25. Retrieved from: http://web.ebscohost.com.ezproxy1.canberra.edu.au/ehost/detail?vid=7&sid=8d06f802-e292-4bd1-a697-fd3bdc8ac388%40sessionmgr10&hid=22&bdata=#db=heh&AN=84367990

Rogers, P.J., Heatherley, S.V., Mullings, E. L., Wu, Y. & Leonards, U. (2006). Caffeine and Anxiety. Appetite, 47(2), 274-274. doi:10.1016/j.appet.2006.07.057

Rogers, P. J., Smith, J. E., Heatherley, S. V. & Pleydell-Pearce, C. W. (2008). Time for tea: mood, blood pressure and cognitive performance effects of caffeine and theanine administered alone and together. Psychopharmacology, 195(4), 569-577. doi: 10.1007/s00213-007-0938-1

Smit, H.J. & Rogers, P.J. (2000). Effects of low doses of caffeine on cognitive performance, mood and thirst in low and higher caffeine consumers. Psychopharmacology, 152(2), 167-173. Retrieved from: http://web.ebscohost.com.ezproxy1.canberra.edu.au/ehost/detail?sid=303022a0-6c5a-48a7-8766-99609c8119e6%40sessionmgr11&vid=1&hid=22&bdata=#db=pbh&AN=4694123

Sünram-Lea, S., Owen-Lynch, J., Robinson, S., Jones, E. & Hu, H. (2012). The Effect of Energy Drinks on Cortisol levels, Cognition and Mood During a Fire-fighting Exercise. Pharmacology, 219(1), 83-97. doi: 10.1007/s00213-011-2379-0

Veleber, D. M. & Templer, D. I. (1984). Effects of caffeine on anxiety and depression. Journal of Abnormal Psychology, 93(1), 120-122. doi:10.1037/0021-843X.93.1.120

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