A 2021 meta-analysis concluded that studies continue to show mixed results regarding the effects of caffeine on mood, and suggested that if caffeine does have an effect on mood, the most significant changes might be a brief alteration in mood states (i.e., anxiety) which are short-lived5.
Extensive research suggested that caffeine intake has been associated with a range of reversible physiological effects, at both lower and higher levels of consumption, suggesting that caffeine intake has no significant or lasting effect on physiological health5,6.
Caffeine and effect on depression
Research suggests that caffeine may help to relieve depressive symptoms or help to protect against depression.
- A 2023 meta-analysis identified an inverse association between the intake of coffee and depressive symptoms, suggesting a 4% reduction in the risk of depression associated with an increase in coffee intake of 240ml per day 16.
- A 2018 large European Study (Sun Cohort) suggested that participants who drank at least 4 cups of coffee per day showed a significantly lower risk of depression than participants who drank less than 1 cup of coffee per day. However, the researchers did not observe an inverse linear dose–response association between coffee consumption and the incidence of depression17.
- A 2016 meta-analysis, accounting for a total of 346,913 individuals and 8,146 cases of depression, suggested that coffee consumption may have a protective effect. A dose-response analysis suggests a J-shaped curve, with the effect reported for up to approximately 300mg caffeine (approximately 4 cups of coffee) per day18.
Caffeine and emotion
Caffeine reliably increases arousal1, but it is currently unclear if and how it influences other dimensions of emotion, such as positive versus negative feelings.
One study evaluated emotional responses to coffee beverages to develop a lexicon to describe the feelings that occur whilst coffee drinking. The results suggested that coffee drinkers sought different emotional experiences from their drink: some preferred coffee to elicit positive-lower energy feelings, some liked to be aroused by the positive-high energy emotions, whilst others desired feelings of a focused mental state19.
Research has suggested that caffeine may accentuate non-habitual caffeine consumers’ emotional responses to negative situations, but not how they choose to regulate such responses20. Further research has considered the impact of caffeine consumption in situations where emotions were already stimulated by watching negative film clips, concluding that caffeine consumption may produce increases in self-reported measures of tension, anxiety, and anger. This effect was altered when coffee was consumed with theanine, which decreased this effect of caffeine21.
