Summary: A large real-world study of 236 young adults found that caffeine reliably increases positive emotions, especially in the morning. Participants who had a cup of coffee or another caffeinated beverage reported feeling happier and more enthusiastic on those mornings compared with similar times on days without caffeine.
The boost in positive mood appeared regardless of participants’ typical caffeine intake, levels of anxiety or depressive symptoms, or reported sleep problems. Researchers attribute the effect to caffeine’s action on adenosine receptors and its downstream influence on brain systems related to alertness and reward; mild overnight withdrawal may also contribute to the morning improvement.
Key Facts:
- Morning impact: The mood-enhancing effect of caffeine is strongest early in the day, within the first two to three hours after waking.
- Consistent across groups: Positive effects were observed regardless of habitual caffeine use, anxiety, depressive symptoms, or sleep quality.
- Proposed mechanism: Caffeine blocks adenosine receptors and can increase dopamine activity in brain regions linked to mood and alertness.
Source: Bielefeld University and the University of Warwick, published in Scientific Reports
Caffeine and morning mood
A new experience-sampling study by researchers at Bielefeld University and the University of Warwick examined how momentary caffeine use relates to daily mood in real-world settings. Over periods of up to four weeks, 236 young adults in Germany completed brief smartphone surveys seven times a day, reporting their current mood and whether they had consumed a caffeinated drink in the previous 90 minutes. The real-life design—rather than an artificial laboratory setting—lets the results reflect everyday caffeine behavior.
Overall, participants reported clearer increases in positive affect—feeling happier, more enthusiastic, and more energetic—after recent caffeine consumption. Decreases in negative states such as sadness or upset were also observed but were smaller and less consistent than the rise in positive feelings. Unlike the morning-focused boost in positive affect, reductions in negative affect did not show a pronounced time-of-day pattern.
Perceived effect regardless of consumption habits
The study explored whether caffeine affects people differently depending on their usual intake or mental health. Lead investigators noted they were surprised by how consistent the relationship between caffeine and positive affect was across groups. Individuals with higher anxiety, depressive symptoms, or differing sleep quality showed similar short-term mood responses after caffeine as those without such issues.
Researchers also caution that people who experience adverse reactions to caffeine may self-select out of frequent use, and the sample did not include lifetime abstainers. That means extreme negative responders could be underrepresented in the findings.
Role of caffeine withdrawal symptoms remains unclear
The authors describe plausible biological mechanisms: caffeine blocks adenosine receptors, which promotes wakefulness and can indirectly increase dopamine activity in brain regions tied to reward and alertness. These neural effects are consistent with improved mood and greater energy following consumption.
However, it is uncertain how much of the morning mood improvement reflects the pharmacological action of caffeine itself versus relief from mild overnight withdrawal in habitual users. Even moderate consumers can experience temporary withdrawal after sleep, and the first caffeinated drink of the day may restore baseline alertness and mood for that reason.
Caffeine consumption: a universal habit
Caffeine is one of the most widely used psychoactive substances worldwide; estimates suggest a large majority of adults regularly consume caffeinated beverages. The use of naturally occurring stimulants has deep roots in human history, and even non-human animals show preferences for caffeine-containing nectar in some ecological contexts.
At the same time, the researchers emphasize moderation. Regular high intake can foster dependence and increase the risk of adverse effects, while consuming caffeine late in the day may disrupt sleep and undermine overall wellbeing.
About this caffeine, mood, and neuroscience research news
Author: Jörg Heeren, Bielefeld University
Source: Bielefeld University (press release summarizing research conducted with collaborators at the University of Warwick)
Contact: Jörg Heeren – Bielefeld University
Image: Image credit: Neuroscience News
Original research: The findings were reported as an open-access article in Scientific Reports titled “The association of caffeine consumption with positive affect but not with negative affect changes across the day” by Sakari Lemola and colleagues.
Abstract
The association of caffeine consumption with positive affect but not with negative affect changes across the day
Caffeine is known for stimulating the central nervous system, improving cognitive performance, and altering affective states. Most evidence comes from controlled laboratory studies, while caffeine’s effects in everyday life are less well documented. This study used experience sampling to examine momentary links between caffeine intake and mood in naturalistic settings, accounting for time of day, individual differences, and context.
Across two samples of young adults monitored over 14–28 days, caffeine intake was associated with subsequent increases in positive affect; associations with reductions in negative affect were weaker and less consistent. The positive association was strongest during the morning hours, within the first 2.5 hours after awakening, and was moderated by tiredness and social context. Overall, the results suggest caffeine plays a meaningful role in modulating everyday mood, particularly early in the day.