Does your morning coffee or tea really boost your mood? Here’s what science says

By Priyanjana Pramanik, MSc.Reviewed by Susha Cheriyedath, M.Sc.Aug 6 2025

New research shows your morning cup of caffeine can lift your spirits, but when and how you drink it, and who you’re with, makes all the difference.

Study: The association of caffeine consumption with positive affect but not with negative affect changes across the day. Image Credit: Brian A Jackson / Shutterstock

In a recent article published in the journal Scientific Reports, researchers investigated the relationship between caffeine consumption and emotional states in everyday life, examining whether this relationship varies by context, individual characteristics, and time of day.

They found that caffeine intake was generally followed by a small-to-moderate increase in positive emotions, particularly when consumed within the first 2.5 hours after waking up, with a smaller but significant uptick around 10–12.5 hours after waking, though social context and tiredness influenced the strength of these associations.

Background

Caffeine is widely consumed worldwide and is known for its ability to boost mood, performance, and alertness. While laboratory studies support these benefits, less is known about how caffeine affects emotional states in real-world settings.

Caffeine acts as a stimulant by blocking adenosine, a brain chemical that promotes drowsiness and is linked to depression and anxiety. By preventing adenosine from working, caffeine boosts noradrenaline and dopamine, likely enhancing mood.

These effects could be strongest in the morning when people are most tired and vulnerable to sleep inertia. However, some evidence suggests that caffeine may also cause anxiety or sleep disturbances, especially in sensitive individuals or when consumed in high doses or later in the day. Moreover, emotional responses to caffeine may be shaped not just by biology but by context, such as whether it is consumed alone or socially.

In this study, researchers set out to explore how caffeine intake influences momentary emotional experiences, referred to as affect, during daily life. The researchers also explored how this relationship is shaped by factors like time of day, individual variations in sleep quality, caffeine dependence, mental health, and social context.

About the Study

The researchers hypothesized that caffeine would be associated with increased positive and decreased negative affect and that these effects would be strongest shortly after waking. The other questions were exploratory due to limited prior research.

To test these hypotheses, they analyzed data from two experience sampling method (ESM) studies conducted in Germany. Participants aged 18–25 in the first study and 18–29 in the second study were recruited and asked to complete short smartphone-based surveys multiple times a day for two to four weeks.

The first study lasted 15 days, while the second study lasted 29 days. Participants reported whether they had consumed caffeine in the past 90 minutes, along with their mood, tiredness, sleep, social context, and daily routine. Surveys were randomly scheduled throughout the day, with a minimum 90-minute gap between prompts.

Baseline measures included typical caffeine intake (converted to mg using standard values), caffeine dependence, depressive symptoms, anxiety, and sleep quality. Participants also completed daily sleep diaries.

In total, 115 participants from the first study and 121 from the second study provided sufficient data. Multilevel models were used to test associations between caffeine intake and affective states, controlling for variables like sleep duration and timing. Moderators such as time of day, tiredness, social setting, workday status, and individual traits were examined.

Key Findings

Across both studies, participants reported consuming caffeine in approximately 16% of their surveys. Multilevel analyses revealed that caffeine consumption was significantly associated with higher momentary positive affect in both studies.

This association varied between individuals, particularly linked to increased feelings of enthusiasm in both samples and happiness and contentment in the second study. Caffeine was associated with lower negative affect only in the second study, including reduced feelings of sadness and upset, though not for worry, and the effect was small and inconsistent across studies.

The strength of the caffeine-positive affect link depended on time since awakening, with the most pronounced effects occurring within the first 2.5 hours after waking, declining thereafter, and showing a smaller but significant increase around 10–12.5 hours after waking. No time-of-day effects were observed for negative affect.

Individual differences such as caffeine dependency, habitual intake, depression, anxiety, or sleep quality did not moderate the caffeine-affect relationship.

However, momentary tiredness (current and prior) enhanced caffeine’s positive mood effects, while being around others reduced them. No contextual or physiological moderators influenced negative affect.

Conclusions

This study provides real-world evidence that caffeine enhances positive affect, especially shortly after waking, with no consistent or robust effects on negative affect. The morning effect remained strong even when using different time metrics (clock time, sleep midpoint). Notably, individual traits like caffeine sensitivity or mental health symptoms did not moderate these associations, while situational factors such as tiredness and social context did.

The findings suggest that caffeine’s mood-enhancing effects are strongest in the morning, potentially due to habitual consumption patterns, though the withdrawal reversal hypothesis remains contested in the literature, given evidence of mood boosts in non-habitual users or circadian rhythm influences. The second study’s stronger and more consistent effects are likely due to its larger sample size and timing during fewer pandemic-related restrictions compared to the first study.

However, limitations include reliance on self-reported data, a young and gender-skewed sample, a lack of exact caffeine timing, and no direct assessment of chronotype. Future studies should explore first daily consumption, withdrawal symptoms, and objective circadian measures.

In conclusion, caffeine is reliably linked to increased positive mood, especially in the morning, influenced more by contextual states than stable individual traits.