Nutrients: The Aroma of Coffee May Affect Mood

Five minutes of exposure to the aroma of freshly brewed coffee was associated with reductions in several measures of negative mood and a small change in brain electrical activity, according to a small study published in the journal Nutrients. Heart rate and heart rate variability, however, did not change significantly among the participants.

The study involved 20 healthy people aged 20 to 29 — eight men and 12 women. The experiments were conducted at Showa University of Pharmaceutical Sciences between March 2024 and March 2026.

For each participant, freshly brewed coffee was placed approximately 50 cm away. The participants calmly breathed and inhaled the aroma of the beverage for five minutes. Before and after exposure, the researchers assessed their mood using a standardized questionnaire and recorded brain electrical activity, heart rate, and heart rate variability.

After five minutes of exposure to the aroma, the overall mood disturbance score decreased. Individual scores for tension and anxiety, fatigue, confusion, and depression also declined, while a preliminary analysis showed a reduction in irritability. However, after adjustment for multiple comparisons, the decrease in irritability was no longer statistically significant. The participants’ vigor score did not change significantly.

The researchers also found a small increase in the so-called relaxation index, calculated from electroencephalography (EEG) data — from approximately 0.74 to 0.78. The authors emphasize that this measure reflects certain characteristics of brain electrical activity associated with relaxation, but is not a direct measure of a person’s state of relaxation.

Heart rate and heart rate variability did not change significantly before and after exposure to the aroma. The researchers also found no significant associations between changes in mood, brain activity, heart rate, and heart rate variability.

The authors note that the findings cannot be conclusively attributed to the effects of coffee aroma itself. The study did not include a control group, meaning that the participants’ condition may have been influenced by the calm environment, rest, repeated testing, expectations, or adaptation to the laboratory setting.