Scientists Find Drinking This Much Coffee May Lower Stress, Improve Mood

The association between the two—coffee and mental health disorders—was J-shaped, meaning the lowered risk took off when coffee was introduced, and lingered at around two to three daily cups. But at five daily cups or higher, the apparent benefits faded, and for mood disorders, the risk trended higher, “which fits with what is seen clinically, when caffeine becomes excessive,” explains Kyra Bobinet, M.D., M.P.H., a behavioral health expert.

Participants reported the type of coffee they drank—instant, ground, or decaf—and the benefits weren’t seen in decaf drinkers. Researchers also adjusted for age, sex, ethnicity, education, socioeconomic status, smoking, alcohol, tea intake, sleep, physical activity, body mass index, hypertension, and type 2 diabetes to reduce confounding effects. They also noted participants’ genetics and metabolization of caffeine, which ultimately didn’t seem to matter.

Of course, because the coffee tendencies were self-reported and only collected once at baseline, there is a margin of error in these findings, as habits can change over time, notes Dr. Bobinet. They simply denote a correlation or relationship between the two variables—coffee consumption and mood/stress disorders.

How might coffee lower stress?

Put simply, it all comes down to inflammation—or lack thereof. Both Dr. Bobinet and Alexander Leritz, R.D., registered dietitian at JM Nutrition, note coffee’s antioxidant content, which may work to combat inflammation and, therefore, disease of all kinds.

“Mechanistically, coffee is much more than caffeine—it contains hundreds of bioactive compounds, including polyphenols and chlorogenic acids, that have antioxidant and anti‑inflammatory effects and independently may support brain health over time,” says Dr. Bobinet. The connection between coffee and a lower risk of mental health issues may be explained by its effects on things like kidney function, liver function, and fat metabolism. These are processes that antioxidants in coffee may help support, she notes.

To dig even deeper, “from a neurobiology standpoint, caffeine primarily blocks adenosine (A1 and A2A) receptors in the brain, which indirectly boosts dopamine signaling,” Dr. Bobinet explains. Dopamine is known as the “feel-good” hormone that is involved in a lot of higher executive functioning. “This can acutely improve alertness, motivation, and perceived energy, experienced as improved mood and resilience to stress,” she concludes.

It’s worth noting that this is not a new area of research, says Leritz, and previous studies have suggested a well-established link between caffeine, inflammation, and mood disorders.

The bottom line

“My main takeaway is that, for most middle‑aged adults, moderate daily coffee—around two to three cups—is unlikely to be harmful and may actually be associated with a lower long‑term risk of clinical mood and stress‑related disorders,” says Dr. Bobinet. “But this is not a green light to ever medicate stress or depression with coffee. It’s one lifestyle factor among many, and this study does not prove that coffee itself is the protective agent, rather than overall healthier behaviors that tend to cluster with moderate coffee drinking.”

Leritz agrees. “If you are someone who enjoys a cup or two of joe in the morning, there is no reason to feel guilty about it,” he adds. “However, if you are someone who is sensitive to the effects of caffeine, it may still be beneficial to work within the parameters of your individual tolerance so as not to disrupt sleep or exacerbate underlying anxiety.” Be sure to speak with your physician before upping your caffeine intake, as it may impact medications and certain health conditions.