A study by Fudan University has found that drinking 2 to 3 cups per day may lower stress, while less than one cup of coffee per day is found to have a protective effect. The study, which tracked over 460,000 people for 13 years, found that this benefit held steady across different types of coffee, including decaf. The relationship between coffee and mental health is more nuanced than one could perceive, with moderate consumption consistently beneficial.