Lyubomirsky et al., 2005, Study 1, described in Lyubomirsky et al., 2005: Performing five acts of kindness per day over six weeks increased happiness among college students over this period
Lyubomirsky, S., Sheldon, K. M., & Schkade, D. (2005). Pursuing happiness: the architecture of sustainable change. Review of general psychology, 9(2), 111.Download PDF
Asking college students to perform 5 acts of kindness on a single day each week for 6 weeks increased happiness over this period, as compared to both a no-treatment control group and students asked to perform 5 acts of kindness spread over the week.