Yom Kippur, the 'Day of Atonement' is considered the holiest day of the year in Judaism, and is sometimes known as the 'Sabbath of Sabbaths'. During Yom Kippur, Jews traditionally engage in a day-long fast, confession, and intensive prayer. Fasting during Yom Kippur represents a confluence of different religious and spiritual elements, including repentance (i.e., accepting responsibility for past wrongs, feeling remorse, and realigning oneself with moral imperatives), reappraisal (i.e., finding meaning and opportunities for growth in stressful situations), and recommitment (i.e., renewing commitments to character growth, God, interpersonal relationships, and physical well- being). In this multi-method, multi-year research project, the effects of religious fasting during Yom Kippur will be investigated.

The project, directed by Adam Cohen and Kathryn A. Johnson at Arizona State University hypothesizes that fasting, when situated within religious and spiritual framework, will predict greater flourishing. The project also hypothesizes that repentance, reappraisal, and recommitment — which, together, reflect what the researchers call 'spiritual transformation' — mediate the relationship between fasting and flourishing, and that deep self-reflection and religious group participation will moderate the relationship between fasting and flourishing. Flourishing is conceptualized as involving  the virtues of temperance, humility, and generosity; subjective well-being, including social cohesion, spiritual well-being, and life satisfaction; and physical well-being. A number of individual differences variables will also be assessed as exploratory moderator variables.

The project will begin with engagement with a panel of practitioners from multiple faith traditions including Jewish rabbis, a Christian minister, and a U.S. Navy chaplain who will provide input, approve study designs, and meet annually after the project begins to discuss results and findings. Five studies will examine the impact of three Yom Kippur celebrations over three years.

Outputs of the project will include manuscripts for peer-reviewed scientific or multidisciplinary journals, a theoretical article relating findings to the intellectual history of the study of flourishing, a popular article for Jewish clergy, presentations at academic conferences, a symposium, and a brief report for practitioners. Through its research activities and outputs, the project aims to improve scientific and lay understanding, especially among Jewish people, of the psychological benefits, causal mechanisms, and contextual influences of fasting. It is hoped that the project will illuminate the value of ancient wisdom and beneficial practices which might in turn renew a desire to know and experience more in terms of the sacred through practice, over and above merely focusing on beliefs.