Inclusion Criteria:  (1) aged 18 years old or older, (2) frontline registered nurse or licensed practical nurse practising in the United States, (3) has at least daily access to their own Apple iPhone (version 5 or later) or Android phone, and (4) have posttraumatic stress disorder (PTSD) symptoms (must have a score of 33 or above on the PTSD Checklist for DSM-5)  Exclusion Criteria:  (1) Those who have a score of 32 or below on the PTSD Checklist for DSM-5, and (2) healthcare workers that are not RNs or LPNs