Developmental delay is a significant concern for infants born with complex congenital heart disease (CCHD). Environmental exposures (e.g., excessive light and sound exposure, sleep disruption) in neonatal intensive care are associated with poor developmental outcomes. However, the environmental experience of newborn infants in cardiac care is unknown. The aim of the study was to examine the feasibility of continuous environmental data collection (i.e., light and sound exposure, sleep pattern) in pediatric cardiac care units and describe the environmental experience of three hospitalized infants with CCHD. A case series of three infants undergoing cardiac surgery for CCHD within the first month of life was performed. Measures of light, sound, and sleep were collected in 24-hour periods on three to four separate hospital days. For each day, light and sound meters were attached to the hospital bed, and an actigraphy band was placed on the infant's lower leg to measure sleep/wake states. Feasibility of continuous environmental data collection was assessed through acceptability of data collection for families and clinical staff, usability of data collection equipment for research staff, and study protocol adherence. Descriptive statistics were used to calculate the count and duration of episodes of excessive light and sound exposure, hourly levels of light and sound exposure, total sleep time, duration of individual sleep episodes, and number of arousals from sleep. Although continuous environmental data collection was generally acceptable to families and clinical staff, multiple usability issues were identified by research staff, and study protocol adherence was variable. Missing data were a major limitation. User error during equipment setup was a main contributor to missing data. Infants experienced frequent episodes of sound exposure above recommended maximum levels, whereas light exposure generally remained below recommended maximum levels. Infant sleep patterns were highly fragmented, with frequent arousals and short duration of individual sleep episodes. Lessons learned during preliminary data collection with the infants in this case series will inform methods and prevent missing data in future, large-scale studies of this vulnerable, hard-to-recruit population. Data reflect a cardiac care environment characterized by excessive sound exposure and highly disrupted sleep. These environmental stressors may affect developmental outcomes in infants with CCHD.