Many young adults report sleep problems, including insufficient sleep and poor sleep quality. Young adults are heavily reliant on electronic devices, even using them during bedtime with adverse effects on sleep. Given the importance of adequate sleep, the present study examined the daily association between using electronic devices during bedtime and sleep in a diverse sample of young adults with poor sleep. We analyzed data from a pilot randomized controlled trial in which young adults with poor sleep [n = 46; 84% female; mean age 19.3 (SD = 2.9); 30% Asian, 19% Black/African American, 9% multiracial; 34% Hispanic/Latino] wore an electronic sleep tracking device (Fitbit Charge 3) and completed daily sleep diaries including questions about sleep and bedtime routine for 4 weeks following a behavioral sleep intervention. The effect of bedtime device use on sleep latency-time needed to fall asleep-and sleep duration was estimated by generalized linear mixed models (GLMM), adjusting for weeknights/weekend nights. Bedtime device use on a given night was significantly associated with shorter self-reported sleep duration (b = - 19.80, p = .011), but not with sleep latency. Concordance between the self-reported and Fitbit-measured sleep variables was low, and bedtime device use was not associated and Fitbit-measured sleep variables. Using electronic devices before bed negatively affected self-reported sleep duration the following night. This finding highlights the importance of minimizing nightly device use among young adults with poor sleep and suggests that the inconsistency between self-reported sleep and device use warrants further investigation.