With the explosion of digital media and technologies, scholars, educators and the public have become increasingly vocal about the role that an ‘attention economy’ has in our lives. The rise of the current digital culture coincides with longstanding scientific questions about why humans sometimes remember and sometimes forget, and why some individuals remember better than others^{, , , –}. Here we examine whether spontaneous attention lapses—in the moment^{, , , , –}, across individuals^{, –} and as a function of everyday media multitasking^{, , –}—negatively correlate with remembering. Electroencephalography and pupillometry measures of attention^, were recorded as eighty young adults (mean age, 21.7 years) performed a goal-directed episodic encoding and retrieval task. Trait-level sustained attention was further quantified using task-based and questionnaire measures^,. Using trial-to-trial retrieval data, we show that tonic lapses in attention in the moment before remembering, assayed by posterior alpha power and pupil diameter, were correlated with reductions in neural signals of goal coding and memory, along with behavioural forgetting. Independent measures of trait-level attention lapsing mediated the relationship between neural assays of lapsing and memory performance, and between media multitasking and memory. Attention lapses partially account for why we remember or forget in the moment, and why some individuals remember better than others. Heavier media multitasking is associated with a propensity to have attention lapses and forget.