The research team, led by Emily Hokett of Florida Atlantic University together with colleagues at the University of Texas at Austin and the Georgia Institute of Technology, set out to answer a question that has been largely overlooked in sleep science: do the well-documented sleep disparities between Black and White adults translate into measurable differences in how well memories hold up over time? Epidemiological studies have repeatedly shown that older Black adults perform worse on standardized memory tests than older White adults, and that their memory performance appears more sensitive to poor sleep. Yet most of the underlying sleep-memory research has been conducted in predominantly White samples, leaving a major gap in understanding.

To close that gap, the team recruited 214 adults aged 18 to 74 through the online platform Prolific, deliberately oversampling Black participants, who made up 26 percent of the sample, roughly double their share of the U.S. population. Each participant completed two sessions on consecutive days. In the first session, they filled out questionnaires measuring sleep quality, depressive symptoms, and experiences of discrimination, and then studied 64 pairs of images, each pairing a common object with a contextual image such as a face or a scene. Participants rated how easy it would be to imagine the two items together in a natural setting, a technique designed to encourage deep encoding of the object-context associations. Immediately afterward, they took a retrieval test in which half of the pairs appeared as originally studied and half had been recombined with a different context from the same category.

The second session, held 24 to 36 hours later, is where the task became genuinely demanding. Before being tested on the original pairs, participants first learned and were tested on a new set of interference pairs, in which half of the previously studied objects were re-paired with a different type of context, for example an object once paired with a city scene now paired with a face. Only then did they take the delayed test on the original pairs, requiring them to ignore the fresh, competing associations and recover the ones formed the day before. This design deliberately taxed cognitive control, the top-down prefrontal machinery that prior research suggests benefits most from sleep-dependent consolidation.

The outcome measure was memory retention, calculated as the difference in signal-detection sensitivity, or d-prime, between immediate and delayed retrieval. Because some forgetting is expected, smaller negative values indicated better retention. A meta-analysis has shown that this kind of retention measure is more sensitive to sleep than many other memory metrics, making it an ideal probe for the question at hand. When the interference and non-interference conditions showed no reliable differences, the researchers collapsed across them for the main analyses.

The central result was striking. After controlling for age and years of education, Black adults showed a significant association between poorer self-reported sleep quality, measured with the Pittsburgh Sleep Quality Index, and poorer memory retention. White adults showed no such relationship. In other words, the quality of a Black participant’s habitual sleep over the prior month predicted how well their memories survived the delay, even under interference, while sleep quality carried no detectable weight for White participants. Notably, age did not moderate the effect in either group, a finding the authors attribute in part to the limitations of self-reported sleep and the online recruitment of a relatively well-educated sample.

The study then probed why this disparity might exist. Depression emerged as a strong correlate across the board: in both Black and White adults, higher depressive symptoms went hand in hand with poorer sleep quality. But depressive symptoms did not statistically mediate the sleep-memory link in either group, meaning they could not fully account for the association. Discrimination told a more nuanced story. Among Black adults, higher self-reported discrimination, whether measured as the number of distinct discriminatory events or their frequency on the Experiences of Discrimination Scale, was associated with poorer sleep quality, higher depressive symptoms, and, for discrimination frequency, poorer memory retention. Yet formal mediation tests found no significant indirect effects, so discrimination and depression appear to travel alongside the sleep-memory association rather than fully explaining it.

The authors interpret these patterns as evidence of an interlocking system of racially patterned stress. Discrimination is known to degrade sleep, and racism-related vigilance, the exhausting anticipation of racist events even when none occur, has been linked in the team’s earlier work to poorer sleep among Black adults. Depression is bidirectionally tied to sleep disturbance and is associated with reduced hippocampal volume, the very structure that supports episodic memory consolidation. Large epidemiological datasets, including the Health and Retirement Study, have shown that Black adults reporting more discrimination also show poorer episodic memory and faster memory decline over six years. The new study adds an experimental dimension to this picture, suggesting that chronic discriminatory stress may amplify the sensitivity of memory retention to sleep quality.

The study has clear limitations that the authors acknowledge. Sleep was measured by self-report, which is subject to recall bias and can diverge from objective measures such as actigraphy or polysomnography. The design was cross-sectional, so it cannot establish whether poor sleep drives memory decline, whether depression disrupts both, or whether the arrows point the other way. Online recruitment may have drawn a sample with higher socioeconomic status than the general population, potentially muting age-related effects, and the modest number of Black participants, 56, limits statistical power for detecting small mediation effects. The researchers call for in-person replication with objective sleep monitoring and community-based samples.

Even with those caveats, the implications are significant. This is the first experimental study to demonstrate that associative memory retention, a hallmark of sleep-dependent consolidation, is reliably linked to habitual sleep quality in Black adults but not White adults, and the first to investigate discrimination and depression as candidate mechanisms. If poor sleep is one pathway through which social inequity becomes cognitive inequity, then interventions that improve sleep, and policies that reduce discrimination, could carry measurable benefits for brain health. The authors argue that sleep research should inform policy changes aimed at reducing discriminatory experiences, and that future studies should test whether such changes improve sleep, mental health, and memory, potentially narrowing racial and ethnic health disparities at their root.

Subject of Research: Associations between sleep quality, episodic memory retention, discrimination, and depression in Black and White adults

Article Title: Black adults show cross-sectional associations between sleep quality and episodic memory retention: an investigation of underlying factors

Article References: Hokett, E., Campbell, J., Arunmozhi, A., & Duarte, A. (2026). Black adults show cross-sectional associations between sleep quality and episodic memory retention: an investigation of underlying factors. Frontiers in Sleep, 5, Article 1968296. https://doi.org/10.3389/frsle.2026.1968296

Image Credits: AI Generated

DOI: 10.3389/frsle.2026.1968296

Keywords: sleep quality, episodic memory, memory retention, racial disparities, discrimination, depression, cognitive aging, memory consolidation, Pittsburgh Sleep Quality Index, health disparities, cognitive control, hippocampus