The relationship between daytime sleepiness and working memory performance in Russian adolescents: evidence from the Backward Digit Span task

Daytime sleepiness is a common experience during adolescence and has been linked to decrements in cognitive performance. However, evidence regarding its association with verbal working memory remains limited. The present study examined whether higher daytime sleepiness, as measured by the Pediatric Daytime Sleepiness Scale (PDSS), is related to lower working memory performance in adolescents. A total of 880 adolescents (436 males, 444 females; M age = 14.5, SD = 1.4) completed the PDSS and a computerized Backward Digit Span (BDS) task assessing verbal working memory. The main outcome measures were the longest correctly recalled sequence and the number of correct responses. Linear regression models were used to test whether PDSS predicted BDS performance while controlling for age and sex. Additional analyses compared participants with Low (PDSS 16) and High (PDSS ≥ 16) levels of daytime sleepiness. Higher PDSS scores were associated with shorter Backward Digit Span sequences ( β = −0.043, p = 0.004) and fewer correct responses ( β = −0.035, p = 0.052). Adolescents with high PDSS scores performed significantly worse than their low-PDSS peers ( β = −0.43, p = 0.027). Age positively predicted BDS outcomes, and females outperformed males. Daytime sleepiness showed a small but consistent negative relationship with verbal working memory capacity in adolescence. These findings suggest that even moderate increases in daytime sleepiness may reduce the efficiency of cognitive control processes during this developmental period.