0109 Slow-Wave Sleep Mediates the Compensatory Effects of Acute Moderate-Intensity Exercise on Long-Term Memory Deficits in Sleep Restriction

Abstract Introduction While adequate sleep promotes optimal cognitive functioning, sleep deprivation impairs memory functions. Physical exercise enhances sleep architecture, including slow-wave sleep (SWS), and enhances memory, and may thus counteract the detrimental effects of sleep loss on memory. We evaluated whether acute moderate-intensity exercise compensates for the detrimental effects of nighttime sleep restriction on declarative memory and if SWS mediates the compensatory effect in healthy young adults. Methods Eighty-eight healthy young adults (52% female; 24.0 ± 3.8 years) were randomly assigned to one of four groups based on exercise and sleep opportunity: average sleep only (S8, 8.5 hours/night), restricted sleep only (S5, 4.5 hours/night), and moderate-intensity exercise before restricted sleep (ExS5) or average sleep (ExS8). Participants completed either a 30-minute evening cycling at 55-60% of their individual maximal oxygen consumption or seated rest (7:00 p.m.) prior to learning 80 face–name pairs (10:00 p.m.), followed by immediate recall and delayed recall involving 120 face-name pairs (80 studied plus 40 new faces) after polysomnography-recorded sleep. Results We found a significant exercise × sleep interaction for delayed recall performance (discriminability index, d’; p = 0.033, ηp² = 0.056) and the difference between delayed and immediate recalls (p = 0.012, ηp2 = 0.077). Post hoc analyses showed that the delayed retrieval d' of ExS (0.07 ± 0.89) was not statistically different from those of the S8 (0.58 ±1.20, p = 0.115) and ExS8 (0.21±1.30, p = 0.747) but was significantly higher than the S5 (-0.60 ± 1.38, p = 0.028). Similarly, the delayed retrieval d' of S5 was significantly lower compared to those of S8 (p < 0.001) and ExS8 (0.21± 0.30, p = 0.029). Likewise, the difference in d' of ExS5 (0.36 ± 0.79) was significantly higher than the S5 (-1.13 ± 1.02, p < 0.001). The percentage of SWS mediated the compensatory effects of the ExS5 vs. S8 condition on long-term memory (B = 20.38, SE = 16.49, 95% bootstrap CI (5.70, 59.99)). Conclusion These results suggest that acute moderate-intensity evening exercise enhances sleep-dependent memory consolidation and compensates for the detrimental effects of sleep restriction on long-term declarative memory, through mechanisms involving slow-wave sleep. Support (if any)