0228 The Rate of Forgetting During Wake Is Not Exacerbated by a Night of Total Sleep Deprivation

Abstract Introduction Sleep has been shown to slow the rate of forgetting compared to a period of wake, but no studies to date have explored whether total sleep deprivation (TSD) also moderates the rate of forgetting compared to rested wakefulness. We investigated how well participants could retain information throughout the day on the day before, during, and the day after TSD. Methods 16 individuals (ages 18-38; mean age 25.8y ± 7.9y; 8 males, 8 females) completed a 4-day/3 night in-laboratory sleep study. Following a baseline 10h sleep opportunity, participants underwent a 38h TSD period followed by a 10h recovery sleep opportunity. Sleep periods were 22:00-08:00. Each day in the lab, participants were presented with a new list of words at around 09:30 and were asked to recall the words immediately, 4h, and 6h after study. Results A mixed-effects ANOVA with fixed effects of session (1, 2, or 3), test (immediate, 4h, or 6h later), and their interaction, with a random intercept over subjects, revealed a significant effect of test (F=22.23, p < 0.001), but no significant effect of session or session x test interaction (F< 2.26, p>0.10). Relative to immediate testing, recall decreased 27.3% at 4h and 26.1% at 6h. Post-hoc tests on the effect of test and the session x test interaction revealed that accuracy on the immediate recall test was better than accuracy 4h or 6h later (p< 0.001), but only in sessions 2 and 3. The pattern was similar in session 1, but not statistically significant. Conclusion In line with the established forgetting curve, participants had better memory for the words at immediate recall than at 4 and 6h later. Contrary to expectations, sleep deprivation did not appear to exacerbate the forgetting rate, even though participants had been awake for 25.5h at study. Future research should include tests at greater delays. Additionally, it should investigate whether chronic and acute sleep deprivation have differential effects on the forgetting rate. Support (if any) Google