Sleep Regularity Modulates the effect of Sleep Duration onLong-Term Memory Function in Healthy Undergraduates

Sleep deprivation is common amongst the student community. Poor sleep quality has been associated with reduced cognitive health, specifically a reduction in the ability to form and consolidate long-term memories, which leads to poor academic performance. However, while severe sleep reduction has been studied, the effect of small amounts of sleep loss on cognition is not as well understood. Additionally, while reduced sleep duration has been shown to negatively affect long-term memory, sleep regularity is is also emerging as critical aspect of sleep health. However, it is unknown how sleep duration and regularity interact to shape memory consolidation. Lastly, it is difficult to compare and generalize memory test data due to the lack of standardized cognitive tests. To address this gap, 29 undergraduate students wore sleep tracking watches over three weeks while completing a weekly cognitive test, the Seattle-Groningen Memory Assessment (SGMA). The SGMA is a model-based cognitive assessment with high sensitivity and specificity capable of reliably tracking episodic memory longitudinally. Results show that sleep deprivation is directly correlated to memory performance the following day, with reduced sleep leading to worse memory performance. However, the effect of sleep deprivation on memory performance is modulated by sleep regularity, with high sleep regularity having a compensatory effect on acute low sleep duration. Sleep regularity alone did not affect cognitive scores. These findings act as a demonstration of the multifaceted nature of sleep on memory, and highlight the importance of regularity in situations where sleep duration might be limited.