Sleep Deprivation and Memory

Memory is an important component of human function required for daily tasks and knowledge. For example, in order to drive to work, you need to remember a multitude of things, including where you kept your car keys, how to start the car, how to drive, and how to get there. It is hard to imagine that even such a simple task is entirely dependent on your memory. In order for memory to work, you need to learn and consolidate information, which the brain normally does while a person is asleep. 

On December 10th, Eitan Schechtman-Drayman discussed how memory consolidation can be enhanced with sensory cues during sleep. In the clinical review that was discussed, "State of the art on targeted memory consolidation: Sleep your way to enhanced cognition" by Daphne Schouten, an olfactory cue was exposed to participants while they were asleep. It was found that participants that were exposed to the olfactory cue performed better in retrieval of declarative memory when compared to those that were not. 

A different study, "Slow-wave and REM sleep deprivation effects on explicit and implicit memory during sleep" by Sarah J. Casey et al., examines the influence of sleep deprivation on declarative and nondeclarative memory. Explicit, or declarative, memory requires conscious thought whereas implicit, or nondeclarative, does not. In this study, participants were either deprived of slow-wave sleep or rapid eye movement sleep through various nights and the subsequent effects on the consolidation of explicit or implicit memory was examined. It was found that deprivation of slow-wave sleep impacted the consolidation of explicit memories, particularly for visuospatial information and explicit verbal recall. Although deprivation of rapid eye movement sleep did not affect explicit visuospatial information, it was found that it had an impact on explicit verbal recall. Neither slow-wave sleep nor rapid eye movement sleep had an effect on implicit verbal recall or other types of memory, such as short-term and working memory. 

As stated before, sleep is essential for memory consolidation and it can be enhanced based on particular sensory cues such as smell, as discussed by Drayman. On the other hand, sleep deprivation can hinder the formation of memories, particularly of explicit memory regarding verbal recall and visuospatial information. 

Casey, S. J., Solomons, L. C., Steier, J., Kabra, N., Burnside, A., Pengo, M. F., Moxham, J., Goldstein, L. H., & Kopelman, M. D. (2016). Slow wave and REM sleep deprivation effects on explicit and implicit memory during sleep. Neuropsychology, 30(8), 931–945. https://doi.org/10.1037/neu0000314

Schouten, Daphne I., et al. “State of the Art on Targeted Memory Reactivation: Sleep Your Way to Enhanced Cognition.” Sleep Medicine Reviews, vol. 32, 2017, pp. 123–131., doi:10.1016/j.smrv.2016.04.002.