If only I could sleep, maybe I could remember

Abstract: Memory lies the ground for human cognitive skills, enabling complex social interaction, abstract thinking, and execution of precise motor skills. Development of these memory functions can be modified by several factors, including previous knowledge, reward, and sleep. In Paper I, skill level already when learning a motor skill determined whether the newly encoded memory would be enhanced during a subsequent post-learning period without training. Those already performing at a high level during learning gained less until recall, whereas those who performed at a lower level during learning demonstrated an enhanced improvement at recall.Thus, in Paper I we determined modulators of skill enhancement. In Paper II, we actively intended to modulate subsequent motor skill gain by delivering a praise immediately following learning. We found that praise had a positive effect on performance gain, which demonstrates that there are interventions that can easily be applied to enhance motor skill learning across time.Sleep is vital for healthy cognitive functions, and sleep disruption has not only been correlated with impaired cognitive function in the short-term, it has also been implicated as a risk factor for development of neurodegenerative disorders such as Alzheimer’s disease. In paper I, nighttime sleep between learning and recall of a motor memory was beneficial for learning compared to a daytime wake period. In Paper III, depriving participants from sleep negatively influenced performance on a working memory task; as did auditory distractions, but independent from sleep deprivation. However, working memory functions were not equally effected in women and men; working memory functions in women were more affected by sleep deprivation.Although it is well-known that sleep is good for health and well-being, in today’s modern society, most people have access to electricity and internet 24/7, and it is not uncommon to exchange sleep time with spending time in front of screen-based devices, such as smartphones. Access to screen-based devices in the evening and during the night are negatively correlated with a good night’s rest. In Paper IV, we did not find support for that the light emitted from those screens play a role for this negative correlation.