Enhancement of spatial memories at the associative and relational levels after a full night of sleep and likelihood of dream incorporation
This study evaluated the effect of sleep in mediating the performance of associative and relational spatial memories in an immersive spatialised task. It also investigated how items presented during the task were incorporated into participants' dreams.
A total of 54 participants were assigned to either a wake or sleep condition in their home setting: 27 participants stayed awake during a normal day between the learning and the testing phases of a spatial task, while 27 other participants slept in their home according to their usual sleep schedule. Subjective dream experiences during the night were reported by the participants using a paper/pencil diary.
Results showed that memory performances for the testing phase were greater for the Sleep group at both associative and relational levels compared to an equivalent period of wake. The examination of dream reports revealed that 6 dream reports out of 17 (35.29%) collected in the Sleep group incorporated items related to the task.
To our knowledge, this study is the first to demonstrate a protective effect of sleep on associative and relational memory performance using an immersive spatialised VR task and with a full night's sleep occurring in a home setting that respected the participant's usual sleep schedule.
As a perspective, we proposed methodological improvements for future studies investigating dreams and their relationship with memory processes.