The effect of sleep-specific brain activity versus reduced stimulus interference on declarative memory consolidation.

Studies suggest that the consolidation of newly acquired memories and underlying long-term synaptic plasticity might represent a major function of sleep. In a combined repeated-measures and parallel-group sleep laboratory study (active waking versus sleep, passive waking versus sleep), we provide evidence that brief periods of daytime sleep (42.1 ± 8.9 min of non-rapid eye movement sleep) in healthy adolescents (16 years old, all female), compared with equal periods of waking, promote the consolidation of declarative memory (word-pairs) in participants with high power in the electroencephalographic sleep spindle (sigma) frequency range. This observation supports the notion that sleep-specific brain activity when reaching a critical dose, beyond a mere reduction of interference, promotes synaptic plasticity in a hippocampal-neocortical network that underlies the consolidation of declarative memory.