Slow-Wave Activity Enhancement to Improve Cognition

Slow-wave activity (SWA), and its coupling with other sleep features, reorganizes cortical circuitry, supporting cognition. This raises the question: can cognition be improved through SWA enhancement? SWA enhancement techniques range from behavioral interventions (such as exercise), which have high feasibility but low specificity, to laboratory-based techniques (such as transcranial stimulation), which have high specificity but are less feasible for widespread use. In this review we describe the pathways through which SWA is enhanced. Pathways encompass enhanced neural activity, increased energy metabolism, and endocrine signaling during wakefulness; also direct enhancement during sleep. We evaluate the robustness and practicality of SWA-enhancement techniques, discuss approaches for determining a causal role of SWA on cognition, and present questions to clarify the mechanisms of SWA-dependent cognitive improvements. NREM sleep contributes to consolidation of memories and restored executive function. The involvement of NREM features in cognition depends on SWA. Enhancing SWA in older adults and clinical populations with cognitive deficits may effectively improve cognition through sleep. Techniques promoting energy metabolism (such as exercise) and endocrine signaling (such as growth hormone) are known to enhance SWA and cognition. SWA may therefore mediate the link between these approaches and cognition. Brain and body heating, and transcranial stimulation during sleep, are promising approaches to identify the functions of SWA that improve cognition.