Lighter Sleep May Compromise Memory

Healthy adults typically spend one-quarter of the night in deep, non-rapid-eye-movement (REM) sleep. Slow waves are generated by the brain’s middle frontal lobe. Deterioration of this frontal region of the brain in elderly people is linked to their failure to generate deep sleep.  Matthew Walke, from the University of California/Berkeley (California, USA), and colleagues have identified a  link brain deterioration, sleep disruption and memory loss.  The team observes that slow brain waves generated during the deep, restorative sleep we typically experience in youth play a key role in transporting memories from the hippocampus – which provides short-term storage for memories – to the prefrontal cortex’s longer term “hard drive.”  However, in older adults, memories may be getting stuck in the hippocampus due to the poor quality of deep ‘slow wave’ sleep, and are then overwritten by new memories.  The discovery that slow waves in the frontal brain help strengthen memories paves the way for therapeutic treatments for memory loss in the elderly.