Sleep is not merely a period of rest — it is an active process essential for brain health and cognitive function. During sleep, the brain consolidates memories, removing unnecessary information while strengthening important connections. Recent research has revealed that the brain's glymphatic system, a waste-clearance network, is most active during sleep, flushing out toxic proteins linked to Alzheimer's disease. Adults generally need seven to nine hours of sleep per night, yet modern lifestyles, artificial lighting, and screen time have reduced average sleep duration significantly, raising concerns about long-term public health consequences.

How many hours of sleep do adults generally need?