Feb 24, 2026Sleep Architecture in Aging: Why Deep Sleep Declines and How to Partially Restore ItSlow-wave sleep (deep sleep) declines approximately 2% per decade from early adulthood, dropping from roughly 20% of total sleep in young adults to under 5% in adults over 70. This decline is not simply reduced sleep duration — it represents a fundamental change in sleep architecture with consequences for metabolic health, memory consolidation, and cellular repair.