What is fragmented sleep prevented from achieving, even if the total time spent in bed is sufficient?

Answer

Cycling effectively through the deep SWS and REM stages

Sleep architecture matters greatly; constantly interrupted or fragmented sleep inhibits the brain's ability to cycle properly through the necessary deep Slow-Wave Sleep (SWS) and REM stages required for waste clearance and memory integration.

What is fragmented sleep prevented from achieving, even if the total time spent in bed is sufficient?
brainSleeprestfunctioncognition