Sleep prevents brain phosphoproteome disruption to safeguard survival.

Prolonged sleep deprivation (Pr-SD) causes death in many species. While various mechanisms related to sleep regulation or this fatal consequence of sleep loss have been identified, the core molecular basis linking Pr-SD-induced lethality and sleep homeostasis remains unknown in mammals. A critical "point of no return (PONE)" status in Pr-SD subjects is highlighted in classic research, and characterizing PONE status could help uncover this mystery. Using a Pr-SD model and a reliable PONE status prediction method, we show that mice in PONE exhibit an inability to enter natural sleep, and significant disruptions in brain phosphoproteome, independent of deprivation time but closely linked to PONE status. Brain kinase or phosphatase dysfunction influences PONE status development and leads to corresponding sleep aberration concurrently. Daily 80-min recovery sleep significantly delays PONE onset and restores brain phosphoproteome. The harmful effects of excessive kinase activity on PONE development can be eliminated by combining recovery sleep and compensatory phosphatase expression. We conclude that sleep is crucial for maintaining brain phosphoproteome homeostasis, whose disruption may impact both Pr-SD-induced lethality and sleep regulation.