Cognitive Restoration is a percentage score that estimates how much of your cognitive recovery need last night actually met. It is built from two specific stages—deep sleep and REM—measured against your personalized sleep need, not a generic eight-hour target. A high percentage means the night delivered the structure your brain needed; a low one means something in duration, timing, or continuity cut into the stages that matter most for cognition.
Deep sleep clears metabolic byproducts and consolidates memory; REM supports learning, emotional regulation, and creative recombination. Light sleep contributes too, but deep and REM are the load-bearing stages for next-day cognition. Two nights with the same total hours can produce very different Cognitive Restoration scores depending on how much of each stage actually landed.
We compare the deep and REM sleep you got against the deep and REM you would expect at your full personalized sleep need. The result is expressed as a percentage—100% means the cognitive stages were fully covered for someone with your need; lower scores mean a proportional shortfall. The score is personalized: your sleep need is not the same as someone else's, so neither is your target.
High scores typically follow nights that were both long enough and well-structured—stable bedtime, few wake episodes, no late-evening alcohol. Lower scores tend to track with cut-short nights, fragmented sleep, or compressed REM from late bedtimes. One low night is noise; a week of low Cognitive Restoration is a real signal that demanding cognitive work will cost more than usual.
Treat Cognitive Restoration as a forward-looking gauge for the kind of work that depends on executive function and memory: deep focus blocks, learning, decisions you will not get to redo. On high-restoration days, lean into that work. On low days, protect easier tasks and prioritize the inputs—sleep timing, wind-down, light, and avoiding late alcohol—that move the score back up over the next few nights.
Sleep Score answers whether you got enough sleep overall; Cognitive Restoration zeroes in on the part of that sleep your brain depends on for the next day's thinking. Pair them with Recovery Score for a full readout of where the night left you—physically and cognitively.