Everyone's brain produces brief bursts of sleep-like slow waves while awake. They're called “local sleep” — small cortical regions transiently dropping into a sleep-like state while the rest of the brain stays online. In neurotypical adults, they're infrequent and mostly inconsequential. In adults with ADHD, they happen significantly more often, and they predict attention lapses.
Published in JNeurosci (Pinggal et al., Monash University, March 2026), the study compared 32 unmedicated adults with ADHD to 31 neurotypical adults during a sustained attention task. The ADHD group showed more frequent slow-wave intrusions, and these intrusions correlated with slower reaction times, more errors, and more attention lapses. The relationship was specific: it wasn't general arousal, drowsiness, or fatigue. It was local cortical sleep during wakefulness.
The finding reframes what inattention means at the neural level. The standard model treats ADHD attention deficits as a failure of executive control — the prefrontal cortex not maintaining task engagement. The slow-wave finding suggests a different mechanism: the sensory and association cortices periodically going offline. The attention isn't lost by the controller. It's interrupted by the substrate.
The distinction matters because it changes what a treatment would need to do. Suppressing local sleep is a different target from enhancing executive control. Stimulant medications — the standard ADHD treatment — increase global arousal, which might work partly by reducing slow-wave intrusions. But nobody designed them for that purpose, and the 2025 finding that “ADHD drugs don't work the way we thought” suggests the mechanism-treatment alignment is looser than assumed.
The broader implication: attention is not purely a top-down resource allocated by a controller. It's partly a bottom-up property of cortical state. When the cortex locally falls asleep, attention fails — regardless of what the executive system intends. The will to focus doesn't override the nap.