Research Suggests Partial Activation of Sleep Functions in Awake Brain Regions

In the study, researchers found that inducing a specific sleep-like brain pattern in awake mice could mitigate some cognitive impairments caused by sleep deprivation. These findings challenge the notion that the brain must be in a complete sleep state for vital neural maintenance tasks. Instead, they suggest local restorative functions can be activated while other regions of the brain remain alert and responsive.

Chiara Cirelli, M.D., Ph.D., a professor of psychiatry at the University of Wisconsin-Madison and corresponding author of the study, explained, “What we’re essentially doing is forcing sleep in a local region of the brain. While that part is solidifying memories and restoring learning capacity, other parts stay aware and connected to the environment.” This phenomenon is somewhat akin to dolphins, which sleep with one hemisphere of their brain at a time.

Non-rapid eye movement (NREM) sleep, which represents about 80% of adult sleep, plays a crucial role in reinforcing neural connections related to memory. During this phase, the brain strengthens key connections, discards less relevant ones, and formulates space for new learning.

Building on earlier findings, which noted that sleep-deprived rats and humans could exhibit brief episodes of slow-wave activity—a characteristic of NREM sleep—even while awake, researchers aimed to extend this activity. In the recent study, they employed light-activated implants and genetic modifications to generate rhythmic cycles of activity in one hemisphere of the brains of sleep-deprived mice, simulating NREM sleep patterns.

Subsequent observations revealed that stimulated brain regions exhibited decreased slow-wave activity during actual sleep, implying these areas had less need for recovery. The apparent benefits were linked not to an overall reduction in neuronal activity but to the specific alternation of activated and inactive phases.

Behavioral tests focusing on tactile memory showed that sleep-deprived mice receiving stimulation in motor and sensory areas performed comparably to well-rested mice, while those not receiving stimulation performed significantly worse.

Cirelli and her team are now exploring whether similar effects can be achieved in humans through less invasive transcranial stimulation techniques. Amy Bany Adams, Ph.D., acting director of the NIH’s National Institute of Neurological Disorders and Stroke (NINDS), remarked, “This research further decodes why we sleep and how we learn, which brings us a step closer to understanding how to better prevent and treat cognitive decline.”

The study was published in Nature Neuroscience with the reference: “Induction of cortical on/off periods in awake mice fulfills sleep functions” by Kort Driessen, Fabio Squarcio, Giulio Tononi, and Chiara Cirelli on June 8, 2026.