Brain Stimulation in Awake Mice Partially Offset Sleep Deprivation Effects, Study Finds
Researchers used light to mimic slow-wave activity in one brain hemisphere of sleep-deprived mice. Stimulated animals performed as well as rested mice on a memory task the next day.
New ScientistStimulating specific patterns of brain activity in awake mice produced some of the same effects as deep sleep, including improved memory performance after sleep deprivation. Researchers at the University of Wisconsin-Madison genetically engineered mice so that neuronal activity in one brain hemisphere could be switched off using light.
They implanted a probe into one half of each animal’s brain and kept the mice awake for five hours by giving them new objects to explore.
Near the end of the five-hour period, the team turned the light probe on and off repeatedly for 30 minutes to mimic the synchronized firing and silencing of neurons that occurs during non-rapid eye movement sleep. After the mice were allowed to sleep, recordings showed that the stimulated hemisphere did not display the usual signs of exhaustion caused by sleep deprivation.
“Because that small part of the brain did its decluttering while awake, it no longer needed extra deep sleep afterwards,” Chiara Cirelli said.
To test memory, the researchers placed the mice in a square box lined with carpet of uniform texture. After 15 minutes of exploration, the animals were divided into three groups: one allowed to sleep, one kept awake for an additional hour, and one kept awake for an additional hour while receiving the artificial slow-wave stimulation.
The next day, the mice returned to the box, now with a new texture on one side.
Sleep-deprived mice without stimulation spent similar amounts of time on both sides, indicating they could not distinguish the familiar environment from the novel one. Both the rested group and the stimulated sleep-deprived group spent more time on the new side. NREM sleep accounts for about 80 percent of total sleep time in adults.
During this stage the brain’s cortex repeatedly fires in unison and then quiets, a pattern known as slow-wave activity that has been linked to synaptic homeostasis. Vladyslav Vyazovskiy of the University of Oxford, who was not involved in the study, said it should be possible, at least in theory and to some extent, to replicate these results in humans.
He added that it would be fascinating to explore whether artificially inducing this activity during waking hours can produce a subjective feeling of being more refreshed.
The team plans to investigate whether comparable effects can be achieved in people using non-invasive transcranial electrical stimulation. Vyazovskiy noted that sleep consists of both NREM and REM stages and that the functional importance of their alternation remains unknown. 1038/s41593-026-02318-9.
