In addition to making people plumb tuckered out, sleep deprivation can selectively dismantle a brain circuit responsible for social recognition.
In a new study of mice, researchers at the National University of Singapore found that five hours of sleep loss made it harder for the animals to distinguish mice they’d already encountered from strangers. Caffeine appeared to reverse that effect.
Published in the July 2026 issue of Neuropsychopharmacology, the study focused on a small but functionally distinct zone in the hippocampus, the brain region central to memory and learning, called CA2.
In addition to handling social memory — which is the ability to recognize familiar individuals and distinguish them from strangers — the CA2 also receives signals tied to the regulation of sleep and wakefulness.
For the study, researchers induced five hours of sleep deprivation in male mice using gentle handling, then measured two things: the brain’s ability to strengthen connections between neurons in the CA2 region, and the mice’s ability to distinguish a familiar mouse from a stranger.
Sleep deprivation disrupted both. At the neural level, it impaired long-term potentiation (LTP), the process by which connections between neurons strengthen during learning. At the behavioral level, sleep-deprived mice failed to distinguish novel from familiar individuals, a deficit not seen in the rested control mice.
“Sleep deprivation does not just make you tired. It selectively disrupts important memory circuits,” Dr. Lik-Wei Wong, first author, said in the NUS Medicine press release. “We found that caffeine can reverse these disruptions at both the molecular and behavioural levels. Its ability to do so suggests that caffeine’s benefits may extend beyond simply helping us stay awake.”
The authors said the study underscores the fundamental role of sleep in supporting healthy cognition and memory, while suggesting employing caffeine may help them better understand how to reduce some of the memory problems tied to sleep loss.
“By demonstrating that caffeine can restore selective neural pathways impaired by sleep deprivation, the study strengthens insights into potential targeted molecular therapies for cognitive conditions,” the university said in an announcement of the publication.
The researchers said they plan to build on the findings by further examining the effect of caffeine on memory consolidation and retrieval.
This study contributes to a sometimes contradictory body of evidence on caffeine, sleep and cognitive performance. DCN covered a 2021 Michigan State University study finding that while caffeine helped sleep-deprived people with simple alertness tasks, it offered no benefit for more complex “placekeeping” tasks.
A 2024 German-Swiss study found that repeated caffeine intake during chronic sleep deprivation may suppress some gray matter responses, potentially worsening the brain effects of sleep loss.
More recently, a 2025 University of Montreal study found that caffeine taken before sleep makes the sleeping brain more active and less restful, disrupting normal neural recovery patterns.
The new study was authored by Lik-Wei Wong, Mohammad Zaki Bin Ibrahim, Aiswaria Lekshmi Kannan and Sreedharan Sajikumar. Funding came from the NUHS Seed Fund, the Singapore Ministry of Health and a National University of Singapore Research Scholarship. The authors declared no competing interests.
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