Sleep helps the brain enter repair mode to clean up free radicals, Chinese study finds
Findings open avenues for therapies to combat sleep disorders, which particularly affect older people and increase disease risk
Sleep serves as the brain’s nightly clean-up crew, flushing out harmful oxygen-derived free radicals that accumulate during wakefulness, Chinese scientists have discovered in a landmark study.
The research published in Cell Metabolism on May 15 deciphers how hydrogen peroxide (H₂O₂), a reactive by-product of metabolism, acts as a molecular signal to trigger sleep and restore balance in the brain.
By confirming a decades-old hypothesis, the team found that when H₂O₂ levels rise in sleep-regulating neurons, the brain switches to “repair mode”, prompting restorative slumber.
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This research not only solves a long-standing mystery of why sleep is biologically essential but also opens pathways for therapies targeting oxidative stress to combat sleep disorders.
While scientists around the globe have identified some molecular changes that occur in the brain during sleep, Liu Danqian, a researcher from the Shanghai-based Centre for Excellence in Brain Science and Intelligence Technology, an affiliate of the Chinese Academy of Sciences, who led the study, said this was “the first time” they had fully delineated how a molecule specifically functioned in the brain.
The regulation of sleep is a type of instinctive behaviour known in neuroscience as “homeostatic regulation” – the body’s ability to maintain a stable internal environment.
Liu said scientists had been exploring the kinds of material changes in the brain that trigger homeostatic regulation of sleep.