by UNIVERSITY OF OXFORD
Sleep may not just be rest for the mind—it may be essential maintenance for the body’s power supply. A new study by University of Oxford researchers, published in Nature, reveals that the pressure to sleep arises from a build-up of electrical stress in the tiny energy generators inside brain cells.
The discovery offers a physical explanation for the biological drive to sleep and could reshape how scientists think about sleep, aging, and neurological disease.
Led by Professor Gero Miesenböck from the Department of Physiology, Anatomy and Genetics (DPAG), and Dr. Raffaele Sarnataro at Oxford’s Center for Neural Circuits and Behavior, the team found that sleep is triggered by the brain’s response to a subtle form of energy imbalance. The key lies in mitochondria—microscopic structures inside cells that use oxygen to convert food into energy.
When the mitochondria of certain sleep-regulating brain cells (studied in fruit flies) become overcharged, they start to leak electrons, producing potentially damaging byproducts known as reactive oxygen species. This leak appears to act as a warning signal that pushes the brain into sleep, restoring equilibrium before damage spreads more widely.
“You don’t want your mitochondria to leak too many electrons,” said Dr. Sarnataro. “When they do, they generate reactive molecules that damage cells.”
The researchers found that specialized neurons act like circuit breakers—measuring this mitochondrial electron leak and triggering sleep when a threshold is crossed. By manipulating the energy handling in these cells—either increasing or decreasing electron flow—the scientists could directly control how much the flies slept.
Even replacing electrons with energy from light (using proteins borrowed from microorganisms) had the same effect: more energy, more leak, more sleep.
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