How Body Size, Metabolism and Sleep Relate

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The biological roots of sleep are tied to mitochondrial metabolism.

Episode Summary: Dr. Gero Miesenböck discusses the evolutionary and metabolic basis of sleep, exploring how mitochondrial energy production in neurons, particularly in fruit flies, drives the need for sleep to manage harmful byproducts like reactive oxygen species and lipid peroxides. They discuss how sleep-inducing neurons sense these byproducts, the role of mitochondrial dynamics, and the broader implications for why all animals, from jellyfish to humans, require sleep. The conversation also touches on how body size and metabolism influence sleep needs across species.

About the guest: Gero Miesenböck, MD is a professor of physiology at the University of Oxford, renowned for his pioneering work in optogenetics and his research on the neurobiology of sleep using fruit flies and mice.

Discussion Points:

• Sleep is universal across animals, even in jellyfish without centralized brains, suggesting a fundamental metabolic purpose tied to mitochondrial energy production.
• Mitochondria produce energy efficiently using oxygen but generate reactive oxygen species that can damage cells through lipid peroxidation, necessitating sleep to repair this damage.
• Sleep-inducing neurons in fruit flies contain sensors that track lipid peroxidation products, acting like a digital memory to signal when sleep is needed.
• Smaller animals with faster metabolisms, like mice, require more sleep and have shorter lifespans due to higher oxygen consumption and oxidative stress.
• Mitochondrial diseases in humans often cause intense tiredness, likely due to increased electron leaks in the mitochondrial energy production process.
• The evolutionary origin of sleep likely stems from the oxygen revolution 2.5 billion years ago, enabling complex life but requiring mechanisms like sleep to manage metabolic side effects.
• Caloric restriction reduces sleep need by lowering the production of harmful metabolic byproducts, supporting the link between metabolism and sleep.

Reference paper:

• Study: Mitochondrial origins of the pressure to sleep

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*Not medical advice.

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