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July 13, 2025 54 mins

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The genetics of sleep duration and sleep timing.

Episode Summary: Dr. Ying-Hui Fu discusses her research on the genetics of sleep, focusing on natural short sleepers who thrive on 4-6 hours of sleep and the heritability of sleep traits like duration and timing. She explores how sleep efficiency, rather than just duration, may explain why some need less sleep without health deficits, and delves into the molecular and circadian mechanisms regulating sleep. 

About the guest: Ying-Hui Fu, PhD is a neuroscientist and professor at UCSF, where her lab studies the genetics of human sleep behaviors, particularly sleep duration and schedule.

Discussion Points:

  • Sleep Traits Are Genetic: Sleep duration (how long you sleep) and sleep schedule (when you sleep) are partially heritable, with most people needing 7-9 hours, while rare natural short sleepers thrive on 4-6 hours.
  • Natural Short Sleepers: These individuals fall asleep quickly, have high sleep efficiency, and live healthy, active lives without deficits, possibly due to faster toxin clearance and repair during sleep.
  • Sleep Efficiency Matters: Short sleepers may complete restorative sleep processes (e.g., clearing toxins, repairing damage) more efficiently, allowing them to need less sleep.
  • Circadian & Entrainment Pathways: Sleep timing is regulated by a molecular clock and environmental cues like light, with mutations in entrainment pathways causing extreme schedules (e.g., early bedtime or night owl tendencies).
  • Modern Lifestyle Harms Sleep: Stimuli like blue light and tense media disrupt sleep patterns, leading to widespread sleep deprivation and health risks.
  • Shift Work Risks: Shift workers face higher risks of diseases like cancer and neurodegeneration due to disrupted sleep cycles, though genetic background influences susceptibility.
  • Finding Your Sleep Rhythm: A two-week vacation without stimulants or artificial light can help determine your natural sleep schedule and duration.
  • Sleep’s Health Impact: Poor sleep is a major factor in aging and diseases like Alzheimer’s, making it as critical as diet and exercise for health.

Related episode:

  • M&M 237: Circadian Biology: Genetics, Behavior, Metabolism, Light, Oxygen

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