The Microbiota-Sleep Connection — Implications for shift workers
Joe Alcock MD
University of New Mexico, Department of Emergency Medicine
Did you know that the bacteria and microorganisms in our bodies are just as numerous—if not greater—than our own human cells? Or that modern, industrialized people sleep less than our ancestors? These are familiar facts, but the real question is: how do they connect?
Dr. Joe Alcock, an emergency medicine physician and researcher at the University of New Mexico, visited Notre Dame to explain how our microbiome and circadian rhythms are intertwined, and its associations with various health consequences.
These are some key takeaways:
1. Gut Microbiome and Human Health
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Our microbes equal or outnumber human cells and carry 100 times more genes.
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The gut microbiome has its own circadian rhythm, regulating digestion, immunity, and metabolism.
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Sleep and eating disruptions interfere with microbial cycles.
2. Sleep and Circadian Rhythms
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People today sleep 5–7 hours on average, less than pre-industrial humans.
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Compared to other primates, humans sleep less, on average. However, REM sleep makes up a greater share in humans than in other primates.
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Sleep supports immunity, metabolism, and microbial stability.
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Maybe we aren’t sleep deprived? Current hunter-gatherer communities sleep, on average, 5-7 hours (less than CDC recommended) and are healthy.
3. Consequences of Sleep Disruption
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Night shifts and late nights are linked to:
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Metabolic issues, weight gain, and pre-diabetes.
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Higher risks of breast and prostate cancer.
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Reduced sleep efficiency and chronic sleep deprivation.
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How does shift work impact microbial oscillations?
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Day-shift workers show strong microbial rhythms.
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Night-shift workers show weakened rhythms.
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Germ-free mice study suggest that disrupted microbial cycles promote weight gain.
4. Evolutionary Perspective – Gene–Environment Mismatch
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Humans evolved under natural light-dark cycles; artificial light and irregular schedules cause a mismatch between genes and environment.
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Group safety once influenced sleep architecture; difficulty sleeping in new places (“first night effect”)
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Falling asleep instantly may indicate sleep deprivation, not health.
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Eating at night worsens circadian misalignment; microbes may even drive food cravings via satiety hormones.
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GLP1 drugs (i.e Ozempic) have an interesting association with sleep apnea, sleep quality.