Smologies with Alie Ward CIRCADIAN RHYTHMS with Katherine Hatcher
Mar 6, 2026
Katherine Hatcher, a chronobiologist who studies hormones and sleep cycles, explains circadian rhythms and the brain’s tiny timekeeper. They cover daylight saving time’s harms, how light and temperature cue our clocks, chronotypes like owls and larks, and why many body clocks—not just one—shape health and daily life.
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There Are Many Circadian Rhythms
- Circadian rhythms are many separate ~24-hour biological patterns, not one single thing.
- Katherine Hatcher explains 'circadian' means about a day and highlights rhythms across sleep, digestion, hormones, and more.
Cooler Bedrooms Improve Sleep
- Try sleeping in a slightly cooler room because body temperature naturally drops at night to support sleep.
- Katherine Hatcher notes cooler nighttime temperatures align with evolved sleep physiology for better rest.
Rhythms Evolved To Optimize Survival
- Circadian rhythms evolved to align behavior and physiology with the 24-hour light-dark cycle to optimize survival and reproduction.
- Disruption of these evolved patterns correlates with negative health outcomes via hormonal and molecular pathways.