Sigma Nutrition Radio #579: Is Your Chronotype Hard-Wired or Modifiable? And What Does It Mean for Health?
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Oct 7, 2025 Alan Flanagan, a researcher in nutrition and chronobiology, delves into the fascinating world of chronotypes – our biological sleep-wake preferences. He explains how these are distinct from simple lifestyle choices and discusses various measurement methods, from lab tests to questionnaires. The conversation explores genetic and environmental influences on chronotypes and their significant health implications, particularly concerning meal timing and metabolic health. Alan also addresses the challenges for late chronotypes in a society structured around early schedules.
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Chronotype Is A Biological Behavior
- Chronotype = behavioral expression of internal circadian timing, not just preference.
- It reflects biology (internal clock) shown by self-selected sleep-wake timing when unconstrained.
Prefer DLMO In Lab; Use MCTQ In Field
- Use dim light melatonin onset (DLMO) as the lab gold standard when possible.
- Use the Munich Chronotype Questionnaire (MCTQ) for validated, practical field assessment.
Correct For Sleep Debt To Find True Phase
- MCTQ calculates midpoint of sleep and corrects for sleep debt to estimate true circadian phase.
- Correcting for weekday sleep debt is crucial because people typically alter wake time, not bedtime.