Behavioral Grooves Podcast Why Does Jet Lag Hit so Hard? | Daniel Forger
Feb 23, 2026
Daniel Forger, a mathematician and circadian rhythm researcher at the University of Michigan and author of Biological Rhythms, explains why jet lag hits so hard. He discusses what biological rhythms are and how wearables capture noisy signals. He explores sleep timing versus duration, adapting to new day lengths, and connections between circadian timing and mood.
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Billions Of Clocks Drive Daily Experience
- Biological rhythms span from cellular clocks to whole-body behaviors and shape mood, performance, metabolism and sleep.
- Daniel Forger emphasizes we have billions of clocks and their coordination explains daily changes in focus, energy, and mood.
Treat Wearable Scores As Probabilities
- Use wearables as probabilistic tools and demand uncertainty estimates, not single definitive scores.
- Forger recommends devices report error margins and suggests Kalman-filter style algorithms to combine noisy heart-rate and activity data into better estimates.
Don't Delay Buying A Wearable For Insights
- Buy a wearable now if you want long-term insights; technology is improving but early use helps build personal baselines.
- Forger says major devices are okay and future integration with clinicians will boost precision medicine.
