Theory 17/Hours to Days/Circadian rhythms
Entrainment Is a Period Ratio
The claim
Circadian entrainment occurs over a limited range of the ratio between zeitgeber period and free-running period, so a weak cue can entrain if the periods are close.
01Mechanism
Phase shifts accumulate when the mismatch is small; beyond a range, the oscillator cannot follow and free-runs.
02Prediction
Entrainment should fail outside a ratio range.
03Refutation
Entrainment tracking cue strength alone would remove period matching.