Theory 05/Thresholds & Tipping/Sleep onset
Sleep Onset Is a Crossover
The claim
Sleep onset occurs when homeostatic pressure crosses the circadian wake signal, so the same sleep debt can leave a person alert at one hour and asleep at another.
01Mechanism
Two processes oppose each other across the day; sleep begins at their crossover, which is a timing point rather than a debt threshold.
02Prediction
Onset time should follow the crossover rather than accumulated wakefulness.
03Refutation
Onset tracking sleep debt alone would remove the circadian term.