Yeah...that's awesome. Well, I know it works overtime based on conditioning. Those who have conditioned themselves to the normal rhythm can easily adapt. But those who have a disrupted rhythm either from altered sleep pattern due to illnesses or occupation like long distance drivers, night club attendants etc. Those ones are already conditioned to stay awake in the night and sleep in the afternoon no matter how bright the sun shines.
RE: The Mechanism of circadian rhythm - Explaining Why You Feel Drowsy at Night