Biological Rhythm in Phyllanthus, CUBE Causeri-cum-Chatshaala, Day-2, Somaiya College

How do we know what is the time period the Phyllanthus is inactive?
The experiment was discussed with Phyllanthus when is the phyllanthus opening and closing the leaves? The graph was drawn with time against leaf opening. Where it was seen that at 6am the leaf opens and at 6pm leaf closes. This cycle keeps on repeating, hence there is 24hrs period between two active peaks.

The graph showed that on second day there is some delay in the opening time and also closing time.
Similarly, on third day there is delay in opening and closing time. But the in all the cases we saw the time period between two peaks is 24hrs.

The question came how do we know that this pattern will not change if we change light patterns?
Is this pattern internal or dependent on external light?

It was discussed to keep phyllanthus in constant dark and then put light for 12hrs and dark for 12hrs. The light will be exposed when there is night and dark will be kept there is day time. This will invert the normal day light exposure and help us to know if the biological rhythm is based on internal clock?