Why my plant is dying

Its been quite worrying in the last few days to notice that my plant isn't actually doing as well as it did. The number of dying leaves has increased, while my number of new shoots has been slowly decreasing and there has been no flowers. I have represented my data in the following graph:

As can be seen, from April 4, the dying leaves has very ,much increased, with almost no new shoots. I was thinking about possible reasons for this, and today's lecture on aquariums helped me to come up with a possible explanation.

The section dealing with aquarium lighting explains that a specific type of light is needed for successful plant growth. These types of light replicate the natural environment.

The light in my room does not do this. It probably did not affect the plant as much previously, because normally I keep the curtains open and only switch the light on at night. But since we have had the cold weather the past week, I have had my curtains closed and the light switched on much more.

This had the effect of decreasing the amount of natural light the plant gets per day. So for my plant, this past week had longer nights and much shorter days. Which might explain why its seemingly "dying".

Therefore, I am trying to  to reduce the time that the light is on during the day, so that the plant has the optimal amount of light needed. Hopefully this will restore my plant.