Couldn't Sleep (spoilers)

I kept thinking about this film. Any film that stays with your after watching is considered a good film in my book.

I couldnt figure it out. At first I figured that the 7 sisters died the way they did and then were haunting the 3 sisters after they summoned them. But I then came to the conclusion that possibly the light at the bottom of the lake is its own entity and it captured the 7 sisters one by one one after another. But why? and how many others? and why the mother?


Another thing is maybe the light selects its prey...it gave the scarf to isa, but she chose to throw it back into the lake after the fight with Josh and then June found it and the light took her instead.
I remember Isa saying it was having a hypnotic pull type of effect or something similar.... Did the mother also find the scarf? did the 7 sisters? did it belong to the 7 sisters.

Also does the light take skinny dippers and party people who swim after midnight...?

I am not sure, but June admits to the birds and making the time lapse video. Is this true or is she just saying it. Cause at the end she finds another bird and her other sisters have already left and she's alone. If she did it she would have to go find diff types of birds, kill it and bring it back and place it there. Also something moves the camera on her last 2 Swims.

My theory has many holes. What do you think? I will watch it again.
Its hard to focus on a theory. Is it the 7 sisters? is it the mothers theory of reincarnation. is it a combination of both. Is the light good or bad?