Why do lights blink when it appears?

Question

Might contain spoilers!

In the TV series Stranger Things, more particularly in S01 E08, in Will's house when the Demogorgon appears, just before that the lights blink, like an indication of it's arrival. Also Jonathan is shown telling Nancy the same thing -

Nancy: Did you hear that?

Jonathan: Don't worry. It's just the wind. My mom, she said the lights speak when it comes.

The blinking of lights has also happened earlier. What is the theory behind the lights blinking when it comes?

Answer 1

There is no official answer but from my understanding:

Anyone or thing in the Upside-Down gives off an electromagnetic pulse, that when this thing or person is close to you, it affects the eletronics in the real world.

That is why when Will is in his little castle:

It is close to his house, that's why the lights flicker, the same thing happens with the demogorgon.