Light in the room turned on by itself after grandfather's funeral

Alright, I'll come out of read-only and bump this with my story. What's notable is that the witness of the paranormal in this story wasn't just me, being a 6-7 year old kid, but also my parents.

Anyway, at the age of 6-7 (I don't remember exactly, because at that time I was still in kindergarten, and only went to school at 7) my grandfather died. As far as I remember, he was, as they'd say now, a skuf: loved beer, the banya, and the TV show "Play, Accordion". Well, what do you expect from a former Soviet militsiya officer? So anyway: I was the youngest and most beloved grandson of grandpa-doead. My older brother told me about his death, picking me up from kindergarten. I, being a kid, didn't really take it seriously until the funeral. Like, shit happens. But at the funeral, seeing the coffin with the body, I started crying and all that. My mother tried to calm me down in every way - gave me valerian and such, so the kid's head wouldn't completely blow from hysteria and stress. In the end, after the funeral and the memorial meal, the whole family, exhausted, came home in the evening and went to sleep. I slept in the farthest room of the apartment, right opposite my parents' bedroom. A little corridor of 5-7 meters separated it from my room. The bed was right to the right of the entrance, and to the left of the entrance was a wall with a light switch. According to Soviet standards, it was high - I couldn't reach it without a chair. Now I'll explain why I'm describing the layout in such detail.

I fell asleep without problems in the evening on the bed, because I was probably more exhausted than anyone from constant crying. But in the middle of the night I suddenly woke up because someone in my room turned on the light. I grumbled displeasedly, without opening my eyes. The light went off after a couple of seconds. I was almost asleep again - the light turned on again. I grumbled again - the light went off again and after some time turned back on. Then I turned on the bed, since I was lying on my stomach and couldn't see who had entered the room. I turned - and there was no one in the room. Then I decided that my brother was messing with me - went out into the little corridor, but it was empty too. Went into my brother's room, which was to the right of my room and my parents' bedroom, a bit further away (the corridor was T-shaped): doors closed, I could hear sleepy snoring. That's when I got scared. I returned to the room, decided not to turn off the light and sleep like that. Just lay down on the bed - the door to my parents' bedroom opened. My mother and father come in to me. I immediately pretended to be asleep, so as not to risk getting smacked. But instead of coming into the room, my parents started poking the light switch and whispering. From their dialogue I understood that my mother couldn't sleep after the funeral and she saw all the shit with the light through the gap under the door. So she woke up my father and they went to find out why I was playing with the light in the middle of the night. And in the room I'm sleeping (supposedly), there are no chairs by the switch, but the light, damn it, is on. They stood for a while, poked at this fucking switch, looked around the room again and went back to their bedroom. And I couldn't fall asleep for a long time in the dark, it was scary. The switch was, by the way, like the one in the pic related.