How did I wake up without my panties on?

Few years ago, once at a summer season, after taking a shower I went to sleep and fall asleep wearing a skirt and T-shirt and when I woke up around 2 am, I went to take water from the fridge then I realized I was not wearing any panties underneath...I looked for my panties, but I did not find anywhere near my bed.

I usually used to remove my bra during the sleep if I would feel Hot in summer seasons but never removed my panties by myself.

I wonder, How I woke up without my panties?

I had My mom-dad and one of my sister at home and my sister used to share my room with me.

Sayana · 22-25, FNew

@Quimliqer I was tried at that night, I went to take a shower, and I think I was wearing them as it was only 9 pm and my sister was still waking up.

JamesBugman

Obviously someone came into your room and managed to get them off without you waking up. It can be a fun game to play.
Do you sleep with an open window?

Sayana · 22-25, FNew

@JamesBugman I sleep with open window but it's not a usual thing, I mean someone come and remove my panties off at midnight...i