Why do I keep waking up to my little sister crying in the middle of the night? Is something wrong with her or me?

I (26M) live with my parents (60s) and my little sister (9F). My sister's room is next to mine, and my room is next to my parent's bedroom, so basically my sister's room is directly next to mine. I sleep on the left side of the bed, and my parents sleep on the right side. It's pretty normal to wake up when my parents move around in bed or when my roommate stirs, but the past couple of years, I've been waking up in the middle of the night (1am to 3am) to my sister's cries, and I'm not just talking about whimpers. It's loud, desperate cries that sound like she's terrified or in pain. When I tell my parents, they just brush it off and tell me that she's "just being a kid."<br><br>The thing is, I'm not sure if there's something wrong with my sister or me. She's never been the quietest kid, and she's had some behavioral issues in the past, but my parents have always brushed it off and said she's just "being a kid." They've also been pretty dismissive of me about this whole thing.<br><br>I've tried to talk to her, but she just says she's scared and that she has nightmares, but she's never told me what they're about. I've tried to tell my parents about this, but they just say it's normal and she'll grow out of it. I've even tried to sleep with earplugs, but they just don't block out the sound of her crying completely.<br><br>I'm not sure if this is something serious or if it's just my paranoia, but I'm worried about my sister and myself. I feel like I'm losing sleep and my sanity over this. I've even considered sleeping in a different room or even moving out because I feel like I can't get any sleep anymore.<br><br>So, what do you guys think? Is something wrong with my sister or me, and what should I do about it?