The first story I will tell you about is about a radio. I woke up and took a quick shower, like I usually do on school mornings. I got out of the shower, and my sister ran up to me, really excited for some reason. "Jenna! Jenna! Guess what!" she said. I asked her what. "School is delayed! For 2 hours!" That was good news for me, because I was really tired that day. When I crawled back into bed, the radio was playing one of my favourite songs. I was half asleep, when my radio suddenly started blaring music, instead of playing softly. I snapped open my eyes, and as soon as they were open the music was back to normal. I heard Cameron mutter "sorry". Radio malfunction or mischievous ghost personally, I think it was Cameron.
The second story I'm going to tell you happened a little more recently. I was in bed, around 1:00 (and YES it was the weekend). I was just browsing the Internet on my iPod, my sister sound asleep. Then, she suddenly sat up in her bed and looked at me. Her eyes were a different colour than normal (it was dark, but bright enough to tell they were different). She looked at me and muttered something that sounded like, "My pants are blue." Her voice was different also. I looked at what she was wearing, and she had on blue silk pyjamas. I asked her to repeat it, because I didn't hear her. She said "The thingies... They're blue." I had no idea what she was talking about, so I asked her to say it again. She looked at me angrily and said "I'm not going to explain it again!" and fell back asleep.
I asked her about it in the morning and she said that she didn't wake up last night. At first I thought she was just sleep-talking, but how do you explain her being wide awake, her different eye colour, and her different voice? When I talked to her the next morning her voice and eyes were normal again. So, if anyone knows, please tell me!
And yes, your sister was just sleep talking. My sister and I have had entire nonsense conversations when one of us was sleep talking. Once I sat up in bed and stared at her; she thought I was awake so she jokingly threw a pillow at me. I caught it, mumbled, "Mum made this..." and lay down again. I was asleep the whole time! The pillow was actually a present we got Mum together one Mother's Day so in my sleeping state I connected it to her.
So sleep walkers/talkers are semi-aware of what's around them (so they can observe things like pillows or blue pants, and do things like unlock doors or open drawers) but they're not conscious, so even if their eyes are open they look "weird".