Maybe she's a hot sleeper. My DD is this way. In fact, she just recently started wearing nightgowns again, but for 2-3 years she refused to wear any clothes at all - she insisted on sleeping nekkid because she was hot, even during the winter with the heater vents closed in her room and a thin blanket. Lordy, I can just imagine having to explain that if, God forbid, anything happened - she was last seen going to bed naked. Talk about looking BAD. We opted to not make a big deal out of it, and when the time was right she came around and went back to sleeping in pj's again