You might see if very lightweight sheets help her comfort. You mentioned that adjusting the room temperature left her feeling unprotected, and it reminded me of when I lived in Palm Springs. The temperature was over 100 degrees even at night - so sleeping with any sort of blanket was out of the question. I absolutely could not sleep without anything to cover me though. I used a thin sheet, and it took some getting used to, but it did end up working well for me after about a week. I didn't even need it to cover my entire body to make me feel comforted - I just needed it across my shoulders mainly (I think these preferences would vary greatly depending on the person). You might try using a heated blanket beneath her (I've seen some that are designed to be placed underneath the body, and only get very moderately warm, so there's no chance of burning) to keep her warm, and see if a think sheet is enough to help her feel protected.