My son is just about to grow out of his 0-6 month sleep sack. I use the Halo sleepsack wearable blanket with optional swaddle (he only uses the swaddle around his belly). It's just a cloth wearable blanket. I noticed lately when I open it to change his diaper at about 5 a.m. that his legs feel cold. Is anyone using a fleece sleep sack for the winter? Would that be too hot? This is my third son but the first time I've ever used a sleep sack/wearable blanket. I'm about to order a new one on Amazon a size up, 6 months to 12 months, and I just would like some opinions before I buy. We keep our house at about 70 to 72 degrees.