Yes I used hot water bottles last night and tonight for the kids and they were delighted. Happy memories of my childhood brought back as well. Put fleecy blankets under the sheets and then wrapped the kids pj's in the hot water bottles in their beds (two for each and rotated them from youngest to oldest). Pj's nice and hot when they came out of bath and then they slipped into their cosy beds. I don't leave the water bottles in their beds though so they were all transferred over to ours so must go and enjoy!