For us it was mostly the our dogs' choice if they wanted to or not. One of them loved sleeping in the bed with us and another one preferred to sleep in her own bed. The one who liked her own bed was rather larger and had a thicker coat so I think she found sleeping in a bed with others just too warm probably. We had one other dog who used to sleep in the bed with us too. When he was alive, the larger one would also come to bed with us. After he died, she stopped doing that. We think she only came to our bed because of the other dog. The smaller one has a much thinner coat and really loved being extra warm so she always slept in our bed even if we were not there. She always went under the blankets and sometimes it was hard to know where she was! The only times she ever slept outside the bed would be when she was waiting next to the kitchen for food or if she went to sleep next to a heater. When she was in bed, she sometimes went to sleep on my head for some reason. I think she liked to be on the pillows.