I have 3 hens, close to laying age(barred Holland, buckeye, and black australorp). I was just given the bird about a week ago. I'm having trouble getting the birds to sleep on their roost. The Holland and australorp want to sleep on the window and the buckeye sleeps on the floor of the coop. Last week I went out 3 nights and put them all on the roost. A cold front moved in over the weekend so I blocked the window to keep them from roosting and getting sick from cool night breeze. I also added a light to the coop, its a small coleman lantern about 8 inches tall it runs on 4 AA batteries and runs from 5pm until the batteries die, usually around midnight. It hangs under the poop tray. Now all the birds sleep on the floor of the coop. Last night I tried putting a few treats on the roost to try and entice them up but I don't think they ever found them. I live in south Arkansas to give an idea of weather, at night the temperature ranges from mid 30s to high 50s.The birds act fine, look great, and eat good, should I be worried about them sleeping on the floor? Is it necessary for them to sleep on roost? I am new to chickens so any advice would be helpful. Thanks.