I honestly think "Aart's" comment was spot on. Chickens do the strangest of things, while we wring our hands and fret, trying to figure out what is best for them ... moving roosts, having lighting - soft or otherwise etc.
I have 3 chickens only now. One ( my Aussie Araucana ) lives separately from the others ( for her safety ) and has her favourite roost - which happens to be a brick on it's highest side up, with a soft cloth covering it !!! on top of a nesting box .... and she roosts there absolutely every night. That happened somewhat by accident !! My other two, debate the sleeping issue every other evening. If it is cold, they snuggle together in a nesting box - which incidentally, they have NEVER used to lay eggs in. Straw goes into those frequently, and within 10 minutes they have kicked the whole lot out ??? ( these are my RIR and Welsummer ). The Welsummer ( Mandy ) ... occasionally roosts higher up on a roosting rail - but never for the whole night that I have observed. She enjoys the company of her friend Molly RIR who absolutely never roosts, and Mandy Welsummer most often sleeps in a nesting box ( which as I said is never used for laying ) .... Molly mostly sleeps in the their own preferred choice of laying nest - which is straw on the bottom of the coop. That is right in front of Mandy - so there are two levels of chickens when I check them. One in the floor nesting straw, and one in the 'supposed' nesting box just above. They both lay eggs in the straw on the bottom of the coop.
They are absolutely happy this way. They lay beautifully, although Mandy has knocked off laying at the moment as she is growing new feathers after a seriously loooong moult. I get 2 eggs a day from 3 chickens ( 3 a day when Mandy is on the job ). The weather here is ridiculous ( Victoria, Australia ) .... and we are supposed to be in Spring, but we have heaters on in the house - it is as cold as the depths of winter. Which of course, has upset the chickens no doubt, somewhat.
I keep them shut up for the most part, when it rains all day and night, as it has this past 2 days. They are allowed out for a wander around in the mud, and I figure as we are coming into Summer - which WILL happen with a vengeance --- they will have plenty of time to free range and use their runs. A few days of being 'caged' won't hurt them - although they do complain loudly.
I honestly wouldn't worry too much about where chickens put themselves to bed, much as Aarts said. I have only had chickens for 18 months or so, but have discovered heaps about them - particularly from the BYC site ( which is fantastic ) .... and from my own observations of their quirky behaviour.
They all are, none-the-less adorable. I lost my other 2 chickens - a Silkie to upper resp. failure due to being saturated in a storm, and I was unable to get to her during that time to keep her dry and save her ... and the other, a Barnevelder - a beautiful chicken, but she succumbed to some disease or other - suggested here on BYC several times, as possibly Mareks' disease - which wouldn't surprise me, considering what I have learned about their health issues.
So - don't worry too much, chickens will sort themselves out THEIR way ... and ultimately, not ours. Although keeping a close eye on them several times daily to make sure they are behaving normally, and not showing any potential nasties, is essential.
Good luck with it all.
Cheers .... AB