Do you have a bully chicken, or are your nesting box hens not being allowed on the roost? My chickens have similar behavior. For mine, this is space issue and also has to do with their group dynamic. The two roosting bars are parallel and too close to coup floor. It was a poor design. The nesting boxes are to the side, and the tops of them are higher than the roosting bars. Out of the four girls, we have a boss, her enforcer, and two subordinates. They are very bonded and don't really bully each other too much except when Daisy, the chicken with the lowest rank, is too presumptuous. They clearly care about her though as I posted here: 
https://www.backyardchickens.com/th...r-unhappy-cold-chicken.1216749/#post-19428150. The boss always sleeps on top of the nesting box with her enforcer across from her. The other two either roost or sleep in the nesting boxes under the other chickens. I feel like they may rotate to share the warmth. In summer they all sleep on the roof, and rotate who is on the far end, except the boss who is always in front.