Sleeping at night

Hi,
i have a chicken tractor setup with 6 pullets. im new to raising chickens but have done lots of reading but havent found the answer i was looking for quite yet. my coop has 2 roosts for the girls to sleep at night that are about 4 feet long and each one has a ramp about 4 feet long leading up to it.i picked up my pullets saturday, the first night all 6 were attempting to sleep on the ground so once they were docile at night i picked them up and put them all in the coop. then i went around to the doors for the coop and picked them up one at a time and moved them onto the roosts. sunday night i checked on them and all 5 were inside the coop, 2 on the roosts and 4 on the floor, one more or less in the doorway. once again i moved all the ladies to the roosts and went back inside, monday night exact same thing, 4 on the floor. moved into the roosts again. tuesday i tried moving the roosts a few inches farther from the wall giving more space thinking that maybe they were too close, and moved the ramp a few inches too. but when it was night time, same thing 4 on the floor and 2 on the roosts. they dont seem to head inside until its fairly close to being dark. and i wonder if maybe the lighting is too bad and they cant find their way into the roosts so they just plop down on the floor. now where i live im in the city and there are no racoons and no coyotes or anything so its not that im worried about predators. i just want them to get used to the roosts because thats what ive read up on that they should be doing. i have thought about trying to add in a window for light, but i dont know if it will help much if its still dark outside. my other thought was to get one of those solar garden ligths from home depot, theyre pretty low light, like 1.2 lumens, but they run for a few hours. i worry that it might stay on too late and they might not want to sleep properly, but then when i think of how little light it really is, that maybe it will be fine. my thought was to buy 1 single of those solar garden lights strip it down to take it apart, put the mini solar panel on the roof and wire in the small led light into the ceiling of the coop, with it loosing its reflective surfaces that the light normally has, i imagine the useful amount of light will severely diminish. which in my case is probably a good thing. my goal is to give them just enough light to navigate the coop once it gets dark, but without throwing off their sleep cycles. the reviews online i read for some of the lights are reaally crappy (for landscaping, stating theyre barely enough to see and they only last 2-3 hours) but for me i thought that might be a good way to go. any opinions would be much appreciated.

 

believe when i got them on saturday they said they were 18 weeks. the guy at the egg ranch i bought them from said they were just starting to lay or were going to be a week or so from it, but they had a lot and they were all the same age give or take a week. but they didnt have an exact date they were born on that i was informed of. so i guess anywhere from 18-19 weeks.