We've never had a problem with chicks/juveniles with lights. We hatch all year also. They have a light all the time. When it's too cold to have them outside(like now), we just continue to have brooder bins full of chicks-but no mare than 15 per bin. I think if you over crowd them, they would tend to "beat" on each other. When they are about 2 months old-we put them outside.