Its pretty common. Most owners fail to control the light cycle and regulate hormones. I keep my flight cage covered and use uvb lights set on a 8 hour interval during the day. Then veggies are fed daily especially kale which seems to solve most egg issues with my hens.
You don't need to buy lights unless you're breeding. But for me, its very convenient. I don't have to remember to cover or uncover the cage at certain times of day. Just uncover when they're out, and cover after putting them away. Just use an el-cheapo plug timer, a brooding lamp, a featherbrite bulb, and you're good to go. Place the lamp over the cage and cover it. This is all optional, you can manually cover and uncover the cage as well.