They could be having a deficiency. Are the leaves turning a particular color (besides yellow) prior to falling off? Even if it's just yellow, the fade pattern can also tell you if it's nitrogen, calcium, or magnesium.
Throw up a picture if you'd like. Besides the sun, which is clearly important, it could actually be a different issue. I've grown hundreds of plants that have never recieved sun light.
The weird thing is they’re not even turning yellow. They’re just shriveling up and falling off. Maybe not enough water? I am sometimes bad about that
But I’ve been better lately.
I have added coffee grounds twice and I’ve read they like that and that it would stimulate leaf growth, which it did. But maybe they need a more all encompassing fertilizer or compost or something???