Jains avoid eating after dark mainly because of ahimsa — the principle of non-violence.

Even if electric lights exist, the traditional concern remains:

• Small insects and जीवों (living beings) may be attracted to food, water, or light and get harmed.
• In darkness, it is harder to see and protect tiny life forms.
• Eating only during daylight supports carefulness, restraint, and mindfulness in daily conduct.
• The practice is also linked to digestive discipline and a simple, regulated lifestyle.

So the rule is not only about visibility. It is about maintaining maximum care to avoid injury to living beings, which is central in Jain Dharma.