I heard that its not good to wear panties every night to bed? Is that true?

Why not? That doesn't make sense. Why not? It's your choice. Certain fabrics may cause irritation but you would know that already.
Maybe. If the underwear is cotton and absorptive than there usually is not a problem wearing them every night to bed, however, this is one of those times that one can allow the vulva to "free breathe" by wearing nothing and helps to maintain good vulvar health.