Responses

In the novel it doesn't make her older just weak and tired the next day. But I think right now Aria doesn't care if it kills her or makes her die early in the long run because she only wants revenge and she'll do anything to get it even if it costs her life in the end. But she'll be more mindful of the hourglass later on
The fact that she keeps using the hourglass again and again even though she knows it makes her older bothers me. edit: On ch.32 she grew taller and she said it shortened her lifespan, technically making her older