What is the reason for my eye redness when i wear my contact lens too late at night?

Many possibilities: Poor fit, dryness, irritation from preservatives in your cleaning solution, buildup of protein deposits on the lens itself are all common possibilities. Although some contacts are approved for long-term/overnight wear, i believe the healthiest options are to never wear overnight, and consider daily disposable lenses (so that you are always putting in a clean, fresh, preserve.-free lens each day).