How many hours a day should you wear frequent replacement contact lenses?
To a certain extent, this depends on the characteristics of your eyes.
Your optician will be able to discuss with you what is best in your individual case, but as a general point, it's recommended that you wear your contact lenses for a maximum of 10-12 hours per day. Wearing your lenses for longer may cause your eyes to become uncomfortable, red and prone to infection.
If you have encounter any discomfort when wearing your lenses you should take them out as soon as possible, give them a thorough clean and replace them. If they continue feeling uncomfortable, take them out and visit your optician as soon as possible. While it might be nothing to worry about, it's best to have your eyes examined just in case.