To a certain extent, this will depend on the characteristics of your eyes and your optician will be able to discuss with you what would be best in your individual case.  As a general points, it is recommended that you wear your contact lenses for a maximum of 10 to 12 hours a day. Wearing your lenses for longer may cause your eyes to become uncomfortable, red and prone to infection.Should you experience any discomfort when wearing your lenses you should take them out as soon as possible, give them a thorough clean and then replace them. If they continue to give discomfort take them out straight away and visit your optician as soon as possible. While the discomfort may not be something to be concerned about it is best to have your eyes examined just in case.