In a national survey, almost half of contact lens wearers said they would like to be able to wear their contact lenses overnight. More than two-thirds said they would do so if their eye-doctor gave them the go-ahead. Many people have dozed off in their contact lenses, and having failed to suffer any drastic consequences, may be emboldened to do so more often. But is it safe to sleep in your contacts? The answer generally is no – not unless you are wearing lenses specifically approved for overnight wear and are wearing them to the schedule prescribed by your eye-doctor. The fact that you might get away with an occasional nap in your lenses by no means guarantees you will be able to sleep routinely in your lenses without consequences. The fundamental problem is that contact lenses restrict the flow of oxygen to the surface of your eye (the cornea), and the longer you wear the lenses, the longer the flow of oxygen is restricted. In extreme cases of over-wearing lenses, new veins grow out into the cornea as the body attempts to correct for the oxygen deficit.