Sleeping in contact lenses, advertised by some lens manufacturers and certainly, very convenient, has been shown by a recent study to increase the chance of eye infections by 10 times. While sleep-in, or extended wear lenses, do transmit more oxygen than earlier lenses and are OK for an hour long nap, overnight sleeping in them can result in severe eye infections and eye inflammation, which may cause an inability to wear lenses further. It is simply not worth the risk.