Sleeping with your makeup on clogs pores which then causes breakouts, can dry out the skin and cause redness of the skin as well as sensitivity. Sleeping in makeup also speeds up the process of aging which can lead to premature wrinkles according to skin experts.
Makeup can indeed make you appear more beautiful, but if you leave it overnight or forget to remove it before bed too often, it can lead to a collagen breakdown, which can make you appear older and your skin can appear tired and unhealthy.
One night of sleeping with your makeup on is unlikely to cause harm to your skin, but doing this often will likely cause your pores to become clogged. This then results in the formation of a microcomedone, a condition which attracts the acne-causing bacteria to your pores.
The skin best renews itself while we sleep, and leaving makeup on overnight prevents skin regeneration.