It’s not typically recommended that you sleep in your red contact lens, but it can also depend on the exact style, type and quality of the contacts. Since colored contact lenses can either be opaque or theatrical it can depend on which red contacts you purchase.
The contacts that you would purchase for vision correction, and every day use, will typically be okay to sleep in occasionally, as opposed to the contacts such as red angelic, vampire red and evil red contacts that will be more for costume parties.
The reason is that the red contacts for every day use, are usually better quality meant for longer periods of wearing them. You should always check with your eye care specialist to find out exactly how long you can wear them, and whather or not sleeping them is dangerous.
You should always keep them clean and protected when not using them. Even though you might only be wearing your bright red contacts one night at a time, you still need to treat them with care because one day you’ll be putting them back in your eye, and if they are torn, ripped or damaged in any way you risk causing damage to your eye which can be very serious.
You should keep in mind that while you might find some fun red contact lenses to enhance your outfit, it’s still going into your eye and should be treated with respect and following the rules is a must.