Fittonias do better in increased humidity. Unfortunately, misting does not effectively increase humidity unless you are misting hourly 24 hours per day. Humidifiers work best and pebble trays are more effective than misting. Many folks use Fittonias in terrariums where humidity is maintained in the enclosed space.
It is possible to grow Fittonias without artificially increasing the humidity, but it requires very close attention to the soil moisture. This is a plant that does not tolerate dry soil, high temps or direct sun. The lower the humidity, the less the margin for error.