The amount of light that your plants need varies from one plant to another. Some indoor plants call for direct sunlight while some call for indirect sunlight and do not need to sit in a window in direct light. Too much sunlight intensity will pale the leaves and eventually kill the plant while too little sunlight will stunt plant growth and cause the leave to wilt and yellow. Sunlight is the best source of light but you can use special lights (artificial lights) for plants that can be used in such situations. Plants also require some dark time (about 8 hours a day). Pale-leaf plants would mean that the plants need more light than dark-leaf plants.