One way to determine if an indoor plant needs more or less sunlight is to observe its leaves. If the leaves are pale or yellow, it may be an indication that the plant is receiving too little light. On the other hand, if the leaves are scorched or brown, it may be getting too much direct sunlight. Checking the specific light requirements of the plant can also be helpful, as different species have different needs. In general, it's best to place plants near a bright window with filtered light or use artificial lighting if natural light is not available.