The efficient light spectrum for the plant is mainly in the Red and Blue wave length between 450-700 Nanometers (see diagram below). The light from normal house bulbs has smaller portions of this spectrum and rather larger portions from spectrums not efficient to the plants. Also the Light intensity is not strong enough and the intensity is diming in a geometrical column as you get farther from the bulb. So if you want the plant to feel some light you must lift the plant until it is annexed to the bulb. In normal conditions the plants cannot feel the light from the bulb because by the time it reaches them it’s intensity is too weak.