These are your classic light bulbs used in the home. Incandescent bulbs produce light slightly more on the red side of the light spectrum.
Red light in the spectrum tends to encourage bud and flower growth and as such incandescent lights are better used on flowering plants. Because so much of the energy in incandescent bulbs is converted to heat there is a significant loss in light intensity. The amount of heat generated means they cannot be placed close to the plants to overcome the lower light intensity generated.
From the spectrum show below the spectrum above the 650 wavelength light can be effective at promoting robust stem growth, proper node spacing, and more flowers and fruit.
The issue is too much IR radiation is felt as heat and so can be damaging to the plants when the lights are located too close to the plants to increase level of illumination to prevent the plant from stretching for the light and getting leggy.