Sunlamps are high on the UV side. Plants can receive sunburn just like humans. While they are more tolerant of UV rays, constant exposure can result in a plant loosing needles/leaves.

I have a yew what is 'sunburned' on its south (sun facing) side. The top needles are brown (dead and dying) from being newly exposed to full sunlight after the oak tree came down.

UV exposure and the effects on plants: [link to www.sciencedaily.com]

You can use a regular florescent tube light (more than one of course) the modern florescent tubes give off strong, full spectrum light and the plant will adapt to a wide variety of visible light spectrum and even a less wide brightness/dimness spectrum.