Go to www.philips.ca, click on the lamp model you want, click on the Specifications tab, and it should list the bulb type.
For example, on the specifications page for my HF3470/60: http://www.philips.ca/c/light-therapy/h ... ifications
Let's take an extreme case. Say I never use it for bedside illumination/reading/mood lighting, but if I oversleep by one hour every day with my lamp at full blast trying to ease me out of bed, that's still eleven years of life expected on the bulb. And when it dies, it's three dollars to buy a new one (I did a Google search for the bulb type and was surprised how cheap it was).Lifetime of lamps: expected >4.000 hours
Type of lamps: Philips Halogen Lamp 100W, 12V, GY6.35
With an eleven year life on this bulb, I'll probably die from my unhealthy undersleeping habits before this bulb dies.