Lighting requirements for your gecko.
Cresties unlike other reptiles do not need the additional support of a UV emitting Heat Lamp. Those other lizards need the Heat lamp as a basking source as they warm up their entire body using it; but also require the UV radiation from it in order to synthesise enough levels of Vitamin D3 to enable them to function biologically.
The Crestie does not need this requirement - but I tend to use a light in the Terrarium hood during the winter months to give them a better representation of daylight and night-time, mimicking their natural habitat. It must be said though it's probably more for my benefit than theirs!
Lighting = additional heat!!
Light comes with the side effect of additional heating - bear this in mind as your geckos will gravitate towards the light-bulb at the top as they seek out the heat- so ensure it is not too hot and not touching the top of the Terrarium mesh or your geckos can and will get burned and severely dehydrated - again the exo terra hoods provide a safe way of putting lights above the Terrarium and you would then only need to watch the heat levels and choose a suitable wattage bulb to control the heat.