Running halogens at reduced brightness is bad for them because the halogen cycle requires that the lamp be hot enough (at least 70-80% of full power, third question down, also see the next one about dimmers and bulb blackening/failure) so that evaporated tungsten doesn’t get deposited onto the bulb, which explains the darkening and early failure.
That is to say, you need a separate low-power light if you want a night-light (it is also more efficient to have a small lamp at 100% brightness than a big one at 20%, plus the color temperature is higher, unless you specifically want the orange glow). For example, one of these lights, with a built-in light sensor that automatically turns it on when it gets dark. Also, the small 5-7 watt bulbs these lights use are exempt from the phase-out:
Also of note, you used to be able to buy 240 watt halogens that would give the same light of a 300 watt halogen. They were more expensive and didn’t seem to last as long in my halogen torchiere lamps so I quit using them. Now I can’t even find them online at the bulb places.
