I have one next to my bed, that I turn on every night for around half an hour, to an hour. I cannot vouch for any other benefits except that it really is soothing. I have been been meaning to put one in every room.
Orange light (like the sunset) encourages our brains to produce Melatonin (a hormone vital to sleep); something which salt lamps provide, and normal lights do not. That is, unless you have one of those super old bulbs! Make sure you also alter the white light content of your phone/computer, as this can also help if you are staring at it late at night. There are many good apps for this too, although my iPhone has an in-built setting for it