For people taking drugs...like SSRIs with insomnia...I'd test it out by taking 3mg of melatonin at night for a month.

It will take a while for the melatonin to move around and work. It is a slow solution, a more natural one. So getting "knocked out" quickly will not happen at first, and duration may be shorter than traditional strong sleep inducing drugs.

But if there is some improvement, I'd consider getting the B12 tested to see if she is low in that.

It is not safe to take serotonin boosting things, when on SSRI's.

Also any light at all, at night will shut off any melatonin you make and prevent getting back to sleep properly. Do not turn on overhead lights, to use the bathroom. Have nightlights in place.
We found little motion activated lights you put along stairways, (we have lots of stairs) to light your way at night. And I have a little night light in the bathroom. So as we age we tend to get up at least once at night to relieve ourselves, and if you put a bright light anywhere along that path, your sleep than night may be gone!

Ours are GE Auto night lights-- with a rotating head. We have them along the hall and stairs plugged into an extension cord set up. Item 50311
http://www.amazon.com/50311-Directio.../dp/B000089DCL
Hubby buys ours at Kroger's.