Brief Answer:
Here are some suggestions for dealing with the insomnia and anxiety.

Detailed Answer:
Insomnia can be caused by a number of things, but as you have already noted that you have anxiety, and that Xanax works for both, I am going to assume that the insomnia is related to the anxiety.

If Xanax works well for you for both, it is not unreasonable to take it occasionally, although some doctors are hesitant to prescribe it in any ongoing way because the doctor can be called to task by review boards.

If your symptoms are ongoing and happen frequently then it would be wise to address the anxiety. Regarding medications, an SSRI such as Lexapro/escitalopram can decrease the anxiety long term. It is not a relaxant or sleep aid specifically, but if you can get the anxiety under control with it, you will likely be able to sleep better.

I mention escitalopram because it has one of the lowest side effect profiles.

With SSRIs, it is best to start low and slowly increase the dose. It can take a few weeks to see benefit, and in the meantime, Xanax can be used to help until you are feeling better.

Cognitive behavioral counseling can be very helpful too. And regular exercise is helpful.

Benzodiazepines such as Xanax have been implicated as increasing the risk of Alzheimer's disease later. But likely it is still safe to use it for a short time while you are getting to a therapeutic level of an SSRI or for occasional use.

I hope this information helps. It is miserable to have either insomnia or anxiety! Please let me know if I can provide further information or clarification.

---