I take 1 mg of Xanax at night and the doctor prescribed me gabapentin for my aching legs, can I tak?

Click on the link: https://www.drugs.com/gabapentin.html

Yes, Gabapentin is used off label to treat other conditions, such as anxiety, etc..

Thank You

I have taken clonazepam and gabapentin together, both used for anxiety. I take clonazepam 3-4 times a day. I don’t usually take it at bedtime, but it is safe for you to take them together?

Remember that everyone reacts differently to medications ( benefits, risks,potential side effects, possible interactions, etc..).
What may work for you doesn't necessarily mean it will work in the same way with other patients.

Ok, I misread your question.

Did you tell your Dr. you took 1mg. of Xanax at night and was he/she ok with that fact?
If you did not inform your Dr., I suggest you play it safe and start the Gabapentin once your Dr. is aware you take a benzodiazepine at night.