Hi
Sofia,
You wrote: "Sanja .. is a form of
Sonja which originated as a nickname for
Sofia".
Yes,
Sonja (
Sonya, Ñîíÿ, female only) is a nickname for
Sofia (female only). Everybody in Bulgaria or Russia knows that. Nobody links that name with the Russian word for "sleep" = "son". Lots of people in Bulgaria na Russia know that
Sofia means wisdom.
However, Sanja is NOT a form of
Sonja. Sanja is a pet name for
Alexandra. Please see
http://en.wikipedia.org/wiki/Alexander#Variants_and_diminutives and find
Sanya on the row for Russian. If you can read Russian, please go to
http://ru.wikipedia.org/wiki/%D0%90%D0%BB%D0%B5%D0%BA%D1%81%D0%B0%D0%BD%D0%B4%D1%80 also. This page lists even Sanjushka (Ñàíþøêà) as a pet name:
http://ru.wikipedia.org/wiki/%D0%A3%D0%BC%D0%B5%D0%BD%D1%8C%D1%88%D0%B8%D1%82%D0%B5%D0%BB%D1%8C%D0%BD%D0%BE%D0%B5_%D0%B8%D0%BC%D1%8F.
In Russian, IMHO,
Sasha is a male pet name (
Alexander) and Sanja is a female pet name. I could be wrong as many Russian pet names are unisex.
Anyway, in Russia or Bulgaria, Sanja and
Sonja are never confused. These are two different unrelated names.
In Bulgaria, both Sanja and
Sonja are actually borrowed from Russian. True Bulgarian pet names are Sofka for
Sofia and Sashka for
Alexandra.