Itchy vulva for no reason

Shara
About once a week I will get an itchy Vulva but it won't be irritated or infected or follow with any discharge. It does get really itchy and annoying though!  I'm not to worried about it. Sometimes I think it could be the undies or pjs I'm wearing or that it's late at night and I haven't changed my undies yet. Does anyone else get this?