Carmen Electra made a massive life change this past week -- filing to ditch her birth name to formally go by her long-known stage name ... and now we know exactly why.

Sources close to the "Baywatch" star tell TMZ ... there's really no big reason behind the decision -- we're told it's just something she's been thinking about for a while and finally took the plunge, since there's no better time than the New Year to start fresh.

We should note, she hasn't gone by her birth name -- Tara Leigh Patrick -- in decades.

TMZ obtained the legal docs earlier this week ... revealing she wants to formally change her name to "Carmen Electra" ... so looks like this is officially goodbye to Tara! It's also just formalizing what everyone has known her as for decades now.

Fun fact -- CE didn't come up with the zippy stage name herself -- it was actually birthed as a result of the late icon, Prince ... who bestowed the name upon her when she auditioned to be part of an all-girl group he was assembling in the early '90s.

Unfortunately, she didn't make the cut ... but she went on to make a splash on TV and elsewhere, and she kept the cool moniker for herself.

Also ... she never assumed the names of her hubbies while she was married, so her becoming Carmen Electra in court is just a no-brainer. No better time for change than the present!