Is nocturnal catamenial epilepsy life threatening? (in a 27 year old) even tho sizures occur infrequently and are managed by medication so far. but their occurence during sleep could be lethal?

You may be referring to SUDEP (sudden unexplained death in epilepsy) which most often occurs in patients not taking their medication or being sub therapeutic. If you are still having seizures, consider changing your medications and/or implanting a Vagal Nerve Stimulator. Your neurologist should be able to help, but you may consider a second opinion if necessary.