Is it correct grammatically using "both X and Y as well as Z" such as in the example bellow:
Sleep deprivation can be damaging to both physical and psychological well-being as well as interpersonal relationships."
English Language Learners Stack Exchange is a question and answer site for speakers of other languages learning English. It only takes a minute to sign up.Sign up to join this community
The sentence looks fine. However, to stay clearer, I would prefer having a comma there.
Sleep deprivation can be damaging to both physical and psychological well-being, as well as interpersonal relationships."
As you previously said 'both' in the sentence, it should apply to only two things -the physical and psychological wellbeing. To introduce one more thing for that 'damage' when you have already mentioned two things following 'both', you need to have some preposition or conjunction.
Another way, as J.R. says, remove 'both' and simply separate them all with commas.