Утро вечера мудренее.

Google translates
Утро вечера мудренее.
as
Tomorrow is another day.
or
Sleep on it.
I get that this is probably an idiom, but the literal meaning of the words are:
мудрёный - sophisticated, tricky, intricate, strange, difficult
утро - morning
вечер - evening, tonight
So, stringing those words together it's hard to see how the idiomatic meaning is derived. Anyone have any insight into this?

I think мудренее is used here with the meaning «мудрее», “wiser”, “cleverer”.
“Morning is cleverer than evening”.

So it's more like "sleep on it" and yes, it's a proverb.