。
You shouldn't stay up late every night.
Literal
Every-night late [until-まで] wake-up-stay-[concessive-ては] is-not-good-[いけない].
起きている combines 起きる ('wake up, get up') with ~ている to yield the stative 'be awake, stay up.' ~てはいけない ('must not X,' 'you shouldn't X') is the prohibition pattern — built from the concessive ては + いけない ('won't do').