miserable re pumping.

tried really hard to wake up every 3h to pump in the night but i just fail. so exhausted i don’t even hear the alarm even though i am a light sleeper. managed to wake up only every 4.5 - 5 hourly to do so. few like a really bad mother. anyone has similar experience or advice re pumping? i’m afraid to get engorgement esp after my post natal massages end. but i m really just so tired. in the day i always make effort to latch baby when hungry. i just NEED a decent sleep at night for just at least 4 hours a stretch. feel like i can’t go on to bf.