I think you are askin two things
1. How do you ensure you wake when you hypo in the night?
2. How do you avoid hypos at night?
I believe the best way to wake when you have a hypo is to have good hypo awareness. If you have started to lose this, you can retain your body by increasing your average BG for a week. I am not talking about raising it a lot just st increasing your target from say 5.5 to 6.0.
I also find that I am often half awake when I hypo in the night. My natural tendency is to roll over and go back to sleep which results in those nasty hangover-type headaches that you mention. But, if I force myself, I can wake up, take a BG reading and treat my hypo.
Avoiding a hypo at night is down to working out why you hypo. Is it because you went to bed with a low BG? Is it because you had too much insulin on board when you went to bed? Is it due to a post exercise BG fall? Is it due to a basal peak (e.g. Lantus profile is not flat). Is it alcohol related?
If the reason is a low BG before bed or too much insulin on board, have a small snack such as a biscuit or even hAlf a biscuit.
If it is due to exercise or alcohol, reduce your basal (and maybe have a snack).
If it is due to a basal peak, change the time you take your basal.
God luck with your analysis.