You are absolutely crazy to accept a night turn on the third night after a ULR. You are finally settling into a night sleeping pattern after your body has been completely screwed by a 10-12 hour time zone change; ready to fall asleep at 9 or 10pm, and they send you off for a 12 hour night duty to India and back.
This has to be the most dangerous rostering pattern this company pushes.
On a number of occasions I've simply refused that duty due to fatigue. I will not put myself at risk of an accident by doing that sort of shyte. And many more people should refuse it too.