Diazepam, alprazolam, xanax were strongly associated with nighttime heartburn." is this correct?

Doubtful relation: Your question seems to be based on 1 study from arizona based on survey of people with night time heartburn. However in this study there were so many factors mixed that a definite co-relation is not proven. What is however certain that if you are prone to have hyper-acidity, many many foods and medications can trigger it. If any one does get heart burn at day or night should be treated for it.