I Only Get Acid Reflux Pain At Night. Could I

I only get acid reflux pain at night. Could I take 40mg of omeprazole before dinner? At the moment I take only a 20mg dose regularly before dinner, even though the attacks are intermittent.
Can you explain why this pain generally comes after I have been in bed for several hours and at least 6 to 7 hours after I have eaten my dinner. And in spite of the fact that the head of my bed is raised about 6 inches? I get some relief by taking gaviscon when I am awakened by the pain.