You could be choking on the acid.  The posts above are all good ideas for helping control the acid.

Try some over the counter acid reducers.  Two weeks of Prilosec may do wonders.

Don't eat late at night.

Prop your head or upper body up slightly with pillows.  Or you can tilt your whole bed by putting supports under the head of the bed.

Try eating crackers or other non-acidic food before you lay down.  Just a few.

Don't drink pop or coffee after supper time (about 6pm).

See your doctor if none of these work!

It is pretty tough heartburn when it wakes you at night like that.  I have had that happen to me, also.  They wanted to do surgery, but I didn't.

Try controlling with some of the OTC medicines.  I am having good luck with Zantac (generic), and may try the Pepcid AC next (generic). 

I keep Tums by my bedside and take some before I lay down, and if I feel the need in the night.  You may be able to use other instant antacids, but I cannot take the ones with Magnesium in them.  The magnesium is a stimulant and it works well for me!  LOL!!

Wow, that is pretty bad.  I don't know if I would drink a big glass of milk right before bed but it might help.  I would take saltine crackers up with me to bed.  They usually help with acid.

When you have really bad acid reflux, try eating something that isn't acidic like a couple of celery stalks.  That's neutralize the acid and provide some relief.

This is probably just the acid creeping up your esophagus when you are lying down. Try elevating your pillows a little bit and maybe having a big glass of milk before bed.