Could be sleep apnea. This is when your throat collapses while you sleep and you can't breathe, so you wake up, usually gasping. You should get your regular doctor to refer you to a sleep clinic. They can monitor you for a night while you sleep to see if you have sleep apnea or not.

If you do, there are very effective treatments. For mild to moderate, there is a dental appliance you can wear that keeps your jaw in line so your throat doesn't close. For moderate to severe, there is a machine that blows air continuously into your airway so you don't stop breathing (called a CPAP machine)--don't worry, you get used to it. There are also surgical options, but they'll try the non-surgical first.

That would have been my guess too .Sleep apnea .Very good treatments available.
Good luck.

Also, if you are over-weight, losing weight can help with sleep apnea.