I used to get these, too. The second I'd start to doze off, it's like something would startle me and I'd get sick to my stomach. Sometimes the sensation was brief...sometimes it would set off a chain of events that would keep me up all night long.
There are drugs that you can take for this, and I'm pretty sure they'd take care of the problem, but since your primary condition is depression I don't know if you're the best candidate. You could ask your doctor, though. Short-acting benzodiazepines...a small dose just at night before bed. They're indicated to treat anxiety and panic disorder.
You may also check out the "relaxation techniques" thread in Healing Well's Anxiety/Panic forum. Some of those may help.
Good luck. I know what it's like to have this and it's certainly not pleasant.
Edit -- spelling mistake
My Brain: My friend, My enemy: A blog to chronicle my attempt to recover from anxiety/panic disorderanxietypanicdisorder.blogspot.com/
Post Edited (debaser) : 5/10/2007 4:05:19 PM (GMT-6)