Yes, I've SUFFERED from both hypnic and myoclonic jerks. If they get as bad as mine did, there is medication available.
As far as the Ambien, it helped mine the 2 or 3 times I took it. But, everyone's different. There is discussion about the Z-drugs at benzobuddies.org and by British neurologist Heather Ashton at her site. Google her name.
"O Lord my God, I cried to you for help, and you have healed me." Psalms 30:2