I've experienced a hypnic jerk many times over the years but in the last few weeks i've been experiencing something that is similar but not quite the same. It occurs at the same point, just as i'm drifting off and unaware of my surroundings and suddenly I will wake up (and by wake up I mean completely), with a slight, very quiet gasp and the feeling of having been startled as well as the sensation that I have been holding my breath (which was very scary at first). The strange thing is, I have no sensation of falling and no muscle twitches or jerks. This will happen seven or eight times before I successfully fall asleep. Once asleep, I sleep through with no problems and wake up feeling rested.
Is this a hypnic jerk too? Most definitions seem to focus on the muscle twitching so i'm not sure.
I also experienced mild 'Exploding Head Syndrome' the other night which seems a little too coincidental, so i'm wondering if it's all the same thing but happening in different ways? And why might it suddenly start happening every single night?