Racing heart beat after yawn in middle of night. Why?

Since December, 2009, I've been waking up almost every night with a rapid heart rate.  If I remain lying down, I can keep it from going over 100 beats per minute.  But, if I stand up, my heart rate will go faster and faster.  I timed it one time for 15 seconds.  It was 50 beats in 15 seconds (200 bpm)!!!  I don't stand up anymore.  The doctor attributes this to anxiety/panic attacks.  But I almost never have them during the day.  Lately, when this happens at night, I have pressure in my chest, too, along with the usual tightness in my arms, legs neck, chest and tingliness in my jaw.  I also feel a deep darkness like I'm going to die.  I've had problems at night for over 18 years.  But they have never been this severe.  I used a 30-day monitor throughout January.  It showed that my heart gradually increased in rate.  However, I don't think I ever thought to push the button at the very beginning of the acceleration when I yawned.  Maybe there was a sudden change at the initial onset of the event.  I wish I knew what my heart was doing right before this started.  I wonder if it stops, and that is the reason I yawn and the rapid heart rate follows.  I wonder if I stop breathing, which causes me to yawn and then causes a rapid heart rate that is trying to correct a lack of air.  I wonder if this is a symptom of sleep apnea.  Sometimes, I wake up feeling great.  I lie in bed waiting to go back to sleep and feel a rush throughout my body, as if adrenalin just pumped in.  Then my heart rate increases.  This scares me also, but does not concern me the way the yawn followed by a rapid heart rate and no adrenalin rush concerns me.  The rapid heart rate after a yawn terrifies me.  In this case, the adrenalin seems to follow the rapid heart rate, which seems to be causes by the yawn.  I wonder if I should ask to have a sleep study.  I wonder if I have a serious heart arrhythmia that did not show up on the 30-day monitor, because I didn't have this particular sequence of events in January, and if I did, I didn't think to push "record" at the beginning, but rather during the increasing heart rate.  I actually feel tightness and pain inside my chest, and over the years, I could always rub my the outside of my chest to feel better.

[julieph85]

The exact same thing happens to me almost everynight. I think the same things and have gotten the same answers from doctors. I have seen so many specialists and everyone says it is something wrong with my autonomic nervous system but no one is sure what. I had a two week event monitor for my heart and it show sinus tachycardia at night sometimes as fast as 180 bpm. I also experience the rush of adrenaline feeling and I get nausea and abdominal cramping when the tachy is about to end. I also wake up gasping for air feeling like i'm being suffocated and then my heart will race for about 10 minutes. I also thought this was apnea because my husband has witnessed me stop breathing in my sleep he also said he has seen me gasp in my sleep. I did a sleep study and it came back normal. I'm not sure what to do because this problem persists and it is very terrifying and debilitating!