Fast heart rate while sleeping, wakes me up - dysautonomia? Hi folks, This is my first message to ask a question about one of my ME/CFS symptom. This is probably going to be a long message but I'll try to make it as clear as possible. One of the symptoms that has been increasing a bit over the past few years is rapid heart rate while I am sleeping, usually in the early morning hours (4-6 AM), beating fast enough to wake me up. For example, one instance of this showed up on my last holter monitor as 134 beats per minute at about 6 AM. Sometimes it happens more than once (2-3 times) in the early morning. I'm able to fall back to sleep but it is very disruptive to the sleep. First, I should mention what this problem is not. I have had another type of tachycardia, AV nodal reentrant tachycardia, since I was about 11. That problem, while annoying, is not at all disabling for me. It is apparently caused by a short circuit in the heart. It feels quite different. First, the switch from slow to fast heart rate, and back again, is within a single heart beat. Second, when that type of tachycardia happens the heart rate is a lot faster, around 180-190 beats per minute, not the range of 100-140 beats per minute that wakes me up. Third, while it has happened a couple times during my sleep in my lifetime it almost always happens while I'm awake. I've had this other type of tachycardia for almost 40 years now so I know what it feels like. I generally just rest for a bit, or try the Valsalva maneuver (that works sometimes), and it usually goes away by itself after a few minutes (there are a few times when it has lasted longer, up to 20 minutes, but that's another longer story). So, back to this new type of rapid heart beating, the kind that wakes me up while I'm sleeping. I assume it is part of my range of problems with the autonomic system. I have a type of OI (Orthostatic Intolerance) called by various names, e.g., NMH (Neurally Mediated Hypotension). I've had two different abnormal tilt table tests (one in 1995, another in 2003 due to the evil disability insurance people) and my blood pressure dropped to something unmeasurable after 20 to 30 minutes. And while I did not seem to have POTS when I was first diagnosed with NMH back in 1995, the last few times I took my blood pressure while standing up (another long story, again related to evil LTD insurance people) my heart rate was quite variable but was as high as 150 bpm. Back to the OI issues, I understand (sort of, LOL!) that body postures of sitting or standing stress the body and cause blood pooling and that affects the body's ability to regulate blood pressure and heart rate. And getting overheated, eating a full meal (blood goes to the stomach) and a few others triggers can cause symptoms for me, too. I watched that recent CFIDS Assn sponsored webinar not long ago and unless it was in the Q/A section (I cut out before that section) I didn't see anything about rapid heart rate while lying down and fast asleep. Anyway, what I don't understand is what is happening while I'm lying flat, asleep, that is causing this rapid heart rate that wakes me up. It's not anxiety. It's not a nightmare. I just wake up and wonder, huh, why is my heart going this fast? I often feel too warm so maybe that's part of it--my body is trying to cool off and it can't? I throw off the covers to try to cool down. Then I thought, could it be sleep apnea? But I thought I read somewhere that the heart actually slows down when that happens. And it doesn't feel like I'm gasping for breath (and my husband has not noticed that, either). Sometimes I get up and drink some ice water. What's strange is that as I get out of bed my heart rate SLOWS DOWN, which is odd, because that action requires more physical exertion, minor as it is, than just lying still. But why would moving around make the heart slow down? But even if I'm really too groggy to think or move around, and I just lie there in a daze, my heart does slow gradually after I wake up. So, I guess I have two questions: 1. Has anyone else, especially those patients with some form of orthostatic intolerance, ever had this symptom? 2. Do you have any guess as to what might be causing it? Or how to prevent it? I'm obviously going to mention this to my doctor at my next visit but thought I'd ask some fellow patients for their thoughts. Generally, my doctor is very supportive but I think I need someone who is a specialist in autonomic dysfunction. I've been avoiding trying to find yet another specialist (I really don't like going to doctors) but it's time to stop ignoring this symptom now that it is happening more and more frequently. Thanks!