Is it normal for your blood pressure to rise when waking up from a nightmare?

Last night I woke up with a nightmare my heart was beating very fast and when I took my blood pressure it was 175 over 99. In a space of 30 minutes gradually went down so did my pulse which was 110 max but went down pretty fast. The cardiologist run tests a couple of weeks ago and everything seemed to be fine. I had blood test too and they came back normal. My GP told me this that it was a tachycardia and gave me a prescription of beta blockers a very small dose, but didn't say much else about it. I'm a bit confuse I don't know if the nightmare started the episode, could have been a nocturnal panic attack or the beginning of high blood pressure. My blood pressure is average normally, but I must say I had episodes like that in the past not often perhaps every 4-5 months and normally when I have been anxious about something. I don't like to take tablets if I know it's not life threatening I can calm myself down, bit I don't know what to do??