Has anyone experienced this and it not meant something terrible? I'm very panicked!

For several weeks now I've woken up at all sorts of hours of the night - either woken up on my own, or been woken up by noise - and almost every time my heart is absolutely racing (I measured 150bpm the other night) and I'm usually sweaty. What is happening?

I'm on Sertraline - any chance this could be the cause? I'm currently freaked out about bowel symptoms and worried I could have bowel cancer. I'm not sure whether to worry this could be related (night sweats and cancer?!), or whether to worry about heart problems! I laugh at myself, but I'm equally terrified.

Any and all reassurance, particularly from others who've experienced similar, is very welcome. Thank you.