My nose is constantly blocked sometimes i can't taste anything or smell anything, its been like this now for about three years. i went to my doctor about a year ago and he told me it was the start of hay fever, but i dont think it is hey fever coz i still have these problems.
Does anyone know what it could be??
Sounds like night terror to me. Having an elevated heart rate and increased breathing rate when your body is in "fight or flight" mode is completely normal. It doesn't sound as though your symptoms are caused by an arhythmia, rather that your sleep cycle/dreaming induced an adrenaline reaction.
I would go to the doctor. He/she will likely order a CAT scan to rule out any abnormal neurological component. After that, he/she may suggest a sleep study. Barring any abnormal results, you will likely be advised to seek counseling or to take medication that will help alleviate whatever anxiety inducing emotions you carry with you into your sleep cycle.
Good luck.