This is very weird... when i wake up from a nightmare i can hear my fast heartbeat on my ears like blowing at the same rhythm of my heart beating.it only last for less than a minute. but this only happens when i have a nightmare what is this?

It is normal. It is not unusual to "hear" you heart beat when a person has palpitations as would be the case with a nightmare. For healthy diet: http://www.choosemyplate.gov/., exercise 30 minutes/day, drink enough water daily so your urine is mostly colorless, have safe sex, no tobacco alcohol weed or street drugs. Get Covid vaccine. Wish you good health!