Yes, you'll wake up from your sleep due to uneasiness, pain, and lack of breathing. However, most heart attacks happen in the morning. This is because, in the morning, the body prepare itself for the entire day. Sometimes, this puts extra pressure on the heart and leads to a heart attack.
When the heart stops, it stops pumping blood throughout the body. All brain activity is believed to cease by about three to four minutes from the time the heart stops due to lack of oxygen
Yes, a person can get a heart attack without cardiac arrest. Heart attacks occur due to a blockage in the coronary arteries. However, heart attacks can sometimes lead to sudden cardiac arrest.