There is a high correlation between sleep apnea and atrial fibrillation. I am one such case. If your heart races during the night to try to keep you oxygenated while you can't breathe, it eventually develops a disordered state called atrial fibrillation. The sensation starts as a fullness in the chest, followed by thumping and bumping in the chest wall and a rapid, irregular, pulse. If you have a smart watch such as Galaxy or Apple, you can set it to detect your heart's rhythm constantly and to alert you if you have AF at the time. It uses up the battery charge in a few hours instead of a whole day, but for the two or three days it takes to get an indication, it is worth it. You can download the record from your watch and send it as an email attachment to your doctor.

There is a device, not very expensive, called a Kardia. You need to place a finger of each hand on its metal pads, but it does a good job of detecting heart arrhythmias as well.

If it turns out that you do have AF, don't panic. It won't kill you. It will make your life less worth living if you are constantly barraged by the sensations, especially if they interfere with sleep. Some sufferers find that it is during bed-time that their AF commences for the day. However, AF tends to be progressive, and you want it treated and managed before it progresses to more intractable forms such as persistent or permanent.