Hi AP151....just wanted to let you know there are a lot of fellow twitchers out here (i'm one too) and I thump in the middle of the night as well...mostly after I turn over or use that muscle. I just posted an article for another friend here on AZ and maybe it will help you too...
Anxiety and stress are perhaps the No. 1 cause of muscle twitching, which is also known as benign fasciculation syndrome. Benign means the muscle twitching will not develop into anything serious. Fasciculation is the medical term for muscle twitching. Syndrome means that typically, a lot of muscle twitching is also accompanied by muscle cramps, muscle aches and some tingling. But these other symptoms come on after the person starts excessively worrying that the muscle twitching is a sign of a deadly disease.
Anxiety makes muscles twitch. It's that simple. One theory is that in ancient times, early man had to always be ready for action, living in a harsh environment with no modern-day conveniences to protect him. His muscles, his entire nervous system, had to always be prepared for a fight with danger, or for a flight from danger.
In the genes
We are genetically hardwired to physiologically react to a crisis situation. Our muscles are on standby to jump into action. But contemporary stress is different from ancient stress. Today, we don't need to be ready for the charging bison or hissing snake. But just the same, our bodies are under siege by other forms of anxiety: job stress, paying bills, foreclosure threats, protecting teens from drugs and sex, marital problems, traffic jams, business meetings, etc. It's no wonder that our muscles are always jumping.
When we are under chronic stress, our muscles twitch because they think that at any moment, action will be required of them. So they are, in a sense, gearing up for the fight or flight, kind of like a track sprinter dragging his foot backward on the track as he prepares for the race. Anxiety tells the muscles, "Get ready. On your mark, get set..."
But the "go" never happens, because the stress is not of a life-threatening nature (such as a charging bison, falling rock or hissing snake of ancient times). So the muscles remain in idle, like a car at a stop light. The engine is on, but the car goes nowhere. The engine, in this case, is the muscle twitching. They are not relaxed. They are anticipating.
So when you notice a lot of muscle twitching while under stress, realize that this means that everything is working just fine.
Hope this helps and just know you aren't alone.