Sudden Shock To Heart At Night When Body Is Relaxed.
Thanks for posting your query.
I would appreciate if it's possible for you to describe your symptoms in little more details.
But what I gather from your description it's just jerky or thump kind of feeling when you relax and only for brief period without any associated symptoms.
It's likely to be an occasional ectopic which occurs in many people without any serious consequence.
Still, if you experience these symptoms again and again or develop any new symptoms, you may need to consider visiting your ECG (Electrocardiography), Echocardiography.
Holter monitoring can be done in case any positive findings are found in basic investigations.
I hope, I have answered your query. Please accept my answer in case you have no follow up queries.
Regards.