Brief Answer:
Various causes; all listed sir

Detailed Answer:
Hello sir and welcome.

Thank you for writing in.

There are various causes for flutters or palpitations that take place during the night. Let me list all the causes for you:
-Abnormal electrolyte levels (eg. sodium, etc.)
-Heavy meal containing high amount of nitrates, monosodium glutamate, fats, sugars, carbohydrates, etc. (this is usually the cause when night flutters are not commonly experienced, and most patients report a heavy meal for dinner)
-Panic attacks (triggered by stress, strong emotions, etc. (one of the most common causes)
-Physical activity (usually vigorous a while before bed time)
-Medical conditions (eg. dehydration, anemia, low blood pressure, low blood sugar, etc.)
-Medications (among which medications to prevent irregular heart rhythms are also present, something you may be able to relate to, based on the history provided)
-Caffeine, nicotine, alcohol, other drugs, etc.
-If more recently developed and no relation to other causes on the list, then serious cardiac conditions should be considered
-Nutritional or herbal supplements
-Hormonal changes (more common in women)

I hope you found my response helpful and informative sir. Please feel free to write back to me for any further clarifications, I would be more than happy to help.

God bless.

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