I was not officially diagnosed with narcolepsy when I was younger and still haven't. However, even in my junior high and high school years and on through my college years staying awake was always a struggle for me. maybe the gluten was a factor back in junior high and just didn't realize it. There were times in church and other times I would just BAM fall asleep without warning. Frustrating and somewhat embarrassing to say the least. Now that I have been off gluten for close to a year now, the "feeling" of needing to sleep is becoming less and less. Still have periods of sudden sleepiness, but not as often any more.
when they first came out, I read the ingredients on them, and they don't seem to contain malt. But the company, at that time specifically posted on the website that they are not gluten-free. So I don't drink them.
Rum is naturally gluten free, but in cases where it is flavored, spiced, etc. you have to be careful where they might add a malt in the natural flavorings. I been using Admiral Nelsons coconut rums in cooking for finishing off stir frys, and adding a bit of flavor to caramelized ingredients for a few years now, I have never had issues with those.
As for the Morgan, I would be careful with the spiced version as they might use a malt based ingredient in it. I did a bit of research and like you found no conclusive evidence to if it contains gluten or not. The plain rum from them is listed on many and been tested by several groups and has come up gluten free.
On a side note if your a celiac or have intestinal damage I would avoid alcohol or drink in moderation. I personally only use it in cooking.
It seems they advertise it as a malt beverage. Malt is made from barley normally, so it would not be gluten-free. Unless they specify the malt is corn malt, it is always assumed to be barley malt per FDA labeling regs.