MaxThrustPower, there is some information in your post about melatonin that threw out the BS flag to me. That study is 12 years old. One of the more ridiculous factoids was this one"

"Mistake #6: The dosage amount isn’t important.

The problem with melatonin is that it was discovered long before scientists really understood what it does and how much you need. For example, in the late 80′s and early 90′s, we thought melatonin was a sleep hormone. Now we know it is much more complicated. In addition, tablet sizes average 3-5 mg. New evidence shows that adult males only need 150 micrograms, and the average female needs only 100 micrograms (a microgram is 1/100 th of a milligram). So the average melatonin supplement is 20 – 50 times more than we need! If you are using regular melatonin tablets, you can cut the pill into fourths, otherwise, try to find the smallest pill size available. If you are taking time-released melatonin, do not break the pill, as this will ruin the time-release."

Honestly. While the dosage is very important, 20-50 times more than we need? So we need virtually none whatsoever? The smallest dosage pill (that I've heard of) is 1 mg. Which does almost nothing, for anyone at all. And by this study, it would be about ten times more than we need? Why bother?

"Experts" say you should only take melatonin for two weeks? This is old data.

It will only affect your performance in the aircraft if you are still under the influence. If you have taken melatonin at least 9-10 hours prior to flying, it should be out of your system.