If you cross into the US at a port-of-entry and are admitted as a visitor then you are good whether or not you took Melatonin supplements. If you enter illegally or associate with people who entered illegally, don't be surprised if you are caught up in a raid. However, even if you get detained, if you have no criminal history, you will get released after arrested because there are no more beds [1].
Seriously though, if you are going to make a cheeky reference to race, at least get the reference right. Melanin is responsible for darker skin [2].
[1] - https://www.newsweek.com/ice-seeks-more-bed-space-detainee-n...
[2] - https://en.wikipedia.org/wiki/Melanin