My doctor gave me melatonin to help me sleep. So if melatonin makes you sleepy, is that why black people are always late?  Becuase they like, already have it in their skin?
I think you're confused, or are you making a joke?
Yeah, maybe they are just late because they don't have to get up early for work. Too bad about them.
They have melanin in their skin, not melatonin. I can't tell if you're being serious, but if you are, you shouldn't assume black people always run late.