The effects of melatonin are super noticeable. It's like taking drugs: you pop a pill, and feel different 30 minutes later. Melatonin makes me feel drowsy.
There is no placebo here. After 15 to 20 minutes, I always get irritated and ask myself: why doesn't it work?!
It does, just a bit later.
===== Vitamin D ======
Sorry that I'm sourceless on this. I read somewhere that melatonin and vitamin D are inversely related in their cycles of when they peak. Someone suggested to take it in the morning.
Regardless of whether the timing is off or right, vitamin D is needed to not be depressed [1]. So this part might be a placebo (like I care, I'm pragmatic) and at best it does something.
I do notice that it indeed prevents me from feeling like shit by virtue of sitting inside all the time. That also might be a placebo (I still don't care, placebo's are demonized and it's a competitive advantage if you accept it). The trend has been going on for 2 weeks now.
[1] Note: there are way more sources. I just did a quick Google search and picked the first URL I could find.
