I've been dosing small amounts (10-30 mg or so) sublingually before bed with melatonin at roughly the same dosage pretty much every night for around 3 years now. It's been a great experience. Dreams are intensely vivid every night, I wake up feeling well rested, refreshed, and ready to meet the day. I've noticed a lot of the same benefits as reported from microdosing other substances: improved mood, increased creativity, heightened awareness and flexibility of thinking, etc.
The reasoning behind taking it at night is that it aligns with the bodies natural processes. When you go sleep your body stops producing serotonin and starts producing melatonin which is metabolized into pinoline and sets off an endogenous cascade of production of other beta-caroblines and tryptolines throughout the sleep cycle.
A few times a month or so I add a little microdose of psilocybin to the nightly harmela.
The daily low dosing does seem to make things go more smoothly with larger doses when I drink ayahausca or take full/psychedelic doses of harmala. There is certainly a level of adaptation that takes place in regards to nausea/bodyload/vertigo effects, not to be confused with tolerance, harmalas (at least for me) seem to exhibit a strong reverse tolerance.
I won't recommend this regimen for everyone, I'm very much a guinea pig here, but thus far my results have been nothing but positive and I do intend to continue the experiment long term.