You can get 300mcg pills but they never seem to be the sublingual, dissolving type. The lowest I've found dissolving tablets is 1mg. I take a half or a quarter and dissolve it under my tongue. That works fine when it works. Sometimes it puts me to sleep and I sleep longer than my usual 5-6 hours while waking up with a hangover. Sometimes it just makes me sleepy for 15 minutes and then I'm wide awake. Melatonin is very hit or miss for me. I smoked a lot of pot though, and from what I hear that triggers a massive melatonin release, so maybe my homeostasis is a bit messed up.

Sleep is tough. There are so many confounding factors and issues which can affect it... it's hard to find a single thing that works or that works consistently without side effects.