Song played on "Parasyte The Maxim" Episode 6 at time 16min30s I'm looking forward the name of the song played in the 6 episode at 16min30s.
It's when Migi explains that She has to sleep for 4 hours as She has healed him.
This song appears regularily in the episodes, and it is not in the OST (or I didn't find it).
The song you are looking for is the Migi Theme by Ken Arai

You can listen to it here 

This song does not seem to be included in the currently released OST