Yeah for instance I see blue when I hear middle C and other colors for pitch. Pitch and color are related in the way the brain interprets them as signals. Sometimes my synesthesia will even overlap on my visual plane and not just be restricted to the minds eye. Today in my Latin course we were learning about a new declension and a green polygon and a red circle kept surfacing in front of me.
Yes your suprachiasmatic nerve releases melatonin before sleep after the VPN initializes the induction of sleep. You trip every night (several times really, whenever you enter REM sleep) in the form of dreams but you rarely will remember them all.
Gravitational microlensing: when a blackhole moves in front of a celestial body thus disturbing its apparent magnitude from our frame of reference (e.g. (exempli gratia) if a Terr rotating blackhole moved in front of Sirius we would be able to detect it because its magnitude and position would be altered by the flux in space-time created about the event horizon). Can be detected easiest with x-ray telescopes since singularities theoretically crush matter and convert the energy source into x-rays which radiate towards Earth.