[Figment]

Not to mention instable chemistry leading to personality and psychological disorders being treatable with medicines to a certain degree.

'Ghost' sightings can be caused by a sound frequency of around 20Hz which can cause a blurring in vision, particularly in the peripheral vision. As humans want to see patterns in everything, especially instinctively look for human patterns for survival and social reasons, it is not strange people interpret things in something they can relate to. Same with sounds they can't interpret immediately.

Now, this doesn't explain everything away, but my impression would be that if there was such thing as ghosts and souls, we are not seeing enough of them. I also question the credibility of stories of traumatic events leading to ghosts returning elsewhere and perform certain routines or certain things they liked to do, or interact; As all those things are rather demanding on capabilities. Besides, if that were an echo of a soul or bodily energy, why would that be limited to dead humans?

To me ghost routines sound like conditions are met to make a house get into a specific climate state that induces certain observations. Mostly a building constructive thing and I don't mean like Ghostbusters skyscraper architecture.