What exactly is this weird ''energy'' feeling?

[Dargor]

Although in rare cases I also experience this during the day when it's very quiet around me, it occurs most of the time when I'm laying in bed before going to sleep. I feel this ''energy'' or presence around the crown of my head area, and I noticed it usually shows up when my breathing is slow and relaxed. This feeling doesn't happen at will when I try to find it, but rather at it's own accord. This has been going on for quite a while and so far I have just dismissed it as my imagination. I know as much about all this spiritual stuff discussed here as I know about car engines, so any chance it could be something spiritual related? Thanks in advance.