Spooks - when you come to look at such things as ghosts, we have numerous grey and white lady ghosts in our castles but can't think of many prehistoric ghosts, except for sidh fairies if you count them... so an 'experience' of a person/coldness/ disorientation etc at a megalithic site is subjective to the person's mind who is experiencing it..
I go along entirely with the idea of a 'parallel' world Squid Tempest - the 'other' we have'nt explained yet, but ESP is probably one of its phenomena... longbarrows seemed to have escaped the woo*** mythology, unless there is an unknown mysterious force in the stones* like there is down in supermarkets by the freezers....

*radon