You have some condition that induces dormancy. When triggered, should try to seek out a safe place to rest as you will fall asleep within the hour and cannot awaken once you have fallen into dormancy.
The conditions are almost always predictable and regular, something no group of investigators can induce. Vampires commonly have dormancy weakness during the day, ghosts may have a dormancy weakness at all times except the hour after midnight etc. You always know ahead of time that you will become dormant, giving you time to seek shelter.
When forcibly awakened from dormancy (such as by an attack), you suffer four points of Impairment. For each sequence after that in which you were awakened, this penalty is reduced by one, but never to less than one point of impairment