The Black Hole Effect or BHE may occur during a failed WILD attempt, so named because of the feeling one has when becoming aware of passage of time after surrendering to the realization that a WILD technique is not working.
Relaxing the body and mind to accommodate an induction can relax an awareness of time as well. For this reason the BHE is much stronger and more likely to occur during a prolonged induction attempt.
The first known usage of the term in this way was by Classico, a member of Dream Views.
He described it as follows:
- The type of failed attempt I just had I like to call the 'Black Hole Effect.' You get relaxed, nothing extraordinary, and concentrate on your breathing. Hypnagogic images start to appear at some point, sometimes even with Low Definition Viewing- yet it fades and you suddenly realise "This isn't going to work" and get up... ofcourse the clock is ahead two hours and you have no idea what happened to that last hour.
- I remember my dreams everynight, so I'm fairly certain I didn't just fall asleep, so I think I inadvertently relaxed my conscience to the point of losing self awareness to an extent. 
A BHE is not strictly because of a loss of consciousness. Nor should it be confused with a mysterious feeling of lost time.