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Missing time is a proposed phenomenon reported by some people in connection with close encounters with UFOs and abduction phenomena. Others believe that missing time is related to or caused by poltergeists, time slips, or other paranormal events. The term missing time refers to a gap in conscious memory relating to a specific period in time. The gap can last from several minutes to several days in length. The memory of what happened during the missing time reported is often recovered through hypnosis or during dreams.
Possible causes 
- The subject is mistaken about the time, such as a departure time, so that an event seemed to take longer than it actually did.
- The memory of the event, real or imagined, is traumatic so that the mind represses it. The concept and reality of repressed memories is debated among psychoanalysts and scientists, however, and many do not support the concept at all.
- The event itself did not happen and the subject instead imagined as part of a hallucination caused by drugs or a seizure (Absence seizure), or implanted during hypnosis.
- Highway hypnosis, or losing track of time while driving and having one's mind distracted.
- The person slips into a trance similar to Highway Hypnosis under duress, stress, or similar circumstances in which conscious memories are no longer created; during this time the person can perform normally but have no memory of the actions they performed.
- They could experience a case of Hypnagogia with out fully realizing it, similar to how one might doze off in the middle of something and have no recollection of the time between just before falling asleep and awaking.
- Controversially the event is real, and the time was lost due to the Twin Paradox predicted by Einstein's Special theory of relativity: If the abductee was taken into the UFO which then flew into space at very high speeds, forming a loop trajectory eventually returning to Earth and letting the abducted person free, time would be subject to relativistic effects. According to the special theory of relativity, while many hours or days have elapsed on Earth, the elapsed time experienced by the occupants of the craft will be much shorter if the UFO traveled at a sufficiently high velocity. Although the Twin Paradox itself is widely accepted as correct and true in physics, this explanation does not prove that UFO abductions themselves are real. It merely provides a plausible explanation for the missing time, should the abduction (or voluntary travel by a future man-made spacecraft) indeed occur. It is in fact questionable that abductees reach relativistic velocities during their abduction: Extremely high accelerations would kill human beings, while accelerating at endurable rates (a couple g) will only reach relativistic speeds after several months. Furthermore, should an abduction have occurred, this would not explain the inability to remember the events which took place on board the hypothetical spacecraft, events which would, to the traveler, seem to pass in real time -- simply in less time than was "missing". Paranormal events such as UFO abductions are highly contested. See, for example, the evidence and skepticism for the five-day missing time in the well-known Travis Walton case.
- Alternatively, it's thought the subject is brainwashed of certain events by the UFO crew. For example, in the Hill abduction the couple may have had their memory erased from the time the abduction began until they resumed driving.
Other occurrences 
A phenomenon similar to missing time can occur while listening to binaural beats designed to produce altered states of consciousness. In this context, it is common to the extent of being listed as a frequently asked question in the Monroe Institute's Hemi-Sync FAQ, where it is referred to as "clicking-out".
See also 
- Watson, Nigel (2005). "The Hill Abduction", SkepticReport.com.
- Richmond, Raymond Lloyd. "A Guide to Psychology and its Practice: Repressed Memories.", GuideToPsychology.com.
- Kaufman, Carolyn. "A Brief Explanation of Dissociative Identity Disorder (multiple personality disorder)", ArchetypeWriting.com.
- http://www.monroeinstitute.org/hemi-sync/faqs/[dead link]