Each year, fewer than 7 people per 100,000 experience “global transient amnesia,” a sudden but temporary loss of memory that can’t be attributed to any other neurological condition. The condition can be brought on by vigorous sex, as well as emotional stress, pain, minor head injuries, medical procedures, and jumping into hot or cold water. The forgetfulness can last a few minutes or a few hours. During an episode, a person cannot form new memories or remember very recent events. Fortunately, there seem to be no lasting effects.