The first recorded abduction was Betty & Barney Hill in 1962. this abduction was is believable because there was physical evidence for it ( the car was magnetized) and the claim that they come from Zeta Reticulum as that star system was only discovered later so there was no way Betty could have known about it.
In the 1980s there was a lot of reports of abduction and most the cases were similar so that gave credence to abductions. However after that most people now know about abductions so anyone can make up a good story.
Most abductions follow this pattern.
The abducted is in bed and is woken by a bright light. they can't move. then they float up and may pass through a wall and then they enter the spaceship. In the spaceship they are experimented on and often sperm samples are taken in the case of men. women are often impregnated. the fetus is them removed during a latter abduction.
A lot of abducts claim to have met there offspring, being alien/human hybrids.
They are then returned to bed and remember little of what happened.
Some people claim to have been abducted wile traveling, they see a ufo then suffer lost time.
Most of the abducts find out about there abduction under hypnosis, this is a little suspicious as people are very suggestible under hypnosis.
There are claims of physical evidence like radiation burns and implants, but then other people say this evidence does not exist.
These abductions are similar to cases in the middle ages but they called them hags or demons.
One possible explanation is halogigmic hallucination, that is when you are between being asleep and awake. under these conditions you may be paralyzed, this is to prevent you from moving about in your sleep wile you dream, this happens during R.E.M sleep. Under these conditions it is hard to tell what is reality and what is a dream. Because of the paralysis a feeling of panic sets in. However this does not explain why people have the same dream.
Another explanation is that the brain is effected by electromagnetic radiation from high voltage lines, this also does not explain why people experience the same illusion