When my brother (I will call him Edward) was a little boy -- from the time he was three years old until he was 11 -- he suffered from hypnagogia. Hypnagogia is defined as visual and auditory hallucinations on the periphery of sleep. Transition to and from sleep may be attended by a wide variety of sensory experiences. These can occur in any modality, individually or combined, and range from the vague and barely perceptible to vivid hallucinations. ... Wikipedia
In my brother's case, the hypnagogia took the form of "shadow people" or more specifically, a man dressed in a dark outfit, wearing a hat. This manifestation of shadow people is apparently quite common with children.
During hypnagogia, a person can be conscious and aware of their environment, but also in a dream-like state where they can perceive images from their subconscious. People experiencing waking-sleep commonly report the sensation of lights or shadows moving around them, as well as other visual hallucinations. A feeling of dread is also a sensation that occurs when experiencing hypnagogia. Hypnagogia is sometimes known as 'the faces in the dark phenomenon' because those who experience this state commonly report seeing faces while experiencing waking-sleep. Similar hypotheses have been put forward linking this condition to a number of other apparent paranormal experiences, including alien abductions, paranormal nocturnal visitations, and religious experiences such as contact with angels or demons. ... Wikipedia
My brother said the man never harmed him or attempted to harm him. He looked at him for a few minutes and then left. He visited every two weeks, like clockwork. My brother shared a bedroom with our older brother (I will call him James), who never saw the shadow person. Only Edward saw him. When Edward saw this illustration here, he said that was exactly what he saw visiting him. When Edward was 11 years-old, he had a calcified growth on his upper arm, which required surgery. As soon as the growth was removed, the shadow person stopped visiting him.
I am a natural skeptic, and I believe there is a plausible scientific explanation for these visitations. Hypnagogia would explain it, but my brother is convinced it was something else. To him it was too real, and too terrifying. When it was happening to him, he tried to explain it to our parents, but they did as all parents do and told him it was nothing. How often do we discount the "monster under the bed". "See...? There's nothing there."
"Yes, there is...!"
Apparently hypnagogia is more common than we think. We have all occasionally experienced auditory sensations just as we are drifting off to asleep, or the sensation that we are falling, and our body suddenly jerks. I don't have an answer or an explanation for what my brother experienced. But I do know I am going to sleep with my light on tonight.
Have a good sleep...