NON-DREAMERS

Whether they are reliving childhood anxieties or visiting imaginary landscapes, most people dream.

But there’s a small subset of the population who claims either to have stopped dreaming, or never to have dreamed at all. A group of researchers recently decided to look into the sleep patterns of self-proclaimed non-dreamers, to try to determine whether they may still be producing dreams.
The researchers, whose study was published in the Journal of Sleep Research  recruited a unique group of participants. They wanted to look specifically at people who have REM sleep behavior disorder—a condition that causes people to act out their dreams. Because people with the disorder move around or speak in their sleep, their sleep patterns and behaviors are easier for scientists to observe.

According to New York Magazine, four percent of the participants in the 289 person study said they never dreamed or hadn’t dreamed in over a decade. However, upon observation, many of them appeared to dream, moving, speaking, or reenacting imaginary scenarios in their sleep. For example, one participant in his 70s, who claimed not to have dreamed since his 20s, was observed arguing with, punching, and swearing at an invisible enemy as he slept. Upon waking, however, he claimed not to have had any dreams.

The researchers recognize that the appearance of dream behavior is not definitive proof of dream production. More research is still needed to determine whether behaviors like sleep-talking and moving correspond to actual mental images. Still, the study provides strong initial evidence that non-dreamers may, in fact, be dreaming. 

This is an interesting study to apply to the sideways world when the characters "forgot" about all their time on the island.

If alleged "non-dreamers" dream but don't remember their dreams, does that not fit the pattern or premise of the sideways world? The characters had to be "jolted" into remembering their past. For Jack, it was touching his father's coffin. 

So if we transpose this scientific observation into the LOST story line, we get this possible explanation.

We know that the sideways world was the after life because Christian told Jack that everyone in teh church was dead.

Being dead, the characters could not "remember" their island time or the other characters.

Now, there would be two possible explanations of this: 1) the dead souls don't have clear recall of their past lives or 2) the dead souls can vividly dream (and probably collectively).

Now, many other researchers have been studying the purpose of dreams. Some believe it is a way humans try to solve real life problems in a safe and secure fashion. Some believe that dreams are a way for the body to rest and recharge (but the mind has to always be active since it controls all bodily functions). 

Why would the dead need to dream?

Perhaps, the same way the living do: in order to sort through their problems, anxieties, fears, and regrets in order to become self-aware, self-assured and self-healed in order to "move on."

Whether in work or relationships, some people do get bogged down to the point of being unhappily stuck in a situation or hurt from a missed opportunity. This paralysis can be long lasting and bitter.

The dead LOST souls needed a means of reviewing the errors in the lives, making peace with the choices that they made in life, and accept who they were in order to move on in the afterlife.

So it is possible, despite the similar living issues and problems the characters had, each of them were also "non-dreamers" who could not remember working out their issues in their own minds.