Narcoleptics Can Have a Hard Time Telling Dreams From Reality

If you have a jarring dream that you lost your job, you probably wake up feeling a sense of relief—it was just a dream! You get on with your day, and you go to that job you still have. But what if you remembered your job loss not as a figment of your imagination, but as reality? Instead of feeling relief, you would wake up distressed about being unemployed.

I was tipped off to this idea of dream-reality confusion by a Facebook friend who posted that she was having trouble distinguishing between the two. Someone commented that their dreams "are so realistic they feel like memories later," another that they'll dream about waking up and making a sandwich and "have no way of knowing if it was dream or reality," and another that it's "literally what most of [her] art is about."

It's normal to sometimes question whether or not you actually had that conversation, or wonder if you really ate that midnight snack. "People think they're awake when they're dreaming, so wake-dream confusion is universal," says Allan Hobson, a dream researcher and professor in the division of sleep medicine at Harvard Medical School. "But some conditions are probably more associated with thinking that a dream was real."

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It's common in people with psychotic disorders like bipolar disorder and schizophrenia, for whom delusions are a fact of everyday life. "The boundaries between cognitive states are blurry for these people," says Patrick McNamara, a neurology professor at Boston University. "Other studies have found they're often very creative individuals—because they can cross these cognitive boundaries, they're also more vulnerable to these confusion states."

This big problem may relate to a small section of your brain, a fold called the paracingulate sulcus. Studies show that people with a less pronounced fold experience more hallucinations and are worse at identifying imagined and real events. But dream-reality confusion disproportionately affects a particular group of nonpsychotic people: narcoleptics.

Erin Wamsley, a psychology professor at Furman University, led a study that found an overwhelming link between dream delusions and people with type 1 narcolepsy, the type accompanied by cataplexy, a complete and sudden muscle paralysis often brought on by strong emotions. Cataplexy is a split-second phenomenon—at one moment the person may be laughing at a joke, the next they collapse onto the floor. Once they drop, they often transition into sleep.

"It's thought that the fundamental problem in narcolepsy is that they're moving between states of consciousness too quickly and abruptly," Wamsley says. Eighty-three percent of narcoleptics interviewed for Wamsley's study experienced dream-reality confusion, almost all of them at least once a month. Only 15 percent of non-diagnosed people had the same problem, and only 5 percent experienced it more than once in their lives.

For narcoleptics, the confusion wasn't just more frequent, but also more drastic. As Wamsley reported:

Healthy people became "very briefly confused about a minor thing that's of no consequence" while "the narcolepsy patients were confused for longer periods of time about more serious things that a typical person would not be confused about," Wamsley says. It's worth noting that normal sleepers often face a dilemma—did that thing happen, or was it a dream?—while narcoleptics in Wamsley's study took their dreams for fact without question.

People with the sleep disorder have unusually vivid dreams and high dream recall, which may explain the error in their memories. "When you and I think about what is true and what is real, we might use perceptual vividness as a cue for that," Wamsley says. "Did you see something on TV or was it your real experience?" Narcoleptics might remember their dreams as real events because they're laden with IRL detail and clarity.

It's also possible that the hippocampus, the brain region responsible for encoding new memories, functions differently for them. Depending on your state of consciousness, your hippocampus is in one of two modes: It should record new memories in "write" mode when you're awake, and recap past memories in "playback" mode when you're asleep.

"When an organism falls asleep, memories of a recent experience are replayed in the sleeping brain on a cellular level," Wamsley says. But in narcolepsy, the hippocampus might stay in "write" mode during sleep, encoding dreams as real experiences as it would when you're awake. It's difficult to capture explanatory brain scans in a laboratory because dream-reality confusion doesn't happen on command. The question remains why it happens, but not if it happens.

"In narcolepsy patients, this was definitely something they were really suffering from," Wamsley says, even though it's not an official symptom of the disorder. "But there's very little research on this idea of confusing dreams versus reality." Future studies may test how well narcoleptics remember the source of a memory. "I would be interested in how they perform on a test like that to see if they have more general problems distinguishing what's real from what's imagined, or if it's really specific to dreams," Wamsley says.

For now, if you're just confused about inconsequential events, rest easy—it's okay if you ate that late-night sandwich.

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