A new study of dream patterns in narcolepsy patients may provide new hints at what the sleep disorder is doing to patients’ brains. A better understanding of the way narcolepsy affects a patient’s dreams could lead researchers to a more thorough understanding of the disorder’s neurological mechanisms. That, in turn, could lead to the development of more effective treatments.
REM Sleep, Dreams, and Narcolepsy
When we fall asleep, we normally move through several stages of sleep during which our brain is not very active. After an hour or two, we usually fall into a type of sleep called REM sleep (so-called because our closed eyes tend to move around rapidly during this stage). During REM sleep, our brain is very active. A normal sleep pattern has us cycling between non-REM and REM sleep throughout the night.
The sleep disorder narcolepsy is characterized by extreme daytime sleepiness and the tendency to fall asleep quickly and often even during the daytime. During these brief daytime sleep episodes, patients often fall into REM sleep much more quickly than normal, sometimes within minutes after falling asleep. These unusual periods are called sleep-onset REM periods (SOREMPs).
Normal REM periods are the times when we tend to dream most vividly. During non-REM sleep, we’re more likely to not dream at all or to have the feeling that we’ve dreamed without being able to recall the dream’s details (a phenomenon referred to as a “white dream”).
Scientists have wondered just how closely SOREMPs resemble normal REM sleep periods, and that’s where dream studies hope to provide answers. Do narcolepsy patients dream during SOREMPS, and if so, how vivid are the dreams?
Dream Stories and Narcolepsy
The study conducted at the University of Bologna examined the dream patterns of narcolepsy patients. Thirty participants were put through a standard exam called a Multiple Sleep Latency Test (MSLT). In the MSLT, patients take a series of short naps spaced about two hours apart. Some of the participants were also studied during nighttime sleep.
After their sleep periods, patients were asked for detailed reports about their dream experiences. Researchers then compared the dream experiences between periods of non-REM sleep, SOREMPs, and nighttime REM sleep.
The study found that participants reported vivid dreams with a strong story-like narrative structure during about 75% of their SOREMP naps. They experienced such vivid dreams only about 25% of the time during naps with only non-REM sleep. The SOREMP dreams were relatively long and complex, with recalled details and a structured series of events, a pattern that was similar to dreams during nighttime REM sleep.
The study results suggest that patients’ brains are cognitively active during SOREMPs. They are experiencing an ordered thought process, and they are recording memories of their dreams that they can recall later. This pattern more closely resembles REM sleep than it does non-REM sleep, during which the brain is much less active and its memory centers are less likely to process a dream experience.
Identifying similarities in dream structure between SOREMPs and REM sleep periods is only a small piece of narcolepsy neurophysiology puzzle. Every new piece discovered, however, could move researchers toward new therapies and treatments for the disorder.