A new trial tests imagery rehearsal for people with narcolepsy

For many people with narcolepsy, nightmares are one of the hardest parts of the condition, yet treatment trials have rarely aimed at them. A new study at the University of Utah is one of the first to do so.

Narcolepsy and the dreaming brain

Narcolepsy is a rare brain condition linked to the loss or malfunction of orexin (hypocretin) cells in the hypothalamus. Alongside daytime sleepiness, and in type 1 cataplexy (sudden muscle weakness triggered by emotion), it often brings hallucinations, sleep paralysis and broken night sleep. REM sleep, the stage of the most vivid dreams, tends to arrive soon after falling asleep.^[1]

Many of these symptoms look like pieces of REM sleep turning up at the wrong moment: the stillness of REM while awake, or dream imagery at the edge of sleep. A 2024 commentary by the sleep psychologist Jennifer Mundt argues that nightmares in narcolepsy may come partly from the same REM disruption, and partly from the stress, low mood and anxiety that often travel with a long-term condition. Summarising earlier studies, it puts frequent nightmares at roughly 29% to 41.5% of people with narcolepsy, against about 4% to 5% of adults in general, and calls them a distinct type that deserves its own research.^[2]

Older studies point the same way. In a Prague clinic, nightmares were found in about a third of 118 people with narcolepsy.^[3] In a German interview study of 60 patients and 919 controls, people with narcolepsy reported far more nightmares and far more lucid dreams, and 70% of those who had lucid dreams said lucidity brought relief during a nightmare.^[4]

What the trial is testing

The trial is called DAWN (Decreasing Nightmares in Adults With Narcolepsy) and is led by Dr Mundt. According to its registry record:^[5]

• Who can join. Adults living in the United States with narcolepsy type 1 or 2 and nightmares at least once a week, whose sleep and psychiatric medicines have been stable for at least a month. People already in trauma- or sleep-focused therapy, who have had behavioural treatment for nightmares before, or who have untreated moderate to severe sleep apnoea are not eligible.
• The treatment. Imagery rehearsal therapy, also called cognitive behavioural therapy for nightmares: seven weekly sessions by video call.
• The design. Randomised, with a waiting list as the comparison. Everyone is treated; half start after the first assessment, half after the second. Romantic partners who live with a participant can also take part in the assessments, but not the treatment.
• What is measured. Nightmare severity on a standard questionnaire and nightmare counts in daily sleep diaries, at the start, at 10 weeks and at 19 weeks, with anxiety and depression as secondary measures.
• Size and timing. About 80 participants. It started on 1 July 2026, is recruiting, and is expected to finish in September 2027. The record lists a grant from the American Academy of Sleep Medicine Foundation.

What came before

Before DAWN, Mundt and colleagues ran a smaller pilot, published online in 2024. Six adults with narcolepsy and at least three nightmares a week had seven sessions of nightmare therapy adapted for narcolepsy; three also tried a technique designed to encourage lucid dreams. Nightmares fell from an average of 8.38 a week to 2.25 after treatment, severity improved, and participants described less shame and anxiety about sleep.^[6] With six people, that is a proof of concept, not proof.

Why it matters, and its limits

Imagery rehearsal is the treatment sleep medicine recommends for nightmare disorder,^[7] but most of the evidence comes from people without narcolepsy. Whether it works as well when nightmares are bound up with REM sleep that behaves differently is exactly the question.

DAWN is a pilot: about 80 people, no blinding, a waiting-list comparison rather than another treatment, and English speakers in the United States only. A positive result would justify a larger trial; it would not settle the matter on its own.

What this means for you

If you live with narcolepsy and nightmares, they are worth raising with your sleep team, even if they are not the symptom you were diagnosed for. Please don’t change any medicine on your own; talk to your doctor or pharmacist. You can read how imagery rehearsal works, and about sleep paralysis, the weight on your chest.