麻豆传媒

The earliest dream Chris could remember was one that haunted his mind for months during preschool. In it, he watched family members and pets melting during a house fire. They turned into 鈥渟everal humongous blobs that resembled bubbling pizza topping鈥�, each containing fragments of their body parts. More than 25 years later, the images still haunt him.

For Jess, nightmares marked a difficult time in her late teens when she was struggling with anxiety. 鈥淚 would sometimes miss weeks of school because of my nightmares,鈥� she now recalls, several years later. 鈥淚 couldn鈥檛 sleep, I couldn鈥檛 function.鈥� Jess remembers nights spent half awake, falling in and out of a recurring nightmare where she was unable to scream or move, engulfed by paralysing fear. Even after waking, she couldn鈥檛 escape the feeling of helplessness.

Chris and Jess both responded to a 鈥淕et Paid to Nap!鈥� advert inviting people who had at least two nightmares a week to take part in a research study. Early one morning in late 2014, they arrived at my workplace 鈥� the in the Center for Advanced Research in Sleep Medicine in Montreal, Canada. They and other volunteers ran through questionnaires, tests of creativity and reported their waking daydreams before we pasted electrodes to their scalps and bodies and finally asked them to take a nap.

What we and other labs have found is casting nightmares in a new light. Horrific as having them frequently can be, it also seems to endow more regular positive dreams, and heighten empathy and creativity. These discoveries are challenging not only our understanding of what causes nightmares, but also how we should treat them.

Until very recently, research into nightmares has mainly focused on the negatives and the distress they cause. They became classified as a mental disorder called 鈥渄ream anxiety attack鈥� in 1980. Over the past few decades, the definition of nightmares has evolved to refer more generally to any intense negative dream that awakens the dreamer and is vividly recalled on awakening. Most are characterised by fear, but they can feature sadness, anger or any other negative emotion.

鈥淧eople who have frequent nightmares may be more empathetic when awake鈥�

There are two main theories about what causes recurring nightmares. Clinical research shows that nightmares are often related to a history of abuse or neglect, leading to the idea that nightmares develop in response to an 鈥渁ccumulation of adverse events throughout life鈥�, says , director of my lab and co-author of the most recent diagnostic criteria for nightmare disorder (see 鈥�When nightmares get serious鈥�, overleaf). Nielsen considers nightmares to be a disturbance in one of the normal functions of dreaming: to help people to deal with emotional experiences. The excessive fear and emotion in a nightmare wakes you before the dream can do its job. This is similar to the view of nightmares in post-traumatic stress disorder 鈥� when a traumatic memory is too strongly emotional, it repeatedly replays in dreams and cannot be overcome.

The other suggestion is that nightmares serve an evolutionary function by forcing the brain to re-enact adverse events during sleep so as to better prepare people to deal with them next time; an idea known as threat simulation theory. , who researches dreaming at the University of Turku in Finland, says nightmares are the 鈥渦ltimate expression鈥� of threat simulation, forcing us to attempt to escape or defend ourselves.

Although these nightmares usually happen late at night, our team was interested to find out whether people who have frequent nightmares have intensely negative dreams and thoughts during the day as well. And if so, whether this persistent negativity interferes with other waking functions. Understanding this could help us work out which theory about the cause of nightmares makes more sense 鈥� do they interfere with normal activity or serve a functional purpose?

In the hope of capturing some daymares in the lab, we hooked up Chris, Jess and 12 other volunteers to a montage of electrodes before they took a nap. Electrodes on the scalp measured brain activity, allowing us to determine sleep stages, particularly rapid eye movement (REM) sleep 鈥� the state when dreaming is most vivid. Other electrodes measured heart rate and muscle tension, including two above the right eyebrow 鈥� if you notice someone frowning or scrunching their face as they sleep, they are likely in the throes of a nightmare.

Once the electrodes were set, the volunteers were ready to star in their very own film noir, a 90-minute biography of their sleeping selves, filmed through an infrared camera and projected onto a TV in the control room. The sleep technicians watched as the subjects slipped into sleep, waiting for the distinct flitting eye movements that mark the onset of REM sleep, as the eyes scan the dream world. After 10 minutes of REM, a 鈥渂eep鈥� roused the dreamers and they groggily propped themselves up to recount their adventures.

Neither Chris nor Jess had a nightmare. In fact, no one in their group did. This was initially disappointing, but not unexpected; nightmares are notoriously difficult to catch in the lab. Even so, all 14 did recall a dream.

It turns out that people who have a lot of nightmares also have an unusually high number of good dreams. Our volunteers averaged about two nightmares per week, but they also . At the time of the study, Chris was recalling eight dreams a week; of these, only two were nightmares. In comparison, the average dream recall frequency for someone of his age 鈥� 32 鈥� is two or three dreams per week, with less than one per month being a nightmare.

The impact of good dreams is more than a fuzzy feeling on waking. In one of his positive dreams, Chris remembers taking part in a protest and protecting fellow activists from the police. Even though he鈥檇 never been part of this kind of group in real life, he said the dream left him feeling 鈥渞efreshed and optimistic鈥�. My colleagues and I think it is possible that positive dreams spill over and enhance waking life in a manner analogous to how nightmares cause distress on waking.

For instance, some research suggests that social dreams enhance feelings of closeness in the real world. In fact, this has recently been proposed as an evolutionary function of positive dreams, parallel to the evolutionary function of threat simulation in bad dreams. The new of dreaming suggests that positive interactions in dreams encourage social behaviours and strengthen personal relationships. 鈥淲e only get better at things we practise for,鈥� says Valli, 鈥渟o if the function of dreaming is to facilitate social skills, dream simulations should focus on the positive aspects of social life: social bonding, bond strengthening, prosociality, and so on.鈥�

We were expecting the waking hours of people who have a lot of nightmares to be dominated by the negativity of their visions, but in fact their many pleasant dreams may make them feel even more connected with others.

There are hints that those who have frequent nightmares may be more empathetic too. At least one recent study has found that those prone to nightmares the actions or emotional expressions of others. Such mirroring enables us to understand another person鈥檚 perspective and feel what they feel, and is essential to developing relationships.

It is not clear whether this kind of emotional fine-tuning is a cause or consequence of frequent nightmares. It could be both. Sleep researcher Ernest Hartmann, while a psychiatrist at Tufts University School of Medicine in Boston in the 1980s, found that people seeking therapy for nightmares were not necessarily more fearful or anxious, but rather had a general sensitivity to all emotional experience. He concluded that sensitivity is the driving force behind intense dreams. Heightened sensitivity to threats or fear during the day results in bad dreams and nightmares, whereas heightened passion or excitement may result in more intense positive dreams. And both these forms of dreams may feed back into waking life, perhaps increasing distress after nightmares, or promoting social bonds and empathy after positive dreams.

The effects go further still. Hartmann realised that this sensitivity spills over into perceptions and thoughts: people who have a lot of nightmares experience a dreamlike quality to their waking thoughts. And this kind of thinking seems to give them a creative edge. For instance, studies show that such people tend to have and . Jess and Chris scored highly on a test to measure this, called the , and both are artists: Jess is a painter and photographer, Chris a musician.

To further explore this creativity, we asked our volunteers to do a word-association task. We presented them with one word at a time and asked them to come up with three meaningfully associated words. Responses were scored by how common they were. For example, the three most common responses to the word 鈥減anic鈥� are 鈥渁ttack鈥�, 鈥渟cared鈥� and 鈥渇ear鈥�. However, people with frequent nightmares than a control group, suggesting that they think outside the box and make broader associations between concepts, which are thought to be essential to creative thought.

So the evidence points towards the idea that, rather than interfering with normal activity, people who are unfortunate in having a lot of nightmares also have a dreaming life that is at least as creative, positive and vivid as it can be distressing and terrifying. What鈥檚 more, this imaginative richness is unlikely to be confined to sleep, but also permeates waking thought and daydreams.

That鈥檚 not to say we should all be wishing for more nightmares. They can be overwhelming, especially when they become more frequent and out-of-control during periods of stress. They may also dredge up remnants of past trauma or abuse, and in these cases, the distress may vastly outweigh any advantages. Jess is clear on this point. 鈥淚f I could take a medication that got rid of my nightmares, I would,鈥� she says.

A drug might not be necessary, though. Perhaps most importantly, these new findings challenge how we go about treating nightmares. Instead of focusing on abolishing negative dreams, or the memories of the trauma that caused them, there might be ways to help people control their dreams and nightmares, without losing the benefits.

One problem is that nightmares awaken the dreamer before the brain鈥檚 simulation scenario is complete. 鈥淪o, in nightmares, it is not always possible to rehearse happy endings, or even to successfully respond to the threat,鈥� says Valli. Imagery rehearsal therapy is a waking visualisation technique designed to help people modify their nightmares and direct them towards a more positive outcome. The person writes down their nightmare and decides on a more desirable ending. They then visualise and mentally play out this finale several times before they sleep. Perhaps capitalising on the vivid imagination of nightmare sufferers, the therapy has been found to and associated distress.

鈥淓ven video games can protect dreamers from distress during nightmares鈥�

Another idea is that people could take control while they sleep. Although lucid dreams, where people consciously control what鈥檚 going on in the dream world, are rare in the general population, they can be . Jess has lucid dreams almost every day. She uses this dream space to work on art projects, especially if she is struggling to finish something in her waking hours. 鈥淚鈥檒l try to move things around in the dream to play with ideas for a painting or compose a photograph,鈥� she says, and often on awakening the process proves successful.

Dream come true

While lucid dream induction is difficult, it is a learnable skill, and one that nightmare sufferers may be naturally adept at. Training is similar to imagery rehearsal therapy, but practising alternative endings should continue within the lucid dream state. One recent study found that such training . It also increases recall of more positive dreams and leaves dreamers with a generally more positive attitude and a decreased fear of dreaming.

Even video games can work as a from distress. For instance, research shows that soldiers who regularly play video games involving war and combat say they have less violent dreams and less of a sense of helplessness than soldiers who don鈥檛 play the games. 鈥淕amers report more dream control than any other groups,鈥� says , who is spearheading the work at MacEwan University in Edmonton, Canada. 鈥淚f you鈥檙e having fun in the tension around playing a combat-centric game, it makes sense that threat and thus fighting back or combat in dreams would also be fun.鈥�

These approaches might not work for everyone, because there are differences between the nightmares focusing on specific events had by people with post-traumatic stress disorder and the theme-based imagery common to most nightmare sufferers. But even understanding that these kinds of nightmares are different could help those who want to hang on to the creative and social benefits of nightmares while freeing themselves from the distress 鈥� something Chris is trying to teach himself to do. 鈥淚鈥檝e grown to have a happy indifference towards my nightmares,鈥� he says. 鈥淭hey鈥檙e just something to laugh at.鈥�

This article appeared in print under the headline 鈥淭he upside of nightmares鈥�