Nightmares under the microscope

The dark, dreamy, nocturnal sphere can be very frightening, as anyone who’s had a nightmare can tell you. But how much do we actually know about nightmares? Katie Haylor asked Katja Valli - dreaming and sleep expert at the University of Skövde, Sweden and the University of Turku, Finland. First up, Katie asked Katja what we actually mean by the phrase nightmare...

Katja - My name is Katja Valli. I work at the University of Skövde, Sweden and the University of Turku, Finland. Nightmares are defined as emotionally negative dysphoric dreams that lead to an awakening from sleep.

Katie - And what is actually going on in the brain when we have a nightmare?

Katja - Nightmares typically emerge from rapid eye movement sleep which comprises about 20 to 25 percent of all sleep and this is more prominent towards the morning hours. In rapid eye movement sleep, our brains are highly active and especially the limbic areas, the emotional centres of the brain, the amygdala, are even more active than during wakefulness. And these emotional centres of the brain, their activity during REM sleep could easily correlate with the emotional content of dreams and especially the negative content of nightmares.

Another thing that happens during REM sleep is that the prefrontal areas of the brain where we have our rational thinking and logical reasoning but also emotion regulation, those areas are less active during rapid time and sleep than during wakefulness. So when the emotional centres are highly active these centres that help us regulate our emotions and especially our negative emotions, those centers are actually not active during REM sleep, suggesting that this is kind of like an emotion regulation problem are in nightmares.

Katie - And do we know why we get nightmares in the first place?

Katja- Nightmares can be roughly divided into two different types. One is idiopathic. They occur without any triggering event versus then post traumatic nightmares that occur after a person has been exposed to a stressful life-threatening event. But why nightmares overall occur as well as why do we have dreams in the first place, is still a mystery to science.

Katie - So who is most likely to get nightmares?

Katja - About 3 to 5 percent of the population have nightmares more than once a week and maybe about 30 to 40 percent have nightmares occasionally once a month or so. And factories that can affect having nightmares might be of course traumatic experiences that result in post-traumatic nightmares, stressful life situations, we might have personality traits that make us prone to get nightmares. People who are kind of open minded, trusting, more vulnerable, might more easily get nightmares than people who have harder boundaries.

Katie - And do factors like age and gender make a difference?

Katja - Age and gender both seem to make a difference in a sense that women typically report more nightmares than men especially in young adulthood. But in childhood there really isn't doesn't seem to be a sex difference between boys and girls. And by late adulthood, let's say by the age of 55 or 60 men have actually caught up with females on the frequency of nightmares. So especially young women reported are plenty of nightmares while young men the least nightmares.

Katie - So does that suggest that something's going on during puberty then if there's no difference in childhood?

Katja - That is a very good question. In fact in our group we have the hypothesized that sex hormones might have something to do with the frequency of nightmares. So higher levels of testosterone are typical for young men, might actually be protective of nightmares and the secretion of testosterone decreases with age in men. They actually start to get more nightmares. However there are some studies that have not found this increase in nightmares with age. So we still have to be careful about saying that age affects the frequency of nightmares.

Katie - Can having nightmares tell us something about a person's mental state generally?

Katja - If I would take a single nightmare from a single individual I wouldn't be able to say much about the person's mental or physical health, but if we look on the population level, people who report nightmares more often, they also have are more often depressive symptoms or other mental health problems such as anxiety disorders nightmares, also correlate to psychotic orders like schizophrenia. So on a population level there is a correlation but a single dream from a single individual really can’t be used to tell us anything about that particular individual’s mental health.

Katie - And what treatments are on offer?

卡佳为创伤后和特发性nightmares, there's a technique called imagery rehearsal therapy. It is relatively effective. The idea is to make a new version of the nightmare, so change the dream in any way the dreamer wants, write down the new version or tell the new version to a therapist, and then start practicing the new version in your imagination especially before bed time. And the idea here is that the nightmare has left a trace into our long term memory banks and we cannot erase that memory, but we can try to create a new competing memory that is more recent. Now when you fall asleep and the nightmare begins to evolve, what is activated from the memory banks is the new changed nightmare.

There are also other treatments such as trying to become lucid in the nightmare which means that when you are having a dream, you become aware that this is nothing but a dream and that you are actually sleeping safely in your own bed. But achieving lucidity is not an easy task for many people so that is why my first recommendation would be to try imagery rehearsal therapy.