Can foods cause nightmares?
A fifth of us believe that , especially late at night, can cause disturbing and nightmarish dreams, according to research recently carried out by Tore Nielsen, director of the Dream and Nightmare Laboratory in Montreal, Canada, where I work. The most common culprits were foods containing dairy products, such as cheese, ice cream and pizza, and spicy dishes.
One explanation is that people are simply misattributing their bad dreams to food. But it is also reasonable to believe that these foods do influence dreams.
We know that what we eat can affect our mood and cognition during the day, so digesting these foods while sleeping might similarly impact dreams, perhaps making them more vivid or emotional. And it might be no coincidence that people point the finger at dairy products most often, because many people鈥檚 stomachs are sensitive to the lactose in them. So difficulty digesting foods, particularly when eaten late at night, may affect the dreaming mind, creating discomfort and negativity in dreams.
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What are the most typical nightmare themes and what do they mean?
Themes tend to vary by lifestyle and age. Perhaps unsurprisingly, students often have school-related nightmares, like missing or failing an exam. The variety is immense, though, from zombie apocalypses to teeth falling out. Some of the most common nightmares we see in the lab include being attacked or chased, dying, falling, or being paralysed. Even a mundane dream, however, like looking for your car keys, can stir up such severe anger or distress that it becomes a nightmare.
When these themes recur over several nights it is likely that there is some underlying stressor that needs resolving. Dreams and nightmares often symbolise and potentially exaggerate the underlying problem. For instance, an impending tidal wave is a common nightmare after a trauma; the wave probably reflects overwhelming feelings of helplessness and fear.
If the dream changes or disappears with time, that鈥檚 a good sign that the trauma has been confronted or the problem resolved. In some cases, recurrent nightmares may even be helpful. Students who have nightmares of failing an exam the night before actually . So even though the nightmare represents a waking-life stressor, it also suggests these students are more invested in succeeding.
Why are nightmares more common in children?
Many sleep disturbances are more common in children than in adults, and this is probably because the brains of children are still developing. Children often sleep-walk or have night terrors, which typically decrease after adolescence. Night terrors are different from nightmares 鈥� they can be very disturbing, especially for parents, because a child might bolt upright in bed screaming and crying, but have no recollection of the experience on waking, whereas people remember nightmares when they wake up.
Nightmares are probably also related to cognitive and emotional development, because children are learning how to become more independent and think and feel for themselves, which can be a frightening process. Dream researcher Patricia Garfield, author of , analysed 158 nightmares in children and found that almost half of them involved being chased. Others included sensing something scary, injury or death, losing something, and falling.
Garfield suggests that these themes . For instance, she says dreams of being chased are related to waking-life feelings of being under pressure; being paralysed represents feeling trapped; and accidents 鈥� such as a car crash 鈥� happen when children feel out of control.
Happily there are ways to help 鈥� one of the most effective ways to is to asking them to draw out happy endings to their nightmares (see 鈥�The upside of nightmares: How bad dreams are also good for you鈥�).
How do nightmares linked to post-traumatic stress disorder differ from normal nightmares?
People who have nightmares as a result of post-traumatic stress disorder (PTSD) describe them as being similar to flashbacks: remarkably vivid and emotional, intrusive memories, that feel as if they are happening right then and there. Flashback memories can be triggered by something that is associated with a trauma, but during sleep, almost any emotional dream might trigger a traumatic nightmare. Some people with PTSD have these nightmares more than five nights a week.
PTSD nightmares also replay the actual traumatic event, rather than a symbolic theme. For instance, war veterans often have nightmares that relate to experiences at the front, even decades after the war. As PTSD symptoms improve, or in milder cases, the nightmares become more 鈥渘ormal鈥� and symbolic. Treating nightmares is an important part of treating PTSD, and improvement in nightmare symptoms is actually related to .
Why do I have the same nightmare again and again?
Recurrent nightmare themes often start at a young age, but they can begin at any time and continue for many years. The theme of missing an exam, for instance, often begins at college when the stress of succeeding in school is most intense. Or a child might have a dream of being chased by a monster after being bullied at school.
The exam dream might then reappear many years later, say the night before a big meeting with your boss or before giving a presentation to clients. The stress and desire to succeed triggers the same dream, even though the waking-life circumstances have changed.
Similarly, a new monster 鈥� perhaps an aggressive boss or an overbearing mother-in-law might trigger the childhood nightmare of being chased. It鈥檚 a question of a new situation triggering the same emotions.
See also 鈥�The upside of nightmares: How bad dreams are also good for you鈥�
For more on sleep and dreaming, visit our sleep special
