Neuroscientists are trying to find out what happens to our brains when we dream or have nightmares

Scientists are exploring what happens in the brain during dreams and nightmares.

In a three-year research programme, neuroscientists at the Pennsylvania State University in the United States will study the brains of mice using advanced imaging techniques to better understand the neural mechanisms of nightmares and their links to anxiety-related mental health disorders, such as post-traumatic stress disorder (PTSD).

Scientists believe that every animal dreams, but experts don’t agree on why it happens.

“We don't actually know what nightmares are,” said Patrick Drew, a professor of engineering, science and mechanics at the Pennsylvania State University.

“We know that they occur during rapid eye movement sleep, and they probably involve sort of our overall brain circuit of fear. But nobody actually knows what's happening during a nightmare,” Drew added.

Dreams and nightmares are natural, and humans are not the only animals to have them. Typically, people have one to two dozen nightmares a year, according to the researchers.

“If we know what the optimal state of your brain is, what healthy happiness looks like, what healthy dreaming looks like… that can help us inform and solve what is gone awry in various disorders and diseases that might have components disrupted, like with sleep, like things like Alzheimer's disease,” Drew said.

As part of the research, mice will be treated with a drug called mefloquine for two weeks while being closely monitored for unusual behaviours.

Mefloquine is a malaria drug that is no longer prescribed because of its serious neurological side effects, including vivid nightmares.

Researchers will observe changes in pupil size to determine which stage of sleep the mice are in, including rapid eye movement (REM) and non-REM stages. Most vivid dreams occur during REM sleep, and people are more likely to remember them if they wake during this phase.

To map the mice’s facial expressions, researchers will use brain imaging techniques such as functional magnetic resonance imaging (fMRI), which measures blood flow to identify which areas of the brain are active, and calcium signal recording, a method that tracks changes in calcium levels within neurons to show when brain cells are firing.

Together, these tools will help identify specific neuron types that may play a role in dreaming.

They will also look at how two key areas of the brain, the prefrontal cortex, which helps control emotions, and the amygdala, which processes fear, change during nightmares.

The researchers aim to develop a model, based on mouse studies, to predict when mental health problems such as anxiety might develop, depending on the presence or absence of nightmares.

If successful, their findings could lead to new sleep-based treatments for people living with these conditions, the team said in a statement.

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