(CNN) — If you thought living through the pandemic was a waking nightmare, just imagine what it’s been like in dreams.

Many of us experienced vivid, frightening nightmares throughout the worst of the pandemic. Depending on our level of trauma — the loss of a loved one or being a health care worker on front lines of Covid-19-packed intensive care units — the bad dreams could be excruciating.

Psychologist Deirdre Barrett has been collecting our dreams and nightmares since the virus shut down our lives. Many of our night visions revolved around the fear of death, as our subconscious ruminated on the very real threat of Covid-19. Other dreams cast the virus as an invasive predator, often an insect.

“There were grasshoppers with vampire fangs, masses of wiggling worms, swarms of flying bugs which could be bees or flies or hornets,and armies of cockroaches racing at the dreamer,” said Barrett, an assistant professor of psychology at Harvard Medical School who has authored and edited numerous books on dreams, including Pandemic Dreams.

Women were especially hard-hit, Barrett found. One dreamer wandered “into a mortuary which she gradually discovers is embalming live COVID patients,” Barrett wrote in a paper published on the topic.

Barrett is continuing to follow pandemic dreams. She has collected from at least 76 countries more than 14,000 dreams, two-thirds of which are from the United States. In her ongoing analysis of the data, she has seen a change in the content of our dreams since vaccinations began and states and local communities have begun to reopen.

CNN spoke to her about the types of nightmares we’ve had during the pandemic and how they have evolved over time. The conversation has been lightly edited for clarity.

CNN: How can dreams provide insights into our lives during the pandemic?

Deirdre Barrett: Dreaming is just thinking in a really different brain state. There’s a lot of research on what’s called the consistency hypothesis of dreams, which has been pretty well proven: The more somebody thinks about certain topics by day, the more it’s going to turn up in their dreams at night.

But in the brain state we’re in during dreaming, visual areas are very active, the areas that tell stories are active and emotional areas are active, whereas verbal areas and logic are less active than usual.

We’re thinking about all of our usual thoughts and concerns, but we’re thinking about them in very vivid, visual, narrative or storytelling ways. Dreams may be more emotional, less logical, but the basic content still maps on very closely.

CNN: Why did you start collecting dreams from the pandemic?

Barrett: In addition to my work on dreams and how they contribute to creativity and objective problem solving, I’ve done several studies on dreams during crises or traumas. I did a survey of dreams after 9/11 and dreams in Kuwait during the first Gulf War, both during the occupation and shortly after. And I stumbled upon an archive of 500 dreams from prisoners of war in a Nazi POW camp in World War II that no one had examined.

It just seemed it would be interesting to see how the dreams during the pandemic resembled past crises. I put a global survey up on March 23, 2020, and there were some nightmares I saw from the start in other parts of the world that only turned up in the US later.

For example, in Italy where the virus hit early and hard, health care professionals were having these classic post-traumatic dreams in which someone was dying in front of them, and they thought it was their responsibility to save them and they couldn’t. I didn’t see any of those in the US for another two to three weeks, when cases in New York City started to climb.

Dreams like “Oops, I don’t have my mask on” or “Other people won’t wear their masks and I’m in danger” — I saw those from Asia right at the start, but they didn’t begin in the US until health care professionals told us to begin wearing masks.

I saw very similar dreams everywhere around the world, but for the most part the timing matched when the Covid-19 outbreaks were the worst in that region or when guidelines to the public changed.

CNN: How have our dreams changed this year compared to 2020?

Barrett: As the world began to open, there have been some fairly large changes in the proportion of dreams that people are reporting. For starters, I started seeing more positive, optimistic dreams.

These upbeat dreams tend to be about being back in some big, crowded social situation doing a favorite activity, such as dancing at a nightclub or being at a sporting event or being at family reunion with lots of family that actually live all over the country.

Dreams like that were pretty rare in the early weeks of the pandemic, and when people did dream like that they tended to remark that they woke up and felt this wave of sadness. They felt as if the dream had been taunting them with something that they could no longer do — like they were seeing something from their past that was not in their foreseeable future.

But beginning mid-December of 2020, when it was announced the vaccines were highly effective and were being given emergency use approval, positive dreams started increasing.

It was also really striking that the dream could be the same as from earlier months of the pandemic, but now people said they woke up happy. The dream had cheered them up because they felt their dream was foretelling a future in which everything was going to go well.

CNN: You mentioned in your paper that women carried the brunt of nightmares during the pandemic. Why?

Barrett: When I began the study on pandemic dreams, I predicted an increase in negative emotions and references to illness, death and the physical body. I compared the dream data I got to a huge pool of dreams that had been collected during a quiet time before the pandemic.

What I found was that both men and women’s pandemic dreams had two and a half times greater anxiety, twice the reference to illness, and four times the reference to death than dreams captured before the pandemic.

But it was only for women that the other negative emotions like sadness and anger were were elevated. They were almost twice as high for women, but men’s dreams showed no more anger or sadness than before.

I was a little surprised when I first got that result, but when I read the dreams more closely I found that bad dreams about homeschooling were almost all from mothers, rather than fathers, and there were many female dreams about how to take care of children or how to nurse sick people.

Another category that was elevated one and ahalf times in women were mentions of body parts, such as fingers, hands, arms, toes, feet, legs torso, breasts and genitals.

I thought that would be connected to illness, but often the dream would be “roommate is looking at this or that body part.” And I realized there’s been increased reports of domestic abuse and sexual violence in the home during the pandemic and an increase of unwanted sexual approaches from platonic roommates. So it seemed the dreams were reflecting problems that may be unique or more often experienced by women.

CNN: Are any dream topics reported during the pandemic continuing?

Barrett: People have continued to dream about masks — it’s a commonly reported dream — but there’s a subtle change. In the early days, it was always a fearful dream.

“I forgot my mask” or “My mask fell off” or “My mask is disintegrating in some magical way” — those were about half of the mask dreams. The other half were: “I’m around other people who don’t have a mask;” or “They don’t have it on properly;” or “Their mask has holes in it.”

In those early pandemic mask dreams, the dreamer would panic, and struggle to get further away from people because they were afraid of catching Covid-19. Definitely fear was the the main emotion.

By early last fall, however, instead of fear and contagion being the issue when the dreamer realized that they didn’t have a mask on, it would be shame or social embarrassment or “What will people think of me that I’m not wearing a mask?”

Those fall into a more traditional dream metaphor of social shame, when people are out in a mall and suddenly realize they have forgotten their clothing. It really looks to me like these mask dreams have temporarily replaced the “naked in public” dream that lots of people have.

That’s been a really interesting change, and I will be curious to see how long it lasts.

CNN: Based on your knowledge of trauma and nightmares, what do you expect to happen to pandemic dreams?

Barrett: What we know is that when people experienced the same traumatic event, many will dream about it shortly after it happens. Then, if you’re looking at the group average, it drops off over time and dreams about the event just disappear for more than half the people.

Doctors don’t diagnose post traumatic stress disorder (PTSD) until it’s been going on a certain amount of time, and it’s not considered a disorder to have the heightened startle response or daytime flashbacks or nightmares if they happen in the immediate aftermath. It’s a very normal post-trauma response to have nightmares about the event for a little while, and then most people adapt.

However, some people will continue to struggle and possibly develop long-termtrauma dreams, such as people that are most directly affected by the event and suffered severe trauma. That group also includes people who already have anxiety disorders and people who have suffered some earlier trauma in their history.

After 9/11, people who had the worst nightmares were in the building and barely got out, the first responders, and people who worked close enough to see scenes of bodies falling. Many of the worst nightmares I’ve received during the pandemic are from nurses and doctors on the front lines.

Other people can also developed long-term trauma dreams, such as people who were badly abused as a child, women who have been raped and combat veterans. This happens even in people who have not been continuing to have recurring nightmares about the earlier trauma.

A new trauma, even one experienced secondhand, comes along and gets a lot of news attention and that can activate dreams about the early trauma or the recent one, or even a hybrid of both traumas in the same nightmare.

I would say its going to be people who had the most direct experience with death and dying, those who are physiologically vulnerable to anxiety, stress and trauma, and those who have had prior trauma who are likely to have the longest struggle with nightmares.

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