Four years ago, Samantha Torres woke to a blood-curdling scream coming from her 2-year-old’s bedroom. There she found her daughter, Annabelle, shouting about spiders with a glassy, detached look in her eyes. Terrified, and unable to comfort their daughter, Torres and her husband rushed Annabelle to the emergency room.

“I had no idea what was happening,” Torres said. “It was really, really traumatic.”

By the time the Claremont family arrived at Valley Regional Hospital, Annabelle was fine. The staff checked her out and sent the family home. Forty-five minutes after she fell back asleep, Annabelle was again screaming and glassy-eyed. This time, the panicked parents went to Dartmouth-Hitchcock Medical Center, where the nurses told them that Annabelle had been having a night terror.

Night terrors are fairly common in children, affecting about 1.5 million each year, but they are a sleep condition that many parents haven’t heard of unless they have experienced them personally.

During a night terror, children in deep sleep will act terrified and might even seem like they are hallucinating, according to the Night Terrors Resource Center, a website written by David Richards, who said he experienced night terrors for 20 years. Although most kids have their eyes open and are moving around during an episode, they’re actually still asleep.

“It’s scary to parents because the child looks awake but isn’t, and isn’t responsive,” said Dr. Tricia Groff, a pediatrician at the Children’s Hospital at Dartmouth-Hitchcock. “If you try to wake the child, it might make the child more distressed.”

At DHMC on that first night, Torres realized she had been doing everything wrong by trying to hold and comfort her daughter. Instead of intervening, it’s recommended that parents stay present to make sure that a child does not harm herself, but otherwise should let the night terror play out on its own.

“I try to reassure parents that night terrors are self-limited in nature,” Groff said.

Although the episodes will eventually end, they can last up to 30 minutes, which can make for a grueling night for parents. This is especially true for the parents of children who, like Annabelle, have experienced more than one terror in a single night. Such children are more likely to have repeat terrors.

“It made for very long nights,” Torres said. “Some nights my husband and I were just staring at each other, or I would just sit there and cry.”

Groff said that overtired children are more likely to experience night terrors and other sleep disturbances, so having established sleep routines and making sure that children are well-rested are important preventative measures.

“If children are sleep deprived these things tend to come up,” Groff said.

Eventually Torres found ways to soothe Annabelle a bit. She would agree with whatever Annabelle was saying in her sleep rather than arguing with her, even if her daughter’s proclamations made no sense. She also learned that if she encouraged her daughter to use the toilet it was often enough to wake Annabelle up and end the episode.

“We just figured out what works for our kiddo,” Torres said. “Every night terror is different and every kid is different.”

Fortunately, the night terrors were worse for Torres and her husband than they were for Annabelle.

“She never remembers them when she wakes up,” Torres said.

Children can experience night terrors from toddlerhood through puberty, Groff said. There seems to be a genetic component, although researchers aren’t sure why night terrors run in families.

Annabelle is now 6, and still experiences some sleep difficulties, although the night terrors occur less frequently. Torres also has a 2-year-old son who has not experienced the problem. However, she said that if her son does have night terrors the episodes will be much less terrifying for her and her husband now that they know what is happening. She hopes that more parents will learn about night terrors in order to avoid the unnecessary panic — and hospital visits — that she experienced.

“I just wish I had known what they were. It was really scary and really overwhelming,” Torres said. “Unless your kid is affected, you might not know what this is until the middle of the night when you’re panicking with your kid.”