A fear of the dark may trigger some insomnia, according to researchers at Ryerson University. The findings will be presented at Sleep 2012, the annual meeting of the Associated Professional Sleep Societies, in Boston.
In the small study of 93 college-aged men and women, researchers found that more poor sleepers than good sleepers confessed a fear of the dark.
“I think the most surprising part of the study is that people told us,” says researcher Colleen Carney, Ph.D., associate professor of psychology at Ryerson University, Toronto. Fear of the dark was confirmed through sleep lab experiments.
Carney and her research team decided to pursue the fear of the dark notion after she heard many people with insomnia, over the years, talk about sleeping with a light or TV on.
All participants (average age 22) completed questionnaires regarding their sleep habits. One particular questionnaire is called the Insomnia Severity Index that helps classify people as good or poor sleepers. Participants were then assigned into either the poor-sleeper group or the good-sleeper group—there were 42 poor sleepers and 51 good sleepers.
Interestingly, of the 42 poor sleepers, almost half said they were afraid of the dark. Of the 51 good sleepers, only about one-quarter were afraid of the dark.
In the sleep lab, Carney tried to confirm the fear of the dark. Four different times, she exposed both the good and poor sleepers to a burst of white noise.
“If you are nervous, you are going to flinch,” said Carney.
Researchers observed participants’ responses, such as blinking speed and other reactions to measure the level of fear. They were measured twice in a simulated bedroom setting that was lit and twice in the same setting while dark.
“We measured the blinks, the size, and how fast,” Carney said. ”The poor sleepers tended to blink fast in the dark in response to the unexpected noise.”
The poor sleepers had greater ”startle” responses only in the dark, she found, while the good sleepers tended to get used to the burst of white noise.
“That’s what you do when you aren’t afraid,” she said. “The poor sleepers actually became more afraid.”
Carney believes that, for the poor sleepers, a fear of the dark may contribute to increased arousal once the lights are turned off. To lessen insomnia, Carney says those who have a fear of the dark should work directly on the fear, or phobia.
Source: Ryerson University