June 11, 2012 -- Insomnia in some adults may be driven by a fear of the dark, Canadian researchers say.
In their small study of 93 college men and women, Ryerson University researchers found 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, PhD, associate professor of psychology at Ryerson University, Toronto.
She and her team confirmed participants were afraid of the dark during sleep lab experiments.
Insomnia can include difficulty falling or staying asleep, waking up too early, or having poor-quality sleep.
It can occur as a side effect of medications such as antidepressants, allergy drugs, or stimulant drugs used for such conditions as ADHD. It is more common with age and among women, according to the National Sleep Foundation.
Carney and her colleagues decided to focus on fear of the dark after she heard many people with insomnia, over the years, talk about sleeping with a light or TV on.
Insomnia, Fear of Dark Study Details
The researchers asked all 93 men and women, average age 22, to complete questionnaires about sleep habits.
One is called the Insomnia Severity Index. It helps classify people as poor or good sleepers.
They then assigned them to a poor-sleeper group or a good-sleeper group. There were 42 poor sleepers and 51 good sleepers.
Of the 42 poor sleepers, almost half said they were afraid of the dark.
Of the 51 good sleepers, just about one-quarter were afraid of the dark.
In the sleep lab, Carney tried to confirm the fear of the dark. She exposed both the good and poor sleepers, four different times, to a burst of white noise.
"If you are nervous, you are going to flinch," Carney tells WebMD.