Afraid of the Dark? You're Not Alone

Insomnia may be partly caused in some people by a fear of the dark

/ Author:  / Reviewed by: Robert Carlson, M.D

(RxWiki News) Being afraid of the dark isn't just a childish phobia. Many adults suffer from this phobia, and it may be an underlying factor contributing to insomnia.

The possible connection between being afraid of the dark and having difficulty sleeping is the primary finding of an unpublished study being presented at a conference on sleep.

"Talk to your doctor if your fear of the dark may be causing insomnia."

Lead author Taryn Moss and principal investigator Colleen Carney, PhD, both from the Department of Psychology at Ryerson University in Toronto, led a study to investigate whether a phobia of the dark might be linked with difficulty sleeping.

They enlisted 93 undergraduate students to fill out an insomnia assessment tool so the students could be split into groups of good sleepers and poor sleepers. Each student also filled out a questionnaire regarding fear of the dark.

Almost half of the total students said they were afraid of the dark, but the number with this phobia was almost twice as high among the poor sleepers. While 26 percent of the good sleepers had a fear of the dark, 46 percent of the poor sleepers did.

The students were then subjected to a test measuring their responses to startling noise in different lighting conditions. Wearing headphones, participants would hear sudden bursts of white noise, sometimes in the light and sometimes in darkness.

The researchers measured how much time passed before each person blinked at the loud noises in the different lighting environments.

They found that poor sleepers blinked faster at the noise while in the dark for the second time whereas good sleepers took longer to blink in the dark the second time when they had become accustomed to the darkness.

By measuring the participants' startle reflex, the researchers determined the poor sleepers were not simply more awake than the good sleepers in the darkness.

"The poor sleepers were more easily startled in the dark compared with the good sleepers," said Taryn Moss, the study's lead author. "As treatment providers, we assume that poor sleepers become tense when the lights go out because they associate the bed with being unable to sleep."Now we're wondering how many people actually have an active and untreated phobia."

The researchers concluded, "Fear of the dark may contribute to increased arousal once the lights are turned off at bedtime for this subset of poor sleepers."

Further studies are necessary to determine to what extend a fear of the dark might be a risk factor for insomnia and whether the phobia should be treated, they wrote.

The study was presented June 11 at the 26th annual meeting of the Associated Professional Sleep Societies in Boston. Because the study has not yet been published in a peer-reviewed journal, its results should be regarded as preliminary and still require review by researchers in the field.

The research was funded by the National Institutes of Health. No conflicts of interest were noted.

Reviewed by: 
Review Date: 
June 8, 2012
Last Updated:
October 22, 2012