and reported daytime sleepiness represent a subpopulation at specific risk, according to an analysis of a 5-year population sample. The new was published online in Sleep and led by Charles Morin, PhD, of Laval University, Quebec City.
The risks of daytime sleepiness and MVA are generally thought of in the context of obstructive sleep apnea (OSA) or men, but the results of the new work suggest that insomnia should not be overlooked, according to Krishna Sundar, MD, clinical professor of pulmonary, critical care, and sleep medicine, and medical director of the Sleep-Wake Center, at the University of Utah, Salt Lake City.
“The notion has been that it may keep them more hypervigilant and less prone to motor vehicle accidents because they are less able to fall asleep even if they want to during the daytime, as compared to other conditions like sleep apnea where there is a higher tendency to doze off,” Dr. Sundar said in an interview.
It should also be remembered that patients aren’t always completely reliable when it comes to self-assessment, according to Brandon M. Seay, MD, a pediatric pulmonologist and sleep specialist at Children’s Healthcare of Atlanta. “Most people with insomnia won’t say they are sleepy in the daytime, but when you objectively look, you do see an element of daytime sleepiness even if it’s not perceived that well by insomnia patients,” said Dr. Seay.
The heightened risks in young women with insomnia is notable, according to Dr. Sundar. Insomnia is more common in women, and they may also be more susceptible to unintended consequences of sleep medications because they metabolize them more slowly. “Especially for younger women, if they are insomniac and on prescription medicines, and if they have excess daytime sleepiness, this [risk of MVA] needs to be factored in,” said Dr. Sundar.
Insomnia is a condition that waxes and wanes over time, and can vary in its presentation across age groups, which is why the authors chose to conduct a prospective longitudinal study in a Canadian sample. They recruited 3,413 adults with insomnia (median age, 49.0 years; range, 18-96; 61.5% female). After 5 years, the retention rate was 68.7%.
After filling out baseline information, participants were asked every 6 months about MVAs and what role they believed daytime consequences of insomnia played if an accident occurred. Prescription and over-the-counter medication use were also self-reported.
In the first 2 years of the study, 8.2% of women aged 18-29 reported MVAs, which was the highest of any demographic (range, 2.3%-4.3%). By the third year, the frequency in this group overlapped that of men in the same age group, and both remained higher than older age groups.
Participants judged that insomnia consequences played a role in 39.4% of reported MVA. In 17.2% of accidents, participants said insomnia consequences contributed at least 50% of the cause.
MVA risk was associated individually with presence of insomnia symptoms (hazard ratio [HR], 1.20; 95% confidence interval, 1.00-1.45) and daytime fatigue (HR, 1.21; 95% CI, 1.01-1.47), but there were only trends toward associations with sleeping fewer than 6 hours (P = .16) and excessive daytime sleepiness (P = .06). MVAs were associated with reported past-year use of prescribed sleep medications (HR, 1.50; 95% CI, 1.17-1.91) and reported use of OTC medications (HR, 1.42; 95% CI, 1.02-1.98).
In women aged 18-29, MVAs were associated with insomnia symptoms (HR, 1.83; 95% CI, 1.13-2.98) and excessive daytime sleepiness (HR, 2.42; 95% CI, 1.11-5.24).
The study was limited by its reliance on self-reporting and lack of data on specific medications used.
The study was funded by the Canadian Institutes of Health.