The study involved 3,430 ethnic Chinese adults in Taiwan. They answered questions about lifestyle and sleep in 1990 – 1991.
They reported their habitual sleep duration. They also answered the question, “How frequent is your insomnia complaint?” The four response options ranged from “no insomnia” to “insomnia nearly every day.”
The median follow-up period was 15.9 years. Deaths were identified from official death certificates. Home visits also confirmed the deaths.
Results show that 901 participants died, and 420 developed heart disease. The relative risk of death for people who reported sleeping five hours or less was 15 percent higher than in those who slept seven hours. The risk of death was 34 percent higher in people who reported sleeping nine hours or more per night.
“Our data indicate that an optimal sleep duration (7-8 h) predicted fewer deaths,” the authors wrote.
People who reported having “insomnia nearly every day” had a risk of death that was 70 percent higher than those who had “no insomnia.” They also were 78 percent more likely to have had a heart disease event during the follow-up period.
Combining sleep duration with insomnia also revealed elevated risks for “long sleepers.” The risk of death was 2.5 times higher in people with frequent insomnia who reported sleeping nine hours or more. They also were twice as likely to have had a heart disease event.
“This finding may reflect ‘nonrefreshing sleep’ for reasons other than insomnia, such as sleep apnea” wrote the authors.
A study presented at SLEEP 2009 linked mortality risk to insomnia with short sleep duration. That research team also has found that insomnia with short sleep time is a significant risk factor for hypertension and diabetes.
Read more about insomnia.
Image by Brent Ho