Persistent insomnia linked to higher risk of death, study finds

Date: Feb-27-2015A new study that examines the link between insomnia and raised risk of premature death

concludes that persistent insomnia poses a greater risk than intermittent insomnia.

Acute insomnia can be due to anxiety about an important event.

While previous studies have already shown links between insomnia and increased risk of premature

death, they have not clarified whether the risk differs between persistent and intermittent

insomnia.

Intermittent or acute insomnia is of short duration and often linked to specific events - for

instance, not being able to fall asleep the night before an exam or an important job interview.

Persistent or chronic insomnia is a long-term pattern of disrupted sleep on several nights a week

that lasts for months and years and can be due to a number of causes, including shift working, poor

sleep habits and medication use.

In the US, around 20% of adults are affected by insomnia, half of whom suffer from

persistent insomnia.

For their study, researchers from the University of Arizona in Tucson sought to clarify if the

link between insomnia and raised risk of premature death depended on the type of insomnia. They also

looked at whether there was a difference in inflammation.

Knowing how persistence of insomnia affects risk of death might affect treatment decisions

The researchers had a hunch that the inability to get a good night's sleep that goes on for years

has a direct effect on the risk of death, regardless of the underlying reasons for it.

Lead

investigator Sairam Parthasarathy, associate professor of medicine at the University of Arizona

College of Medicine, explains:

"We hypothesized that insomnia that was persistent over 8 years, rather than

intermittent insomnia, was associated with death independent of the effects of sedatives, opportunity

for sleep (to distinguish it from sleep deprivation), and other confounding factors in a

representative sample of the general adult community.

An enhanced understanding of the association between persistence of insomnia and death would inform

treatment of the 'at-risk' population."

For their study, Prof. Parthasarathy - who is also director of the Center for Sleep Disorders at

the University of Arizona Medical Center - and colleagues examined data from 1,409 adults who took

part in the Tucson Epidemiological Study of Airway Obstructive Disease (TESAOD).

Participants were enrolled in 1972 and surveyed and examined until 1996. After that, deaths in the

group continued to be monitored until 2011, making a total study period of 38 years.

Persistent insomnia linked to 58% higher risk of death

The researchers were able to test cryopreserved blood samples that were collected at the start and

at intervals over the study period. The participants completed questionnaires about their sleep habits

twice - once between 1984 and 1985 and again between 1990 and 1992.

The team put the participants into one of three categories:

Persistent insomnia - insomnia was present in both questionnaires completed in 1984-1985 and 1990

-1992

Intermittent insomnia - insomnia was present in either but not both questionnaires

Never insomnia - insomnia was not present in either questionnaire.

When they analyzed the results, the researchers adjusted for factors that might influence any links

between insomnia and risk of death, such as age, sex, weight, smoking status, use of sleep

medication and exercise.

After taking the potential confounders into account, they found that participants with

persistent insomnia had a 58% higher chance of dying during the study than participants in the never

insomnia group.

The results also indicated that the excess deaths in the persistent insomnia group were due to

cardiopulmonary factors rather than cancer.

Inflammation levels also higher in persistent insomnia group

While members of the intermittent insomnia group appeared to have a higher risk of dying in the

study period than those of the never insomnia group, the researchers found this risk went away when

they adjusted for factors such as weight, smoking status and exercise.

From the blood sample analysis, the team also found that levels of C-reactive protein (CRP) - a

measure of inflammation that is also an independent risk factor for mortality - were higher in the

persistent insomnia group.

And when they adjusted the link between persistent insomnia and raised risk of death to

take into account CRP levels, the researchers found there was still a raised risk of death of 36% for

participants with persistent insomnia.

Meanwhile, as this study uncovers the risks associated with lack of sleep, Medical News

Today recently learned how too much sleep could increase the risk

of stroke. In the journal Neurology, researchers at the University of Cambridge in the UK

describe how they analyzed the sleeping habits and health of 9,000 people and concluded that sleeping

more than 8 hours a night was tied to a 46% increased risk of stroke.

Written by Catharine Paddock PhD

Courtesy: Medical News Today Note: Any medical information available in this news section is not intended as a substitute for informed medical advice and you should not take any action before consulting with a health care professional.