Poor quality sleep linked to higher risk of early death, studies find

POOR quality sleep – whether from insomnia, sleep fragmentation or nightmares – is associated with increased risk of death, experts have said.

One study, conducted at Penn State College of Medicine in Hershey, Pennsylvania, and presented at the annual meeting of the Associated Professional Sleep Societies in Seattle, suggests insomnia may be as hazardous as obstructive sleep apnoea.

“Insomnia with objective short sleep duration is associated with an activation of the stress system, ie, higher secretion of cortisol and increased risk of high blood pressure,” said lead author Dr Alexandros Vgontzas. He and his associates examined the effects of insomnia that persisted for at least a year.

The subjects included 1,741 randomly selected men and women. During 14 years of follow-ups among men, the mortality rate was 19.6%. Among women, who were followed for 10 years, the mortality was 10.3%.

Compared with men who had normal sleep patterns and sleep durations of at least six hours, men with insomnia and a shorter duration of sleep had mortality risks that were up to five times greater. While mortality risk was also increased among women with similar characteristics, the association was not statistically significant.

“The longer follow-up of men may explain why we did not have the same finding in women,” said Dr Vgontzas. “Another possibility is that men are more vulnerable physically to this type of insomnia.”

Because “insomnia with objective sleep duration – of less than six hours – has significant medical consequences, this type of insomnia should become a medical priority in terms of its detection and treatment,” he said. "

Another study assessed sleep duration using actigraphy, a small instrument worn on the wrist that evaluates sleep-wake cycles. The investigators found sleeping fewer than five hours per night increased the risk of death among elderly women, but not among elderly men.

Dr KL Stone at California Pacific Medical Centre in San Francisco and co-investigators monitored 3,052 women (average age of 83.6 years) and 3,055 men (average age 76.4 years) for at least three 24-hour periods.

Compared with women who slept at least eight hours nightly, women who slept fewer than five hours had a significantly higher risk of death. Men who got fewer than five hours of sleep per night also had an increased mortality risk, but this was not statistically significant, which, again may be related to study conditions.