A new study out of Norway suggests a possible link between insomnia and mortality, but findings are mixed and well-controlled studies are lacking, according to an analysis in BMC Public Health. The aim of the study titled “Midlife insomnia and subsequent mortality: the Hordaland health study” was to examine the effect of insomnia in middle age on all-cause mortality.
Using a cohort design with 13-15 years follow-up, mortality registry data were linked to health information obtained during 1997-99, as part of the community-based Hordaland Health Study (HUSK), in Western Norway. More than participants aged 40–45 provided baseline information on self- reported insomnia using the Karolinska Sleep Questionnaire Scale.
BMC Public Health reports that “Insomnia was reported by 5.6% (349/6236) at baseline and a significant predictor of all-cause-mortality (hazard ratio [HR] = 2.74 [95% CI:1.75-4.30]). Adjusting for all confounders did not attenuate the effect (HR = 3.34 [95% CI:1.67-6.69]). Stratifying by gender, the effect was especially strong in men (HR = 4.72 [95% CI:2.48-9.03]); but also significant in women (adjusted HR = 1.96 [95% CI:1.04-3.67]). The mortality risk among participants with both insomnia and short sleep duration (<6.5 hours) was particularly high, whereas insomnia in combination with normal/greater sleep duration was not associated with mortality.”
Researchers concluded that insomnia was associated with “a three-fold risk of mortality over 13-15 years follow-up. The risk appeared even higher in males or when insomnia was combined with short sleep duration, although such unadjusted subgroup analyses should be interpreted with caution.”
