Deirdre Budd’s Blog

According to a study from the Wisconsin Sleep Cohort, which was presented at SLEEP 2010: Associated Professional Sleep Societies 24th Annual Meeting, Chronic Insomnia is associated with an approximately 2-fold increased risk for all-cause mortality.

Researchers, led by Laurel Finn, MS, a biostatistician at the University of Wisconsin School of Medicine in Madison, determined all-cause mortality by examining a social security death index in June 2009. They used Cox proportional hazards regression to estimate mortality hazard ratios. These were adjusted for body mass index, age, sex, and chronic conditions that patients said their physicians had diagnosed, including emphysema, chronic bronchitis, angina, coronary heart disease, heart attack, stroke, hypertension, and diabetes.

The study looked at the association between chronic insomnia and mortality rate, independent of health conditions. Subjects were drawn from participants in the Wisconsin Sleep Cohort Study who completed 3 mailed surveys in 1989, 1994, and 2000. Surveys asked about insomnia-related topics such as difficulty falling asleep, difficulty getting back to sleep, repeated awakening, and early arousal. Respondents marked symptoms as frequent (≥5 times per month) or not frequent (<5 times per month). They were considered to have chronic insomnia if they reported symptoms on at least 2 surveys.

Ms. Finn, who presented the survey said, “Sleep duration has been linked to (increased) mortality, and a lot of insomniacs have short sleep duration. We wondered if this could be one of the mechanisms by which short sleep duration leads to mortality. We have been studying these people for 20 years, and have a lot of data on them.” The ongoing study has a population-based cohort, which allowed researchers to examine the natural history of participants. 

The study is preliminary, and the next step is to examine how insomnia affects health outcomes in comorbid conditions. “People with insomnia are fatigued. [Higher mortality could result] if they have a chronic condition and they don’t follow-up on treatment [because of the fatigue],” The findings of this study should prompt doctors to take insomnia more seriously and look for the root causes whether they be behavioural, or if there is real difficulty falling asleep or maintaining sleep. There are some new pharmacotherapies that work on specific kinds of insomnia. However, the root causes need to be addressed.

It can be difficult to determine whether the insomnia itself increases mortality or if the underlying conditions are causing the insomnia. This study has offered the clearest, most structured look at this topic so far.