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Low sleep efficiency, shorter sleep duration associated with greater cold susceptibility, findings suggest

Monday, January 26 2009 | Comments

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What's This? Among healthy adults, shorter sleep duration and lower sleep efficiency are both associated with an increased risk of developing a cold following exposure to a rhinovirus, according to findings from a prospective study.

Researchers recruited 153 adults aged 21 to 55 years to participate in the study. For 14 consecutive days, the participants reported the previous night's sleep duration and sleep efficiency, as well as how rested they felt following sleep. Subsequently, they received nasal drops containing a rhinovirus and were monitored for 5 days under quarantine conditions.

Overall, as sleep duration and sleep efficiency decreased, the likelihood of developing a cold increased.

In an analysis that adjusted for age and viral-specific antibody titers, the odds of developing a cold were nearly 3 times greater among those who reported <7 hours of sleep per night relative to those who reported >=8 hours (odds ratio [OR], 2.94; 95% CI, 1.18-7.30). The corresponding odds ratio for individuals reporting 7 to 8 hours of sleep was 1.63 (95% CI, 0.63-4.19).

Similarly, the odds of developing a cold were 5.5 times greater among those with a sleep efficiency of <92% relative to those with a sleep efficiency of >98% (OR, 5.50; 95% CI, 2.08-14.48). The corresponding odds ratio for individuals with a sleep efficiency ranging from 92% to 98% was 3.94 (95% CI, 1.50-10.37). When the researchers dichotomized sleep efficiency according to the traditional threshold of 85%, the odds ratio for developing a cold with a sleep efficiency of <=85% was 5.37 (95% CI, 1.51-19.1).

Of the 2 sleep variables, sleep efficiency was a stronger overall correlate of illness, the researchers noted.

These associations remained significant in analyses that additionally adjusted for body mass index, race, income, education, sex, season of exposure, psychological variables previously linked with cold risk, smoking, alcohol consumption, and exercise.

Feeling rested following sleep was not associated with cold risk. (Cohen S, et al. Arch Intern Med 2009;169:62-67.)

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