Sleep duration versus sleep insufficiency as predictors of cardiometabolic health outcomes

Abstract

Objective: The objective of the present study was to investigate the relationship between sleep insufficiency and sleep duration, particularly regarding negative cardiometabolic health outcomes already considered to be affected by reduced sleep time.

Methods: A total of N=30,934 participants from the 2009 Behavioural Risk Factor Surveillance System (BRFSS) answered questions about their sleep duration as well as subjective feelings of sleep insufficiency. Outcomes included body mass index (BMI), obesity (BMI ≥ 30kgm(-2)) and history of hypertension, diabetes, hypercholesterolaemia, heart attack and stroke. Linear and logistic regression models examined whether cardiometabolic outcomes were associated with (1) sleep duration alone, (2) sleep insufficiency alone and (3) the combined effect of sleep duration and sleep insufficiency.

Results: Results indicated that, when examined alone, sleep duration <5h (versus 7h) was related to BMI (B=2.716, p<0.01), obesity (B=2.080, p<0.000001), diabetes (B=3.162, p<0.000001), hypertension (B=2.703, p<0.000001), hypercholesterolaemia (B=1.922, p<0.00001), heart attack (B=4.704, p<0.000001) and stroke (B=4.558, p<0.000001), and sleep insufficiency (days per week, continuous) was related to BMI (B=0.181, p<0.01), obesity (B=1.061, p<0.000001) and hypercholesterolaemia (B=1.025, p<0.01). All of these relationships remained significant after adjustment for covariates, except for diabetes and sleep duration. Also, after adjustment, a significant relationship between insufficient sleep and hypertension emerged (B=1.039, p<0.001). When evaluated together, after adjustment for covariates, significant relationships remained between sleep duration <5h (versus 7h) and BMI (B=1.266, p<0.05), obesity (B=1.389, p<0.05), hypertension (B=1.555, p<0.01), heart attack (B=2.513, p<0.01) and stroke (B=1.807, p<0.05). It should be noted that relationships between sleep duration >9h (versus 7h) were seen for heart attack (B=1.863, p<0.001) and stroke (B=1.816, p<0.01). In these models, sleep insufficiency was associated with hypercholesterolaemia (B=1.031, p<0.01) and hypertension (B=1.027, p<0.05).

Conclusions: These analyses show that both sleep duration and insufficiency are related to cardiometabolic health outcomes, and that when evaluated together, both variables demonstrate unique effects.

Figure 1

Odds Ratios of risk of cardiometabolic outcomes associated with sleep duration categories, relative to 7 hours of sleep, after adjustment for covariates. Values represent adjusted analyses of Model 3, which included sleep duration and adjusted for sleep insufficiency, age, sex, race/ethnicity, education, income, employment, marital status, census region, minutes of exercise, any exercise in past month, alcohol intake, heavy drinking, smoking status, healthy diet, household size, overall health, physical health, and mental health. BMI was included as a covariate for all outcomes except obesity. White asterisks indicate Odds Ratios significant at the p<0.05 level. Black asterisks indicate that Odds Ratios were significant in Model 1 (without adjusting for sleep insufficiency) but not in Model 3.