Extremes in Sleep Duration Linked to Increased Abdominal Fat in Minority Young Adults

Laurie Barclay, MD

March 08, 2010

March 8, 2010 — Extremes in sleep duration are related to increases in abdominal fat in minority young adults, according to the results of a longitudinal epidemiologic study reported in the March 1 issue of Sleep.

"Appropriate amounts of sleep are important for maintenance of healthy weight," lead author Kristen G. Hairston, MD, from Wake Forest University School of Medicine in Winston-Salem, North Carolina, said in a news release. "In a group of African-American and Hispanic participants, those who slept less than this had greater increases in belly fat over a five-year period."

The goal of this study was to determine the association of 5-year change in computed tomography (CT)–derived visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) with sleep duration in 2 minority groups from 3 US communities. The study cohort consisted of 332 African Americans and 775 Hispanic Americans, aged 18 to 81 years, who were enrolled in the Insulin Resistance Atherosclerosis Study (IRAS) Family study.

The main outcomes were abdominal CT scan findings and body mass index (BMI) assessed at a 5-year interval. Baseline questionnaire determined sleep duration, which was categorized as 5 hours or less, 6 to 7 hours, and 8 hours or more. The adjusted association between sleep duration and 5-year fat accumulation was evaluated with generalized estimating equations, after adjustment for age, race, sex, study site, baseline fat measure, physical activity, total calories, smoking status, and education.

Change in fat measures was predicted by the interaction of age with sleep duration (P < .01). Among participants younger than 40 years, sleep duration of 5 hours of sleep or less vs 6 to 7 hours was associated with greater accumulation of BMI (1.8 kg/m2; P < .001), SAT (42 cm2; P < .0001), and VAT (13 cm2; P > 001). Compared with sleep duration of 6 to 7 hours, 8 hours or more of sleep was also associated with a greater accumulation of BMI (0.8 kg/m2; P < .001), SAT (20 cm2; P < .01), and VAT (6 cm2; P < .05) in this age group. In participants older than 40 years, there was no significant association between sleep duration and change in fat deposition.

Participants reporting 5 hours of sleep or less consumed more total calories (2224 kcal) than those reporting 6 to 7 hours (1920 kcal) or 8 hours of sleep or more (2199 kcal).

"In this minority cohort, extremes of sleep duration are related to increases in BMI, SAT, and VAT in persons younger than 40 years old," the study authors write.

Limitations of this study include somewhat limited exposure assessment through self-report and lack of data on important confounders such as depressive symptoms.

"Short sleep has become more common in the U.S., and minorities are disproportionately affected," the study authors conclude. "As we continue to explore the reasons for the rapidly climbing obesity and diabetes rates among young people, particularly ethnic minority groups, our results linking extremes in sleep duration with increases in abdominal fat areas may explain a component of the increase."

The National Institutes of Health supported this study. One of the study authors has disclosed various financial relationships with Proctor and Gamble, Sanofi-Aventis, Eli Lilly, Merck, Pfizer, Novo-Nordisk, Amylin, Pfizer, and Dexcom Inc. The other study authors have disclosed no relevant financial relationships.

Sleep. 2010;33:289-295.

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