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Poor sleep associated with NAFLD development in middle-aged Koreans

People who slept for no more than 5 hours nightly or experienced poor-quality sleep were at increased risk for developing nonalcoholic fatty liver disease, according to a recent study.

Researchers evaluated the duration and quality of sleep in 45,293 middle-aged workers at a large company in South Korea, along with their spouses (mean age, 39.7 years), via the Pittsburgh Sleep Quality Index. Ultrasonography was performed in each case to determine the presence of nonalcoholic fatty liver disease (NAFLD). The cohort had a mean sleep duration of 6.4 ± 1.1 hours. Criteria for NAFLD were met in 10% of women and 43.1% of men.

Sleep duration of 5 hours or fewer per night was significantly associated with NAFLD in both men (OR=1.28; 95% CI, 1.13-1.44) and women (OR=1.71; 95% CI, 1.38-2.13) after controlling for confounders including alcohol and tobacco use, blood pressure, demographics, sleep apnea and physical activity level. Continuous analysis indicated reduced risk for both sexes for every additional hour of sleep (OR=0.92; 95% CI, 0.89-0.95 for men; OR=0.88; 95% CI, 0.83-0.93 for women). Additional adjustment for BMI eliminated statistical significance in men (OR=1.03; 95% CI, 0.9-1.19), but not in women (OR=1.59; 95% CI, 1.23-2.05).

Multivariate analysis indicated ORs of 1.10 (95% CI, 1.02-1.19) for men and 1.36 (95% CI, 1.17-1.59) for women with poor sleep quality compared with those with good sleep quality. Limiting analysis to the nonobese or those without metabolic syndrome or diabetes yielded no associations between sleep quality and NAFLD among men. Associations remained, however, among women (OR=1.32; 95% CI, 1.07-1.64 for nonobese, OR=1.49; 95% CI, 1.24-1.79 for no metabolic syndrome and OR=1.32; 95% CI, 1.13-1.55 for no diabetes).

“Our results indicate that short sleep duration and poor sleep quality are independently associated with an increased risk for NAFLD in middle-aged adults, and this association was modified by gender,” the researchers concluded. “Our observations may have significant public health implications for identifying potentially modifiable factors associated with NAFLD. Prospective studies are necessary to confirm the findings of our study.”