People who don’t get enough sleep during the week may be able to reduce their risk for nonalcoholic fatty liver disease (NAFLD) by catching up on the weekends, researchers say.
“Our study revealed that people who get enough sleep have a lower risk of developing NAFLD than those who get insufficient sleep,” Sangheun Lee, MD, PhD, from Catholic Kwandong University, Incheon, South Korea, and colleagues wrote in Annals of Hepatology.
However, they cautioned that further research is needed to verify their finding.
Previous studies have associated insufficient sleep with obesity, hypertension, diabetes mellitus, and cardiovascular disease, as well as liver fibrosis.
A busy weekday schedule can make it harder to get enough sleep, and some people try to compensate by sleeping longer on weekends. Studies so far have produced mixed findings on this strategy, with some showing that more sleep on the weekend reduces the risk for obesity, hypertension, and metabolic syndrome, and others showing no effect on metabolic dysregulation or energy balance.
Accessing a nation’s sleep data
To explore the relationship between sleep patterns and NAFLD, Dr. Lee and colleagues analyzed data from Korea National Health and Nutrition Examination Surveys collected from 2008 to 2019. They excluded people aged less than 20 years, those with hepatitis B or C infections, liver cirrhosis or liver cancer, shift workers and others who “slept irregularly,” and those who consumed alcohol excessively, leaving a cohort of 101,138 participants.
The survey didn’t distinguish between sleep on weekdays and weekends until 2016, so the researchers divided their findings into two: 68,759 people surveyed from 2008 to 2015 (set 1) and 32,379 surveyed from 2016 to 2019 (set 2).
Set 1 was further divided into those who averaged more than 7 hours of sleep per day and those who slept less than that. Set 2 was divided into three groups: one that averaged less than 7 hours of sleep per day and did not catch up on weekends, one that averaged less than 7 hours of sleep per day and did catch up on weekends, and one that averaged more than 7 hours of sleep throughout the week.
The researchers used the hepatic steatosis index (HSI) to determine the presence of a fatty liver, calculated as 8 x (ratio of serum ALT to serum AST) + body mass index (+ 2 for female, + 2 in case of diabetes). An HSI of at least36 was considered an indicator of fatty liver.
Less sleep, more risk
Participants in set 1 slept for a mean of 6.8 hours, with 58.6% sleeping more than 7 hours a day. Those in set 2 slept a mean of 6.9 hours during weekdays, with 59.9% sleeping more than 7 hours. They also slept a mean of 7.7 hours on weekends.
In set 1, sleeping at least7 hours was associated with a 16% lower risk for NAFLD (odds ratio, 0.84; 95% confidence interval, 0.79-0.89).
In set 2, sleeping at least 7 hours on weekdays was associated with a 19% reduced risk for NAFLD (OR, 0.81; 95% CI, 0.74-0.89). Sleeping at least 7 hours on the weekend was associated with a 22% reduced risk for NAFLD (OR, 0.78; 95% CI, 0.70-0.87). Compared with those who slept less than 7 hours throughout the week, those who slept less than 7 hours on weekdays and more than 7 hours on weekends had a 20% lower rate of NAFLD (OR, 0.80; 95% CI, 0.70-0.92).
All these associations held true for both men and women.