Poor quality sleep linked to fatty liver disease
According to research published in the Journal of Clinical Endocrinology and Metabolism. Another study found that night owls may also be at higher risk for developing more severe fatty liver disease, researchers reported in the International Journal of Obesity.
From the accumulation of fat in the liver, non-alcoholic fatty liver disease (NAFLD) and its most severe form, nonalcoholic steatohepatitis (NASH), are responsible for an increasing proportion of advanced liver disease in the United States and around the world. In many cases, the accumulation of fat in the liver is associated with obesity and diabetes, which is why it is sometimes called metabolically-associated fatty liver disease, or MAFLD. Fatty liver can lead to liver fibrosis, cirrhosis and even liver cancer. In the absence of effective approved medical therapies, management depends on lifestyle changes, such as weight loss and exercise.
MAFLD and Sleep Disorders
Previous research has suggested that sleep disturbances are linked to metabolic conditions, so Yan Liu, PhD, of Sun Yat-sen University in China, and colleagues conducted a study to assess whether sleep behaviors affect risk to develop MAFLD.
The study included 5,011 participants between the ages of 30 and 79 who lived in southern China. They were diagnosed with MAFLD if imaging showed hepatic fat accumulation that occurred with overweight, obesity, diabetes, or other metabolic dysfunctions. About 28% were diagnosed with MAFLD.
Based on participants’ reported sleep behaviors, researchers calculated a healthy sleep score and assessed potential links between sleep and MAFLD risk. Going to bed before 11 p.m., sleeping seven to eight hours a night, taking shorter naps during the day, and having little snoring or insomnia were each worth one point. A higher score indicates better quality sleep. The score was adjusted for demographics, lifestyle, medication use, and comorbidities.
People with low sleep quality scores were most at risk for MAFLD, while those with good or moderate sleep quality were less likely to have the disease. Late bedtime, daytime naps longer than 30 minutes, and snoring were each strongly linked to increased risk. Of all sleep behaviors, snoring had the greatest impact: People who snored were 59% more likely to have MAFLD than those who didn’t, after adjusting for obesity and other factors. People with disturbed nighttime sleep who took long naps during the day had more than double the risk of NAFLD. With each point increase in the healthy sleep score, the risk of MAFLD fell by 16%.
Further analysis revealed that people with a sedentary lifestyle and abdominal obesity were more likely to be affected by poor quality sleep. But obesity was only responsible for 21% of the total impact of sleep quality on MAFLD risk.
“Sleep behaviors, both cumulatively and individually, are associated with the risk of MAFLD,” the study authors wrote. “Public health awareness and strategies should be encouraged to curb MAFLD.”
Chronotype and hepatic steatosis
In another study, Claudia Vetrani, PhD, and Giovanna Muscogiuri, MD, of Federico II University in Italy, and their colleagues sought to understand the potential link between fatty liver disease and chronotype in obese people. Chronotype refers to a person’s ability to carry out activities at a specific time of day, whether a “morning lark” or a “night owl”. Chronotype has previously been shown to play a role in metabolic disorders.
A total of 87 people with NAFLD and obesity were included in the study; 74% were women and the average age was 40 years old. Based on their chronotype score, 31% had a morning chronotype, 37% had an intermediate chronotype, and 32% had an evening chronotype. People with an intermediate chronotype were younger, on average, than those with morning or evening chronotypes.
People with an evening chronotype had significantly larger waist and hip circumferences as well as a higher body mass index (BMI) than those with a morning chronotype. They also had a higher BMI and waist circumference than people with an intermediate chronotype.
While all participants had NAFLD, only those with an evening chronotype exceeded the threshold for NASH, or severe fatty liver disease. Additionally, these individuals scored significantly higher on visceral adiposity, liver fat, steatosis, and NASH indices, even after adjusting for age, sex, and BMI.
“The evening chronotype is associated with more severe NAFLD independent of age, gender, and BMI than the morning chronotype and intermediate chronotype in obese people,” the researchers concluded.
“[T]The relationship between chronotype and obesity could be explained by hormonal, behavioral and lifestyle characteristics that have a profound impact on circadian rhythm and body weight management,” they suggested. They then plan to treat “misaligned” people using therapies that affect circadian rhythms.
Click here to read the summary of MAFLD and sleep in the Journal of Clinical Endocrinology and Metabolism.
Click here to read the summary of the chronotype study in the International Journal of Obesity.
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