Studies have found that people who routinely don’t get enough sleep are more likely to be overweight than people who get adequate sleep. Additionally, two recent cohort studies of middle-aged and older community-dwelling adults have found insufficient sleep to be associated with lower muscle mass. A new study published in Science Advances delved into the reasons why.
Researchers sampled blood, skeletal muscle, and fat tissue from fifteen healthy young white men after allowing them to sleep for up to eight and a half hours, and again after making them stay up all night. They found that sleep loss was associated with decreased metabolic activity in muscle tissue and increased activity in fat tissue, meaning there was less muscle building and more fat building going on in the sleep-deprived men. It has been suggested that acute sleep loss might cause hormonal disruptions, which then lead to metabolic changes in fat and muscle tissues. This study did find several hormonal changes in the sleep-deprived men, including increased levels of the hormone cortisol, which is involved in the breakdown of muscle tissue.
The researchers also observed changes to the DNA coating (methylation) in the sleep-deprived subjects similar to patterns seen in the fat cells of obese individuals and people with type 2 diabetes. This suggests that chronic disruption of sleep may actually change gene expression to favor creation of new fat tissue. So, according to the researchers, acute sleep loss may alter metabolism and actually change gene activation to favor both the breakdown of muscle and building of new fat tissue.
Not getting enough sleep is associated with obesity, metabolic syndrome, and type 2 diabetes. Getting the recommended seven to nine hours a night might be an important key to good health.