Many studies have observed a link between disrupted sleep and weight gain, especially among shift workers and people with insomnia who are found to have a higher risk of obesity. New findings now suggest that there may indeed be a reaction in the body when we do not get enough sleep, leading to the storage of more fat and the loss of muscle mass. 

The study titled "Acute sleep loss results in tissue-specific alterations in genome-wide DNA methylation state and metabolic fuel utilization in humans" was published in the journal Science Advances on Aug. 22.

According to the Centers for Disease Control and Prevention (CDC), 35 percent of adults in the United States do not get enough nightly rest. It is recommended that people aged 18 to 60 years sleep for at least 7 hours each night.

The new findings show that sleep has an "irreplaceable function," according to first author Jonathan Cedernaes, a circadian researcher at Uppsala University in Sweden. "Sleep is not just to conserve energy, it has so many functions," he said.

Fifteen healthy men were recruited by the research team and asked to provide their fat and muscle samples on two different days — the first time after a night of good sleep, and the second time after they had stayed up all night.

When examining the fat tissue collected after the sleepless night, the research team found elevated levels of proteins as well as other changes which could promote higher storage of fat in the body. On the other hand, the muscle samples showed a decrease in structural protein which is essential for building muscle mass. 

"Sleep loss by itself is reducing proteins that are the key components of muscle," Cedernaes stated.

As studies have observed a trend of reduced muscle mass among shift workers, past researchers highlighted the role of other factors like our tendency to eat snacks when staying up late or the reduced levels of physical activity due to sleep loss-related fatigue. But the new findings indicate that tissue-specific mechanisms are at work regardless of these other factors.

Cedernaes explained that the loss of sleep could disturb the hormonal cycle of the body. This not only impairs the production of testosterone and growth hormones, but also triggers an increase in the morning levels of the stress hormone cortisol which increases fat storage. Additionally, the team observed an increase in inflammation after the night of sleeplessness, which has been significantly associated with the risk of type 2 diabetes. 

In further studies, the research team is looking into diet plans, exercise plans, and other methods to reduce these harmful effects. "It may be the case, for example, that eating protein-rich foods or doing resistance training might reduce the risk of muscle degradation," Cedernaes said.