Researchers at Uppsala University have demonstrated that one night of sleep loss has a tissue-specific impact on the regulation of gene expression and metabolism in humans.
This may explain how shift work and chronic sleep loss impairs our metabolism and adversely affects our body composition.
In the new study, the researchers studied 15 healthy normal-weight individuals who participated in two in-lab sessions in which activity and meal patterns were highly standardised. In randomised order, the participants slept a normal night of sleep (over eight hours) during one session and were instead kept awake the entire night during the other session.
The morning after each night-time intervention, small tissue samples (biopsies) were taken from the participants' subcutaneous fat and skeletal muscle. These two tissues often exhibit disrupted metabolism in conditions such as obesity and diabetes.
At the same time in the morning, blood samples were also taken to enable a comparison across tissue compartments of a number of metabolites. These metabolites comprise sugar molecules, as well as different fatty and amino acids.
The tissue samples were used for multiple molecular analyses, which first of all revealed that the sleep loss condition resulted in a tissue-specific change in DNA methylation, one form of mechanism that regulates gene expression.
DNA methylation is a so-called epigenetic modification that is involved in regulating how the genes of each cell in the body are turned on or off, and is impacted by both hereditary as well as environmental factors, such as physical exercise.
"Our research group was the first to demonstrate that acute sleep loss in and of itself results in epigenetic changes in the so-called clock genes that within each tissue regulate its circadian rhythm. Our new findings indicate that sleep loss causes tissue-specific changes to the degree of DNA methylation in genes spread throughout the human genome. Our parallel analysis of both muscle and adipose tissue further enabled us to reveal that DNA methylation is not regulated similarly in these tissues in response to acute sleep loss," said Jonathan Cedernaes who led the study.
"It is interesting that we saw changes in DNA methylation only in adipose tissue, and specifically for genes that have also been shown to be altered at the DNA methylation level in metabolic conditions such as obesity and type 2 diabetes. Epigenetic modifications are thought to be able to confer a sort of metabolic "memory" that can regulate how metabolic programmes operate over longer time periods. We, therefore, think that the changes we have observed in our new study can constitute another piece of the puzzle of how chronic disruption of sleep and circadian rhythms may impact the risk of developing for example obesity," noted Jonathan.
The findings have been published in the journal Science Advances....