Researchers have determined that the genes controlling the biological clocks in cells throughout the body are altered after losing a single night of sleep.

Molecular analyses of the collected tissue samples showed that the regulation and activity of clock genes was altered after one night of sleep loss. The activity of genes is regulated by a mechanism called epigenetics. This involves chemical alterations to the DNA molecule such as methyl groups – a process called methylation – which regulates how the genes are switched on or off. The researchers found that clock genes had increased numbers of such DNA marks after sleep loss. They also found that the expression of the genes, which is indicative of how much of the genes’ product is made, was altered.

“As far as we know, we are the first to directly show that epigenetic changes can occur after sleep loss in humans, but also in these important tissues”, says Dr. Jonathan Cedernaes. “It was interesting that the methylation of these genes could be altered so quickly, and that it could occur for these metabolically important clock genes”, he continues.

The changes that the researchers observed were however different in the adipose tissue and the skeletal muscle. “This could suggest that these important molecular clocks are no longer synchronized between these two tissues”, Dr. Cedernaes says. “As such, ‘clock desynchrony’ between tissues has been linked to metabolic pathologies, this could suggest that these tissue-specific changes were linked to the impaired glucose tolerance that our participants demonstrated after the night that they had been kept awake.”

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