Sleep: Clock Genes Altered When One Night Of Rest Missed

Statistics show that over 70 million Americans suffer from sleep disorders and wakefulness. Yet even for those of us who sleep relatively well, did you know that losing a single night of sleep can alter the genes that control the biological clocks in our cells?

A new study conducted by Swedish researchers at Uppsala University and the Karolinska Institute examined 15 healthy, normal-weight men who came to the study lab on two separate occasions for almost 2-night long stays. On the second night, the participants slept a typical 8-hour night (within the recommended sleep-range for adults) during one of the two sessions while they were kept awake in the other of the sessions, in random order. To minimize the influence of various environmental factors as well, researchers kept participants bed-restricted while awake and strictly controlled their food intake.

Tissue samples were then taken following the second night on both occasions from the superficial fat on the stomach and from the muscle on the thigh--both tissues that are important for regulating metabolism, as well as controlling blood sugar levels. Blood samples were also taken before and after participants consumed a sugar solution to test insulin activity.

Molecular analyses of the collected tissue samples showed that just one night of sleep loss altered the regulation and activity of clock genes. 

"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," said Jonathan Cedernaes, lead author on the study and a researcher at Uppsala University, in a news release. "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."

However, researchers noted how the changes were different in the tissue samples. "This could suggest that these important molecular clocks are no longer synchronized between these two tissues," Cedernaes concluded. "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."

Only further research will tell how persistent the cellular changes are.

More information regarding the findings can be seen via the Journal of Clinical Endocrinology and Metabolism. 

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