Not only does a poor night’s sleep disrupt our biological clock, it even changes the epigenetic structure of our DNA. In some cases, it appears that this change is irreversible.
Our biological clock is responsible for ensuring that our bodily functions follow a certain rhythm. The sleep-wake rhythm which is mainly influenced by melatonin and cortisol, is the best known example of that. The biological clock can be disrupted by, for example, working shifts, travelling from east to west and when the clocks change from winter or summer time.
Fifteen men participated in a two-night sleep experiment in a laboratory on two occasions. On the first two nights they were allowed to sleep through the night, but during the second session they were kept awake for one night. During the study, blood samples were taken to monitor the activity of certain ‘clock genes’, such as CLOCK and CRY1.
Disturbed sleep was found to increase the methylation of CRY1 and BMAL1. This resulted in fewer proteins being produced which help to regulate the circadian rhythm. Methylation involves methyl groups attaching themselves to the DNA, which means certain genetic information can no longer be translated into proteins.
“We have proven with just one single night of not sleeping through the night can change the epigenetic and transcription profile of important circadian clock genes”, said the researchers. "It is entirely possible that, after a couple of good night’s sleep, these changes will be reversed. But, on the other hand, epigenetic changes in people who often work in shifts are sometimes of a lasting nature."
Jonathan Cedernaes, Megan E. Osler, Sarah Voisin, Jan-Erik Broman, Heike Vogel, Suzanne L. Dickson, Juleen R. Zierath, Helgi B. Schiöth, and Christian Benedict, Acute Sleep Loss Induces Tissue-Specific Epigenetic and Transcriptional Alterations to Circadian Clock Genes in Men, JCEM Volume 100, Issue 9, 13 juli 2015.