‘La nuit blanche’. No, it is not a delicious pastry. It’s the French expression for staying up all night and not going to bed until the next evening, which in most cases will leave you pretty irritable. But losing one night’s sleep may affect more than just your mood; a new study by Swedish researchers shows that it also influences the methylation of your genes.
Our metabolism is fine-tuned to ensure that it operates according to our energy needs, i.e., high during the day and low at night. Controlling this is our internal time-keeping mechanism, the circadian clock, in which environmental cues control the rhythmic expression of clock genes that in turn regulate metabolism and behavior.
People doing shift work or suffering from sleep deprivation may also experience metabolic alterations. However, the effect that sleep loss has at the molecular level in tissues involved in metabolism is still largely unknown in humans.
In their study, Cedernaes and colleagues looked at how one night of sleep deprivation influenced the methylation and expression of core circadian clock genes. They recruited 15 healthy male volunteers prepared to endure two biopsies from their thigh muscle and superficial stomach fat in the name of science: one after a full night’s sleep and another after a night without sleep.
- Using a methylation array to examine DNA methylation levels in the regulatory sequences of clock genes, they found that methylation at PER1 and CRY1 increased in adipose tissue after sleep deprivation.
- Sleep deprivation also decreased the abundance of BMAL1 and CRY1 mRNA in skeletal muscle and impaired glucose responses as assessed by an oral glucose tolerance test.
Lead author Cedernaes says, “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. It was interesting that the methylation of these genes was altered so quickly, and that it could occur for these metabolically important clock genes”.
For some bedtime reading, head over to the Journal of Clinical Endocrinology and Metabolism, July 2015.