Sleep loss wrecks DNA
How just one bad night can damage the cells that help keep your body healthy
YOU might think that losing the odd night’s sleep is nothing more than tiresome.
But a new study has found that staying up all night – or suffering a disrupted night’s sleep – on just one occasion may have more serious implications for our health than was previously thought.
Researchers in Sweden discovered that missing a single night of sleep can alter the genes that control our cellular clocks.
This can affect everything from changes in our body temperature, appetite and even brain activity.
‘Previous research has shown that our metabolism is negatively affected by sleep loss,’ said Jonathan Cedernaes, lead author and a researcher at Uppsala University. With sleep loss having been linked to an increased risk of obesity and type 2 diabetes, he added that his team’s results indicate that ‘changes of our clock genes may be linked to such negative effects caused by sleep loss’.
In the study, published in the Journal of Clinical Endocrinology and Metabolism, 15 healthy men attended a laboratory on two separate occasions – either sleeping as normal for eight hours or being kept awake.
To minimise the influence of environmental factors, the researchers strictly controlled light conditions, food intake and activity levels, and the participants were restricted to bed both times. Afterwards, tissue samples were taken from fat on the stomach and muscle on the thigh – tissues that are important for regulating metabolism and controlling blood sugar levels.
A study of the samples showed that the regulation and activity of clock genes was changed after just one night of sleep loss.
The activity of genes is regulated by a mechanism that is called epigenetics. This involves chemical changes to the DNA molecule that 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 reveals how much of the genes’ product is made, was altered.
The results were different for the muscular and fat tissues. This suggests that not only do different tissue samples function on different clocks, but that sleep has a much larger role in switching genes on and off than scientists previously thought.
Dr Cedernaes said this could suggest that important molecular clocks are ‘no longer synchronised between these two tissues’ and added that such ‘ clock desyn- chrony’ between tissues has been linked to metabolic problems.
‘As far as we know, we are the first to directly show that epigenetic changes can occur after sleep loss in humans,’ said Dr Cedernaes, adding that the changes took place quickly and in ‘ metabolically important clock genes’.
He added that his team does not yet know how permanent these changes are.
‘It could be that these changes are reset after one or several nights of good sleep,’ he said. ‘On the other hand, epigenetic marks are suggested to be able to function a sort of metabolic memory, and have been found to be altered in, for example, shift workers and people suffering from type 2 diabetes.
‘This could mean that at least some types of sleep loss or extended wakefulness, as in shift work, could lead to changes in the genome of your tissues that can affect your metabolism for longer periods.’